Wiring Heater Booster to run from Switch

davisdave · Dec 21, 2013

Besides the blue wire in the dash, you still need to "uninhibit" :lol:

the heater booster by providing 12v to the black/blue/green dot wire at the heater booster.

One way is to cut black/blue/green dot wire at the heater booster plug and join the side going to the heater booster to the blue wire. This way, the blue wire in the dash will turn both wires on. I dont know if this is bad when you return control to the atc. Both wires are minimal current signal wires.

Does the REST button work on a timer or sense the coolant temp? Thought i read that? Anyhoo, the green/red wire in the dash runs the coolant pump.

220629 · Dec 21, 2013

davisdave said:
Besides the blue wire in the dash, you still need to "uninhibit" the heater booster by providing 12v to the black/blue/green dot wire at the heater booster.

One way is to cut black/blue/green dot wire at the heater booster plug and join the side going to the heater booster to the blue wire. This way, the blue wire in the dash will turn both wires on. I dont know if this is bad when you return control to the atc. Both wires are minimal current signal wires.

Does the REST button work on a timer or sense the coolant temp? Thought i read that? Anyhoo, the green/red wire in the dash runs the coolant pump.

~~Nope.~~ 2014/01/01 Edit: YEP!! ~~For the Booster Heater nothing more than the 12 volt power to Pin #7 blue is necessary.~~ MB ordered custom control. So Pin #6 is not an "Output" as labeled in 8W-42-11. It is an "Input". For the Booster Heater it is used to verify that power is going to the Aux Electric Coolant Pump. For the "Timed Units" it is a 2nd enable. I suggest using a SPDT switch to prevent feedback of the 12 volts to the ATC.

My modification only applies to the Booster Heater or in other words the "Except Program Timer" unit.

Look more closely at the schematics. I did after my power to Pin #7 didn't get my Booster Heater running. :bash:

The black/blue/~~orange~~ not OG it is DG = Dark Green wire is connected to Pin #6 which is the Booster Heater 12 volt "Fused Optional Equipment Relay Output" to power from the pump, ~~not the other way around~~. By design, the Sprinter Espar pump Pin #6 is always a 12 volt ~~output~~ "Input" not "Output" as it is clearly labelled in8W-42-11. MB uses it in a different way for the "Timed" controllers.

Once the Espar is enabled by powering pin #7, the Espar Booster Heater unit will provide Pin #6 12 volt output to the Aux Electric Coolant Pump just as it does during any programmed orderly shutdown/cooldown cycle. The Espar unit runs completely on its own ~~to do that~~ for an orderly cooldown/shutdown and doesn't care whther the electric coolant pump is running or not. The standard Espar heater needs no control signals ~~related to~~ the Sprinter special operations do.

It is very important to be certain to stay with the proper heater style when checking/following the circuits. Boy, have I learned that. All the Sprinter basic Espar Hydronic Heater units are the same with custom controls, but the control design which MB applies for the Booster and the Aux is completely different. It is easy for the schematics to trip a person up. (At least it was for me. :bash:

again.

)

davisdave said:
...
Does the REST button work on a timer or sense the coolant temp? ...

~~I don't know. I thought I read somewhere that it was timed. I do know that the REST fan operation has a finite interval, but I've not explored how it works because it hasn't been important to me.~~

It is timed. From my 2004 manual.

Residual Engine Heat Utilization (REST)

The REST switch (1) is located on the
center section of the dashboard.
The residual engine heat utilization
system can be used to keep the
vehicle interior warm for some time
after the engine is switched off.
Turn the key to position 0 in the ignition lock or
remove it altogether.

To switch on:

1. Press the residual engine heat utilization switch (1),
the indicator lamp (2) lights up.
The blower will run at speed 1 regardless of the
setting of the airflow control.
2. Set the temperature control as required, refer to
"Heating, Ventilation".

To switch off:

Press the residual engine heat utilization switch (1)
again, the indicator lamp (2) goes out.
The residual engine heat utilization is automatically
switched off if:
1. If the key is turned to position 2 in the ignition lock,
2. after about 30 minutes,
3. if the battery voltage is too low.

Anybody know if 30 minutes of modified Booster Operation or Aux. Heater is enough to defrost the windshield and provide noticeable cabin warmth?

20141203 edit: Now that I went through last season I can say for certain that 30 minutes is enough warm up time even below 0F.

vic

davisdave · Dec 22, 2013

Now, now, Vic...are you saying that Roger, myself, and countless others have done extra work :shifty:

You do see that there are 4 relays in the mod description...one of which applies 12v to the black/blue/green dot wire at the heater.
Easy enough to test. Only cut the blue wire, apply 12v, and see if it works. Someone who has done the mod with relays could disconnect the wire going to the black/blue/green dot wire and see if it fires.
Cautionary note: there are at least two blue wires in the bundle in the dash, one is not the correct one. Mine was toward the top of the bundle and a bit larger. You can see in the pic the other blue wire i cut which has been repaired. Also note blue wire, and green/red wire which i left open on the right side (atc side)...

The van side of my heater booster plug has the following wires:
big red
big brown
green
blue/red stripe
black/blue/green dot
blue

There is a good pic of this in the very first post by Roger.

FWIW: With the 7 day timer and the D2, there was a similar signal deal...two 12v pins on the timer to turn on. One pin was 12v constant for clock and operation. A second pin needed 12v to run the heater which you could wire in different ways:
1. you could wire to accessory (key must be on)
2. you could wire to constant 12v (most campers would want this for continuous anytime running)
3. you could wire to D+ so engine had to be on

Happy Holidays All!

220629 · Dec 22, 2013

I thought that I have been pretty clear about what I am saying. 2014/01/01 Edit: While I was completely wrong using the incorrect Pin #6 "Output" label in 8W-42-11. It should be labelled "Input". The MB Sprinter Espar heater is not standard, MB ordered custom controls. I should have figured on that. :shifty:

The switch ~~with diode~~ install which I outline now DPDT Switch below will allow the "Except Program Timer" style Booster Heater to operate as an engine pre-heater. By using the REST function with the added DPDT switch then you will get approximately 30 minutes of fan operation on low speed to move the air past the Espar heated coolant/heater core without the engine running. I have tested and verified the circuit operation ~~even though my Booster Heater still is not starting~~.

davisdave said:
Now, now, Vic...are you saying that Roger, myself, and countless others have done extra work You do see that there are 4 relays in the mod description... Happy Holidays All!

If what I posted immediately above is what you need, then "yes" you did extra work and spent extra money. (That is still true.)If you want the Booster heater to run as a full blown Aux Cabin Heater with fan speeds and longer time then *maybe* you need all the components outlined and discussed earlier in this thread. I have no interest in doing that so I don't know if the methods/circuits outlined here are overkill or not.

Up to a short time ago I had no reason to worry about my Booster Heater. It didn't work and I was fine with that. Then a member mentioned about how he just made his work with a switch so that piqued my interest. As I said, I've reviewed this thread and nobody even posted any real schematics. Most all the discussion was about wire connections and relays kinda in a vacuum. When I reviewed the schematics the control logic and design slowly unfolded.

I believe that there is a difference in the two blue wires. One is solid blue, the other has a tracer. I don't have pictures.

As to needing relays...

They aren't needed for my mod. Just enabling the Espar heater with REST at the same time will do what I say above. I don't make the news, I only report the news. vic

Aqua Puttana said:
REST/Booster Engine Pre-heat with DPDT Switch Modification

My original circuit using a switch and a diode for REST engine pre-heat works, but it has some flaws in that it can backfeed 12 vdc into some other circuits connected to Splice #362. For a basic optioned Sprinter like mine that is not a problem. For Sprinters which have things tagged on to the Optional Equipment Relay it can have some negative effect. (Not necessarily serious, just a nuisance.)

Realizing that, I looked for another option. After a couple different solutions I developed a circuit that uses a common Double Pole Double Throw DPDT switch. This new circuit prevents any 12 vdc backfeeds and should also address the ABS module pre-start check glitch.

Most of the connections are found in the dash area on the ATC Module. It will be necessary to run a 2 conductor cable from the DPDT dash switch to the BK/BL/DG wire Espar Pin #6 at the Booster. That BK/BL/DG wire may be available in the area of the dash to cut and connect. Using the documentation that I have available to me I was not able to determine if that is a practical solution or not.

With the DPDT switch in "Normal" position (as shown) the REST and Booster Heater function per OEM design. With the DPDT switch in "Pre-heat" position REST powers up the DG/RD wire Circulation Pump which also enables the Espar heater. This allows approximately 30 minutes of pre-heat operation until REST times out.

Here is the basic circuit shown on the Booster Heater Diagram.

Presently my switch and diode arrangement does what I need for my engine pre-heating. I don't plan to change over to the new design. That said, the newer DPDT switch circuit modification is the better choice.

If anyone has questions please start another thread. That will allow me to move information to here rather than having this thread go too far off topic. vic

P.S. - Some PM's with Mortarsprayer got me back to thinking about this modification.

autostaretx · Dec 22, 2013

vic said:
Anybody know if 30 minutes of modified Booster Operation or Aux. Heater is enough to defrost the windshield and provide noticeable cabin warmth?

"noticeable"? ... yes.
"defrost the windshield"? ... probably. We've only "tested" it down to about 25F.
Near freezing, 15 minutes of operation was enough to warm the windshield enough to easily sweep off a quarter-inch-thick exterior accumulation of frost/ice.
(i'd go out in the morning and punch the "ignite" button, then come back in for the last cup of coffee.)

How hot the engine coolant is going to get in 15 or 30 minutes depends upon the exterior temperature, cabin fan speed and direction of howling winds through the radiator.
Above 25F it will certainly get up to 180F in less than 30 minutes.

The T1N Espar is a 5KW heater at full tilt, 2400 watt at "idle".

--dick

220629 · Dec 22, 2013

Dick,
Thanks for the input (as always). It sounds like the Booster running with the REST enabled should do what I need. vic

220629 · Dec 30, 2013

I will not be testing my theory of feeding the Espar heater with the blue wire switch. The heater has bested me. It doesn't look like it has ever run enough to even build up any soot on the combustion chamber. I doubt that it has ever been running since new. It is a feature most people aren't familar with so nobody probably ever even missed it.

I will say that my heater is a very reliable smoke machine. It is not a reliable heater.

Sorry that I won't be trying the blue wire feed. I've lived without the heater for 6 years. I'm not spending any more time or money on it.

vic

Andyandyandy · Dec 30, 2013

Sorry to hear you gave up on it Vic. I've been following this and the other thread thinking you might be the one to finally come up with a simple, or at least easier-to-follow solution. Thanks for trying and posting some useful observations. Were you testing the heater in the van, installing and removing it again and again? That idea doesn't sound too appealing. Your notes about the fuel feed being a slow trickle give me hope that maybe I can rig up a bench test with a sort of IV drip for fuel. Right now the Espar is sitting on the floor waiting for me to get around to taking it apart and cleaning it before trying to get it working. It seems like it would be a great option to have, but like you say, for two winters now I've gotten by just fine without it. Sometime I'll have a go at getting it running, but it's not the biggest priority. Anyways, thanks for the insights and have a good new year.

Andy

220629 · Dec 31, 2013

Andyandyandy said:
Sorry to hear you gave up on it Vic. ... Anyways, thanks for the insights and have a good new year.

Andy

Thanks.

Continued over in this thread to keep this one more on topic.

https://sprinter-source.com/forums/showthread.php?t=30427

vic

BlackHawk · Dec 31, 2013

I have my booster set up with the 4 relays per the diagram. Mine has my trademark, super improved, "remote heat" feature. :rad:

I added an additional 5 pin "always connected" relay, a cheap ON/OFF fob from Amazon, and a small trailer clearance light mounted under the rear bumper. What this enables my setup to do is this: The always connected side of the relay is hooked to the Fob box and the small rear light, the switching side of the relay is hooked up to the dash toggle switch. My van sits about 100' feet from the house, and I was finding my remote fob sometimes took two or three tries due to the distance. The little clearance light lets me know the heater is on. I used the additional relay in the setup so that power is NOT sent to the light when I use the dash switch.

My observations in extreme Minnesota cold with the van; I have 5 good glow plugs and the brand new style Benz relay controller. The van will always start. Down to 10F I start normally, using just the glow plugs, below 10F I start the heater booster with my remote Fob and left the heater run for at least 15 minutes. What I found is that any less time than 15 minutes results in lukewarm coolant tricking the coolant sensor into thinking the glow plug relay doesn't need be used... resulting in the van starting very hard. So, my morning ritual is to let it heat the coolant for 15 minutes before I jump in the van. If I do this, it pops off like its 50 degrees outside. This morning it was -18F, I let the heater run for about 20 minutes, and upon startup, my scan gauge was reading coolant in the low 90F range and my cabin was noticeably warmer.

220629 · Jan 1, 2014

OK. My style is to just throw information around and try to keep people informed here as best I can. Maybe that method comes from some of my R&D experience. I've learned that often even a wrong idea can get the thinking processes moving.

In my Sprinter Espar discussions I have been applying standard Espar D5 control schemes. As I should have suspected, MB never does things standard, so the Sprinter Espar heater has a custom control design that is different from other Espar heaters.

As DavisDave suggested a few times the Pin #6 on the SPRINTER Espar heater needs a 12V Input. It is not an Output as it is labeled in 8W-42-11. So he was correct and I apologize for any inappropriate replies.

I have gone back and corrected the posts which I could find.

Anyway, there is a fairly simple way to make the Booster Heater run with a switch while the engine is off.

Aqua Puttana said:
~~I haven't done this (yet).~~ I have done the switch/diode modification and I verified that it works.

The following is what I would do to enable the Booster Heater to operate as a stand alone heater, run the aux electric coolant pump, and warm the engine 2014/01/01 Edit: and cabin for 30 minutes without the engine running.

Locate the blue wire on the ATC Automatic Temperature Control module in the dash.

Chop the blue wire and insert the switch as shown below. The common terminal goes out to the ESPAR heater.

Locate the 12V constant power to the the dash power outlet.

Feed the SPDT switch with the 12V power.

All the above can be done right at the dash panel.

This is the latest circuit with a diode input. I have verified that it works.

Parts Required
1 ea. SPDT switch

1 ea. - 3 amp polarity blocking diode. - Radio Shack or equiv. (Model: 1N5404 Catalog # 276-1144 or 276-1143 for a few bucks)

1 ea. fuse holder (optional as circuit is protected by OEM fuse, but a bit high)

1 ea. 3 or 5 amp fuse. (optional)

4 ea. Quick taps (3 ea. under hood. I ea. for 12V + to the SPDT switch.)
http://www.amazon.com/Solderless-Wi...41PF5QY/ref=pd_sbs_auto_1/175-1240195-0825646

4 ea. or so butt connectors for diode and fuse holder.

Misc. shrink tubing or vinyl electrical tape

Approx 6 ft 18 or 20 ga wire (light green? - recycle from trailer wiring)

Install the SPDT switch per the blue wire directions.

The fuse/diode install is a bit more involved, but should easily be done in under an hour.

Remove front grill and headlight pod to access Espar heater wires.

Assemble fuse and diode wire assembly rather than piecing it together as you go. I doubled the diode axial leads back onto the fuse feed wires with a cable tie to provide support. The solid leads need to be stabilized or they can break out of the diode.

Use approx 2 ft. of wire to fuse. Connect diode to fuse with current flow toward the Espar wire. (You want to block backfeed to the pump during normal Espar operations.) I used about 4 ft of wire off the diode. Routing will affect the wire needed.

Unplug the Aux Electric Coolant Pump connector.
Locate the DG/RD conductor. Install fuse wire tap in that wire.

Route fuse assembly wire up over the brake booster. Route diode wire down to Espar connector area.

Unplug Espar connector. Carefully slice harness cover up an inch or so to access BK/BL/DG wire.
Install diode wire tap to BK/BL/DG.

Go back and secure new wires, fuse, etc. with cable ties.

Basic Circuit Description

The SPDT switch opens the blue wire from the ATC Automatic Temperature Control to stop any feedback of 12V to the ATC or other circuits. The constant 12V(+) (eg. - from the Power Outlet) feeds through the SPDT switch via the OEM blue wire to power Pin #7 "Heater On" or enable on the Espar heater. Note: The Espar will not actually start until it gets the "Pump Power Verify" signal to Pin #6 from the REST operation.

When the REST button is pushed the Aux Electric Coolant Pump is energized for a time of approx 30 minutes. The wire tapped off the DG/RD wire at the pump connector feeds 12V "Pump Power Verify" or 2nd Enable via the diode to Pin #6 of the Espar Heater. When the REST fan times out the "Pump Power Verify" 12V goes away and the Espar heater initiates a shutdown. When Pin #6 of the Espar is energized during any normal OEM Sprinter operation then the diode blocks any voltage from backfeeding to the Coolant Pump. (A diode in this configuration acts like a check valve in a water system.)

This circuit will not adversly affect any other OEM Sprinter circuit operations. The REST System will not turn on the Espar heater until the SPDT switch is "On" to enable Pin #7.

Using the SPDT switch assures no backfeed of power to the ATC or any other circuits. I wasn't able to determine for certain whether backfeeding of voltage to the ATC would have any adverse affects or not. The safe route is to use the SPDT switch.

It *may* be OK to just use a SPST switch and feed the Blue Pin #7 wire 12 volts directly without worrying about feedback. I don't recommend doing that though. 12v directly is fine.

There was a report of backfeed issues wit the ABS system checks upon starting. This circuit should address that. Just add one 87 relay near the Espar connector.

Aqua Puttana said:

REST/Booster Engine Pre-heat with DPDT Switch Modification

My original circuit using a switch and a diode for REST engine pre-heat works, but it has some flaws in that it can backfeed 12 vdc into some other circuits connected to Splice #362. For a basic optioned Sprinter like mine that is not a problem. For Sprinters which have things tagged on to the Optional Equipment Relay it can have some negative effect. (Not necessarily serious, just a nuisance.)

Realizing that, I looked for another option. After a couple different solutions I developed a circuit that uses a common Double Pole Double Throw DPDT switch. This new circuit prevents any 12 vdc backfeeds and should also address the ABS module pre-start check glitch.

Most of the connections are found in the dash area on the ATC Module. It will be necessary to run a 2 conductor cable from the DPDT dash switch to the BK/BL/DG wire Espar Pin #6 at the Booster. That BK/BL/DG wire may be available in the area of the dash to cut and connect. Using the documentation that I have available to me I was not able to determine if that is a practical solution or not.

With the DPDT switch in "Normal" position (as shown) the REST and Booster Heater function per OEM design. With the DPDT switch in "Pre-heat" position REST powers up the DG/RD wire Circulation Pump which also enables the Espar heater. This allows approximately 30 minutes of pre-heat operation until REST times out.

Here is the basic circuit shown on the Booster Heater Diagram.

Presently my switch and diode arrangement does what I need for my engine pre-heating. I don't plan to change over to the new design. That said, the newer DPDT switch circuit modification is the better choice.

If anyone has questions please start another thread. That will allow me to move information to here rather than having this thread go too far off topic. vic

P.S. - Some PM's with Mortarsprayer got me back to thinking about this modification.

Click to expand...

I just went out and tested the REST idea. Once the switch/diode is installed as described above you can run the fan on low for an approx 30 minute timed interval by merely pressing the REST button. So, start the heater with the SPDT switch/diode (SPDT on, push the REST button). That will warm the cabin and defrost the windshield for approx 30 minutes.

NOTE!!!
If the manual SPDT switch is turned on with the REST engaged the ESPAR heater will run ~~forever~~ for approx 30 minutes cycling on and off as to the temperature of the coolant. It will not be subject to the low fuel tank level shutoff or any other Sprinter added safety features.

To just warm the engine and cabin all that is needed is a switch and a diode. No relays, no tapping in under the driver seat, just a SPDT switch on the dash, a diode under the hood and a bit of wire. About 10 - 15 bucks in parts.

vic

I have wired and tested the switch/diode circuit to verify that it works.

vic

FFR5445 · Jan 25, 2014

I wired it per these latest instructions, and it does work. I didn't use a SPDT switch because I already had the SPST rear heater switch that fits in with the others. So I wired it up a SPDT relay to do essentially the same thing. Now all I do is press the REST button then press the heater button on the dash and in a few minutes, the ESPAR is running strong and there is warm air coming out the dash. I like the fact that wiring is much simpler and after 30 minutes it will shut off automatically (I haven't tested the 30 min shut off yet but I believe it would shut off). I do have one problem with this though. Every time I start the van with the REST button activated I get the ABS, ESP, and slipping tire warning lights on, and I can't shift out of park. If I shut off the van and restart it, the lights are gone and everything is back to normal. This is somehow related to the REST button being on. If I use the REST button and/or pre-heater button and remember to shut off the REST before starting, it works normally without any warning lights. So, can you guys help me figure out what is going on? It must be getting some feedback from it somehow. I installed diode 1N5404 like you suggest. I suppose I just need to remember to shut off the REST before starting it but I'd rather get it right and not have to worry about it.

220629 · Jan 25, 2014

FFR5445 said:
... I do have one problem with this though. Every time I start the van with the REST button activated I get the ABS, ESP, and slipping tire warning lights on, and I can't shift out of park. If I shut off the van and restart it, the lights are gone and everything is back to normal. This is somehow related to the REST button being on. ...

Ah.

A glitch. In trying to keep things simple maybe I got too cute. :idunno:

It very well may be related to the diode feeding power into the Espar control module Pin #6 from the Aux. Electric Coolant Pump feed when the heater is not running.

I have no idea what is included in the Mercedes special/custom internal Espar control electronics. I haven't been able to find any details in any searches.

Pin #5 is the Data Scan and is common to Splice #221. Splice #221 is common to the Instrument Cluster IC and Automatic Temperature Control ATC. So there may be some crosstalk to the IC via Pin #6 whenever the Electric Pump is powered and the heater is not enabled (power to Pin #7).

The easy solution is a relay that will provide 100% isolation when the Electric Pump is running and the heater enable power is not on.

Just replace the diode only with the added relay N.O. contact and connect the coil as shown. The diode is still necessary to keep any Espar voltage from backfeeding/operating the Aux. Electric Coolant Pump under "normal" Booster Heater mode.

I recommend switching the added "Engine Off Operation" SPDT to "Off" before starting the engine. That will de-energize the 87 relay, open the contacts, and prevent backfeed. (With your SPST switch that may be even more important to also prevent backfeed to the ATC.)

The Blue wire can be tapped for the 87 relay coil right at the Espar heater connector. The relay can be located near the Espar heater to keep the wiring shorter.

Aqua Puttana said:
REST/Booster Engine Pre-heat with DPDT Switch Modification

My original circuit using a switch and a diode for REST engine pre-heat works, but it has some flaws in that it can backfeed 12 vdc into some other circuits connected to Splice #362. For a basic optioned Sprinter like mine that is not a problem. For Sprinters which have things tagged on to the Optional Equipment Relay it can have some negative effect. (Not necessarily serious, just a nuisance.)

Realizing that, I looked for another option. After a couple different solutions I developed a circuit that uses a common Double Pole Double Throw DPDT switch. This new circuit prevents any 12 vdc backfeeds and should also address the ABS module pre-start check glitch.

Most of the connections are found in the dash area on the ATC Module. It will be necessary to run a 2 conductor cable from the DPDT dash switch to the BK/BL/DG wire Espar Pin #6 at the Booster. That BK/BL/DG wire may be available in the area of the dash to cut and connect. Using the documentation that I have available to me I was not able to determine if that is a practical solution or not.

With the DPDT switch in "Normal" position (as shown) the REST and Booster Heater function per OEM design. With the DPDT switch in "Pre-heat" position REST powers up the DG/RD wire Circulation Pump which also enables the Espar heater. This allows approximately 30 minutes of pre-heat operation until REST times out.

Here is the basic circuit shown on the Booster Heater Diagram.

Presently my switch and diode arrangement does what I need for my engine pre-heating. I don't plan to change over to the new design. That said, the newer DPDT switch circuit modification is the better choice.

If anyone has questions please start another thread. That will allow me to move information to here rather than having this thread go too far off topic. vic

P.S. - Some PM's with Mortarsprayer got me back to thinking about this modification.

Sorry for any problems.

vic

Edit: Another possibility.
You said a SPST switch? It could also be related to you not using a SPDT switch to avoid backfeeding into the ATC on the blue wire. The power backing into the ATC may trigger something in the splice #221. I don't have enough info about that to know for certain either. It would be interesting for you to install a SPDT switch as I indicated to see if the problem goes away.

teamtexas · Jan 25, 2014

I guess I'm kinda where you were at a few months ago Vic. My 2003 has the espar for heating while the engine is running. As far as I can tell it has never worked (since I've owned it). I too, thought I would never need to use it and have put it on the back burner for a few years. But I found myself in Ohio at the 1st of December and wishing I had done something with it. I've spent a few hours reading through your posts on the simple modification for the controls and the not so simple repairs to the espar. I guess I need to get out turn some wrenches to see what shape mine is in. Thanks for posting all your hard work.
Dan

MillionMileSprinter · Jan 25, 2014

teamtexas said:
I guess I need to get out turn some wrenches to see what shape mine is in. Thanks for posting all your hard work.
Dan

I pulled mine out, opened it up, cleaned it and put it back together. VIOLA! It worked! No new parts or any cost.
Go for it! :thumbup:

*actually it works intermittently, but before it wouldn't work at all. So it's better than before.

FFR5445 · Jan 25, 2014

Let me clarify a few things.
I am using switch 5103853AA. Yes, this is a SPST, but I wired it through a SPDT relay so that it functions exactly like the SPDT switch in your diagram. Please look over my schematic below. I list the colors for MY relay and those may not be universal.

The error happens when I start the vehicle and the ESPAR is running (REST on and switch on). The same thing happens when the ESPAR is not running but I am using the REST feature (REST on, switch off). Since it only happens when the REST is on regardless of the new heater switch is on or off, I believe it is related to the REST circuit. When I start the van, it performs its series of checks and is confused by something so it illuminates the error lights.

Vic,
I'm having trouble understanding your schematic of the new relay. Which are the 85/86 terminals and which are the 30/87 terminals?

Do you have this same issue?

220629 · Jan 25, 2014

FFR5445 said:
Let me clarify a few things.
...
Vic,
I'm having trouble understanding your schematic of the new relay. Which are the 85/86 terminals and which are the 30/87 terminals?

Do you have this same issue?

Your relay prevents backfeed. :thumbup:

I turn REST and the added switch off before starting. I'll try your way.

Here's the relay pins. Gotta run.

Aqua Puttana said:
REST/Booster Engine Pre-heat with DPDT Switch Modification

My original circuit using a switch and a diode for REST engine pre-heat works, but it has some flaws in that it can backfeed 12 vdc into some other circuits connected to Splice #362. For a basic optioned Sprinter like mine that is not a problem. For Sprinters which have things tagged on to the Optional Equipment Relay it can have some negative effect. (Not necessarily serious, just a nuisance.)

Realizing that, I looked for another option. After a couple different solutions I developed a circuit that uses a common Double Pole Double Throw DPDT switch. This new circuit prevents any 12 vdc backfeeds and should also address the ABS module pre-start check glitch.

Most of the connections are found in the dash area on the ATC Module. It will be necessary to run a 2 conductor cable from the DPDT dash switch to the BK/BL/DG wire Espar Pin #6 at the Booster. That BK/BL/DG wire may be available in the area of the dash to cut and connect. Using the documentation that I have available to me I was not able to determine if that is a practical solution or not.

With the DPDT switch in "Normal" position (as shown) the REST and Booster Heater function per OEM design. With the DPDT switch in "Pre-heat" position REST powers up the DG/RD wire Circulation Pump which also enables the Espar heater. This allows approximately 30 minutes of pre-heat operation until REST times out.

Here is the basic circuit shown on the Booster Heater Diagram.

Presently my switch and diode arrangement does what I need for my engine pre-heating. I don't plan to change over to the new design. That said, the newer DPDT switch circuit modification is the better choice.

If anyone has questions please start another thread. That will allow me to move information to here rather than having this thread go too far off topic. vic

P.S. - Some PM's with Mortarsprayer got me back to thinking about this modification.

vic

Edit a bit later in the afternoon:

First. Your 87a relay and SPST switch as shown prevents backfeed to the ATC. I agree that is not the problem.

FFR5445 said:
Let me clarify a few things.
...
The error happens when I start the vehicle and the ESPAR is running (REST on and switch on). The same thing happens when the ESPAR is not running but I am using the REST feature (REST on, switch off). Since it only happens when the REST is on regardless of the new heater switch is on or off, I believe it is related to the REST circuit. When I start the van, it performs its series of checks and is confused by something so it illuminates the error lights.
...
Do you have this same issue?

I messed with the REST and starting. I did find the lights stayed on the dash as you indicate.

What I found.
The ABS with other lights stay on if REST is on when the key is turned to first position. If the key is continued to the "start" position then the engine starts, the ABS, etc. lights stay on, and the shifter won't move (no unlock).

When the ABS, etc. lights were noticed to stay on then just cycling the key off for a bit and back on gets them to go off. After system check, on my 2004 if more than the ESP, Seatbelt, Traction (Spinning Wheel) and Battery lights stay on then the shifter remains locked after starting. If more than those 4 lights stay on, then cycling the key off for a bit, and then back on casued my ABS light to stay off and allow a normal start with no shifter lock issue.

Anyway, I agree that there is probably some Espar related interference during the IC lamp/system check. The pump power feeding to the Espar Pin #6 (Pump Run Enable) via the diode when Pin #7 (Heater Enable) is not powered likely puts a signal out on Pin #5 (Espar Data Link) to the Splice #221. That in turn feeds back into the IC Instrument Cluster and the ATC Automatic Temperature Control Data Link circuits during system checks. That spurious signal must interfere to cause the ABS related IC systems check to show failure.

My added 87 relay is probably not foolproof, but if the added Espar Run SPDT switch is switched to "Off" before any start attempt, then the ABS, etc. light/shift lock problem should not be an issue. I'm going to add the 87 relay to my Espar circuit for further checks. The added 87 relay will also add constant drain whenever the SPDT switch is switched on. Not a big deal as long as not left on.

I have tried operating the REST and Booster Heater once the engine is running with the diode in circuit. There were no dash light problems once started.

This just shows (again) how complex these beasts can be.

Even with an additional relay the "Engine Off Run" modification is still fairly simple and requires pretty basic wiring in the dash area and under the hood. Use it as you feel comfortable.

Thanks for the input. :thumbup:

vic

saddledoggy · Jan 26, 2014

When I looked at the title of the thread I thought, great! just what I'm looking for :smirk:

...Then I read the whole thread. :frown:

...This has to be the single most confusing thread in the history of this forum...(yes I am easily bewildered :idunno:

) Can't we just nuke it and rename a new thread... Wiring Heater Booster to run from Switch IS HARDER THAN YOU THINK! :laughing:

220629 · Jan 26, 2014

I agree, but how to recover??

The original design concept that opened this thread is more complex, but appears to more closely mimic the OEM operation.

Some other suggestions by others, including mine, are less complex and don't include features of the first more complex design.

saddledoggy said:
... Wiring Heater Booster to run from Switch IS HARDER THAN YOU THINK!

Not really. I think that designing a circuit for the Heater Booster to run from Switch IS HARDER THAN YOU THINK.

:cheers:

vic

surlyoldbill · Jan 27, 2014

The easy modification may add another layer of security to prevent van from being stolen. Who's going to figure out that they need to turn the REST switch off in order to allow the van to start?!
I saw a TV show once where they had convicted car thieves try to "steal" cars with different security devices. The "Club" only stopped them for 10 seconds, as they cut through the steering wheel and removed it. Various alarm systems were bypassed or deactivated in less than a minute, as were battery cut-offs. Locking steering column was broken pretty easy. The one thing that stumped them was a hidden kill switch, probably wired in-line to the starter or ignition/distributor, they worked on the car for 15 minutes and could not start it.

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