REST/Booster Engine Pre-heat with DPDT Switch Modification

TROLL

2007 Winnebago View 23H
Meant to have the word “if” in my first sentence, didn’t mean to sound so bossy!

To an Espar noob after reading so much frickin info about it, but some of it wrong and/or outdated, it may even be better to put your first version aside (or remove it, or gray it out) since the real meat of the current and “best” solution is your second revision. That’s what I was thinking even if I didn’t state it clearly. Sometimes you gotta read a 10 page thread to get the complete story, but sometimes it’s nice to have it all in the first post.

Again, my thanks for your help with this info. I’m getting ready to reinstall the removed and neglected hydronic heater for the sole purpose of being able to preheat my engine in cold temps to reduce engine wear.
 

Aqua Puttana

Poly - Thread Finder
...it may even be better to put your first version aside (or remove it, or gray it out) since the real meat of the current and “best” solution is your second revision.
...
I tend to not like removing information which shows the thoughts and development. Editing can be a pain. I can't imagine doing what some of the YouTube vlog'ers do to get out a short video.


I can't say under my present lifestyle that I don't have time to change/edit. It comes down to motivation and inclination.

I'll give it some thought.

:cheers: vic
 

koenb

Active member
And if anyone knows an OEM DPDT switch part number that is recommended and fits in the oval blank space behind/to the right of the steering wheel (not on the actual center console) I’d love to get something ordered. Assume we won’t luck out with a “heating” symbol on it but if we could that would cure my OCD. Or maybe it’s possible to remove an unrelated symbol and leave it blank?
Not sure if this got answered, but the you can get a DPDT fog light switch and steal a top cover from another like the rear window heater and have a symbol that kindoff resembles and engine block heating. Just swap the covers. MB PN 006-545-51-47. I've only found them available on ebay from europe or from MB dealers. Unavailable from dodge.

Added:
Thanks Vic. Posts 92, 103, 105. The dual fog light switch has no output pins for the contact terminal for the alternate positions like a standard 6 pin dpdt switch has. See the picture attached. Those pins are necessary in wiring the bypass circuit correctly. After reviewing the pinouts for the ventilator switch dodge PN 5120-490AA, MB PN 901-545-04-07. The switch body has the required pins (pins 5 and 6) to provide the correct circuit function. Swapping the covers can still be done, I attached a picture of the small tabs limit a switch from rocking 2 ways. As I have discovered, the SPST and DPDT switches use the same internal rocker mechanism, but what makes the switches either momentary or single/double action has to do with these tabs and a small spring and ball bearing inside that "locks" it into the position.
vic
 
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TROLL

2007 Winnebago View 23H
Not sure if this got answered, but the you can get a DPDT fog light switch and steal a top cover from another like the rear window heater and have a symbol that kindoff resembles and engine block heating. Just swap the covers. MB PN 006-545-51-47. I've only found them available on ebay from europe or from MB dealers. Unavailable from dodge.
Awesome, thank you. A quick google and Ebay search came up empty on that part number -- its correct? And if you can swap covers, are there any easier to source DPDT switches that could have the cover swapped over? Perhaps not if you're seeking out this one specifically. Thank you for your help, appreciate it!
 

koenb

Active member
Awesome, thank you. A quick google and Ebay search came up empty on that part number -- its correct? And if you can swap covers, are there any easier to source DPDT switches that could have the cover swapped over? Perhaps not if you're seeking out this one specifically. Thank you for your help, appreciate it!
The dual fog light switch is the only factory DPDT non-momentary switch i'm aware of. There are other DPDT and DP3T switches that are either momentary or do not have normally open contacts (on-on-on vs on-off-on). I found it on ebay by searching keywords like "sprinter switch fog" and Vito instead of sprinter. I also like to filter the results down to used items to cut out the keyword tagged universal items that always turn up in search. Also found it available at my local MB dealership. I ended up buying a used rear window defog switch just to use the cover on my dual fog light switch for the engine preheat.

Added:
Thanks Vic. Posts 92, 103, 105. The dual fog light switch has no output pins for the contact terminal for the alternate positions like a standard 6 pin dpdt switch has. See the picture attached. Those pins are necessary in wiring the bypass circuit correctly. After reviewing the pinouts for the ventilator switch dodge PN 5120-490AA, MB PN 901-545-04-07. The switch body has the required pins (pins 5 and 6) to provide the correct circuit function. Swapping the covers can still be done, I attached a picture of the small tabs limit a switch from rocking 2 ways. As I have discovered, the SPST and DPDT switches use the same internal rocker mechanism, but what makes the switches either momentary or single/double action has to do with these tabs and a small spring and ball bearing inside that "locks" it into the position.
vic
 
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koenb

Active member
I need to amend the previous posts, the dual fog light switch will not work without internal modification due to lack of center switch post terminals(pins 5&6). The ventilator switch PN 901-545-04-07 is the switch to use.
Note: Swapping covers may require a slight removal of a couple specific tabs inside the cover.
 
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Aqua Puttana

Poly - Thread Finder
I need to amend the previous posts, the dual fog light switch will not work without internal modification due to lack of center switch post terminals(pins 5&6). The ventilator switch PN 901-545-04-07 is the switch to use.
Note: Swapping covers may require a slight removal of a couple specific tabs inside the cover.
If you give the number of the post(s) with maybe a bit of detail, I can move this information to the proper place(s) and strike out where needed. Thanks for the follow up.
vic
 

koenb

Active member
If you give the number of the post(s) with maybe a bit of detail, I can move this information to the proper place(s) and strike out where needed. Thanks for the follow up.
vic
Thanks Vic. Posts 92, 103, 105. The dual fog light switch has no output pins for the contact terminal for the alternate positions like a standard 6 pin dpdt switch has. See the picture attached. Those pins are necessary in wiring the bypass circuit correctly. After reviewing the pinouts for the ventilator switch dodge PN 5120-490AA, MB PN 901-545-04-07. The switch body has the required pins (pins 5 and 6) to provide the correct circuit function. Swapping the covers can still be done, I attached a picture of the small tabs limit a switch from rocking 2 ways. As I have discovered, the SPST and DPDT switches use the same internal rocker mechanism, but what makes the switches either momentary or single/double action has to do with these tabs and a small spring and ball bearing inside that "locks" it into the position.
 

Attachments

Aqua Puttana

Poly - Thread Finder
Thanks Vic. Posts 92, 103, 105. The dual fog light switch has no output pins for the contact terminal for the alternate positions like a standard 6 pin dpdt switch has. See the picture attached. Those pins are necessary in wiring the bypass circuit correctly. After reviewing the pinouts for the ventilator switch dodge PN 5120-490AA, MB PN 901-545-04-07. The switch body has the required pins (pins 5 and 6) to provide the correct circuit function. Swapping the covers can still be done, I attached a picture of the small tabs limit a switch from rocking 2 ways. As I have discovered, the SPST and DPDT switches use the same internal rocker mechanism, but what makes the switches either momentary or single/double action has to do with these tabs and a small spring and ball bearing inside that "locks" it into the position.
Great! I'll follow up with some edits.
vic

I lost focus. I have since copied and pasted your comments to posts 92, 103, 105.
 
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Nabsim

New member
My Sprinter 316 (UK) already has a switch to turn on the coolant heater. The switch is not enabled until the ignition is turned on so not a pre heater more quick warm up.
A previous owner fitted a calorifier to provide domestic hot water using engine coolant. I would like to feed the MB DPDT switch from my habitation battery bank and have it so it runs when I operate the switch regardless of ignition position.
Can anyone help with what I need to do please, I keep looking at these threads but still unsure.
When I pulled the switch out only two wires are connected, I put 12v on the incoming side but it did not operate when I flicked the switch. Only two wires connected, this was installed OEM as far as I am aware.
In the pic the switch seen still in the dash was added to turn on the separate Eberspacher DT4 Airtronic while driving and is additional to the habitation controls/thermostat and can be ignored. I do not know if the OEM switch wiring was changed when this was fitted.

DB3BC928-EF1D-4A48-A180-64BEE09418AA.jpeg
 

Cheyenne

UK 2004 T1N 313CDi
My Sprinter 316 (UK) already has a switch to turn on the coolant heater. The switch is not enabled until the ignition is turned on so not a pre heater more quick warm up.
A previous owner fitted a calorifier to provide domestic hot water using engine coolant. I would like to feed the MB DPDT switch from my habitation battery bank and have it so it runs when I operate the switch regardless of ignition position.
Can anyone help with what I need to do please, I keep looking at these threads but still unsure.
When I pulled the switch out only two wires are connected, I put 12v on the incoming side but it did not operate when I flicked the switch. Only two wires connected, this was installed OEM as far as I am aware.
In the pic the switch seen still in the dash was added to turn on the separate Eberspacher DT4 Airtronic while driving and is additional to the habitation controls/thermostat and can be ignored. I do not know if the OEM switch wiring was changed when this was fitted.

View attachment 143968
Hi and welcome from a fellow Brit,

Looking at your dash you have a T1N (pre 2007 in UK) and for those the Eberspacher switch was the central 'Bow tie' section of the left most heater control switch (unless you had the 7 day timer fitted but I've never seen one in the UK). The switch you have shown must have been a later change made by a PO so no idea how it has been wired.

And the factory fit Eberspacher water heater should only run with the engine actually running so possibly wiring changes have already been made if ti works with just the ignition on.

Keith.
 

Nabsim

New member
Hi Keith, it has REST and all the other functions working on the multi switch further to the left. My Sprinter is actually a motorhome registered in 2007 but the chassis cab is mid 2005 from what I can find out so spot on.
I was told I could cause problems leaving the ignition switched on so haven’t done it except for very short periods while testing. The Hydronic unit is mounted under passenger headlight and everything looks as if it was from new. I know a previous owner had a heat exchanger, calorifier and the Eberspacher DT4 airtronic fitted as I have the invoices but it doesn’t mention anything about the Hydronic.
I have Lifepo4 batteries and 300W solar so in summer it would be ideal if I could run the hot water from the Hydronic when stood for days.
The calorifier has an immersion element (230v) that has never been wired up so I also have that option but it means getting a decent inverter.
 

Aqua Puttana

Poly - Thread Finder
Hi and welcome from a fellow Brit,

Looking at your dash you have a T1N (pre 2007 in UK) and for those the Eberspacher switch was the central 'Bow tie' section of the left most heater control switch (unless you had the 7 day timer fitted but I've never seen one in the UK). The switch you have shown must have been a later change made by a PO so no idea how it has been wired.
...
There was a discussion in the T1N section that revealed that there are some rare T1N's which have an OEM dash rocker switch for Espar aka Eberspacher heater control. I'm not saying that the switch in the picture is OEM for the heater. I'm just pointing out that it *could* be.

Chopped wires do indicate that someone has been messing with it.

vic
 
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koenb

Active member
My Sprinter 316 (UK) already has a switch to turn on the coolant heater. The switch is not enabled until the ignition is turned on so not a pre heater more quick warm up.
A previous owner fitted a calorifier to provide domestic hot water using engine coolant. I would like to feed the MB DPDT switch from my habitation battery bank and have it so it runs when I operate the switch regardless of ignition position.
Can anyone help with what I need to do please, I keep looking at these threads but still unsure.
When I pulled the switch out only two wires are connected, I put 12v on the incoming side but it did not operate when I flicked the switch. Only two wires connected, this was installed OEM as far as I am aware.
In the pic the switch seen still in the dash was added to turn on the separate Eberspacher DT4 Airtronic while driving and is additional to the habitation controls/thermostat and can be ignored. I do not know if the OEM switch wiring was changed when this was fitted.

View attachment 143968
This does not look like an OEM switch installation. The switch may be OEM, but I suspect the wiring and install is not. The two disconnected wires would feed into the switches illumination circuit (pins 1 and 10). The two connected wires at pins 3 & 7 (red and brown/white) would be the in/out to the single pole switch contacts. I doubt MB would have left the illumination wiring disconnected, so likely someone snipped out an old switch from another van and didn't run the extra two wires for the illumination.

What is the part number on the side of the switch body? Should be in yellow lettering and you might have to disconnect the wiring connector to read it and also post a picture of the pins on the back and symbol on the cover. It would help identify it.
 
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Not directlyrelated to the present thread, but recently, and for the first time in a decade of ownership, I noticed my rotary dash board heater/cooling switchlight illuminated when moved to another outflow choice from where I always keep it. Curiouser and curiouser, so said Alice in Wonderland.

If the rotary switch small LED light is not showing, what does that mean? The operation of the switch appears to not be compromised, but what do I know? Thanks to all here.
 

Nabsim

New member
This does not look like an OEM switch installation. The switch may be OEM, but I suspect the wiring and install is not. The two disconnected wires would feed into the switches illumination circuit (pins 1 and 10). The two connected wires at pins 3 & 7 (red and brown/white) would be the in/out to the single pole switch contacts. I doubt MB would have left the illumination wiring disconnected, so likely someone snipped out an old switch from another van and didn't run the extra two wires for the illumination.

What is the part number on the side of the switch body? Should be in yellow lettering and you might have to disconnect the wiring connector to read it and also post a picture of the pins on the back and symbol on the cover. It would help identify it.
Would the van still have the Rest Combination switch installed and the Heat exchanger for rear of the van installed if not OEM? I would think when they fitted the calorifier and DT4 in the rear they would have broken into the original wiring as the combination switch operates the heat exchanger they fitted.
Do the two snipped wires only operate the led and nothing else? I was going to connect it up again but have gotten used to using it just by feel of the position. Where they mount isn’t in direct line of sight when driving and that’s the only time you can use it currently.

Does anyone know if it is correct not to operate with just ignition turned on? It would take about 40 minutes or so for it to heat the 22litre hot water tank so it’s not just a short time.

@Cheyenne I think what you call the bowtie switch is what I am calling a combination switch. If so yes I have that

edit: sorry I am posting in this thread, thought it may have been a quick answer. I will make a new thread of my own so I don’t mess this one up any more 👍
 
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Aqua Puttana

Poly - Thread Finder
Some general information for the Espar aka Eberspacher heaters is here.
Clicking on the link will take you to the correct post.)


vic

Added:
FWIW.
Some discussion about the Dash Rocker Switch heater control for 2 hour time out.


There is other discussion before and after that post. Real information starts at Post #39.
 
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autostaretx

Erratic Member
The REST switch only turns on a coolant circulation pump and the cabin fan at speed 1.
It can be totally independent of the Espar functions.
(i don't know if it's a separate coolant pump, or if it shares duty with the Espar-related pump)

--dick
 

Bill B.

Member
REST/Booster Engine Pre-heat with DPDT Switch Modification

*******************
Edit:

In case there is anyone who reads further down and begins to question whether this circuit will work...

The DPDT Switch circuit I designed and provide in this post will work as advertised. Any discussion further on in the thread is related to overall circuit details and trying to understand all the MB OEM control logic. The DPDT switch circuit combined with REST is a simple solution that works as intended.

Added:
A basic outline for the physical installation has been added. Post #47.

********************

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.

Edit: If it doesn't cure the ABS pre-start check fault/glitch the response is fairly simple. Just turn off the DPDT Switch and REST before starting. Should you forget and get the dash warning lights, then shutting off the engine for re-start will clear the faults. Just leave the key off for 15 seconds for the ECM relay to power down. If you don't wait long enough for the ECM relay power down the ECM will remember the faults and display them again upon re-starting.

Most of the connections are found in the dash area on the ATC Module. I know that running a 2 conductor cable from the DPDT dash switch to the BK/BL/DG wire Espar Pin #6 at the Booster will work. 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 method 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.

View attachment 128327


This is the original diagram without the notes.

View attachment 64539


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.

vic

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

*******************************************

Some Information Related to the Circulation Pump

Recently I have unraveled more information regarding the Coolant Circulation Electric Pump.

After looking at the documentation related to the MB Sprinter Aux. Electric Coolant Pump it appeared to me that either the description in the Service Manual or the schematics are wrong. So far the schematics are the most accurate, but maybe not 100%.

The schematics show the Coolant Pump to be basically fed by 12 volt sources which are subject only to the key position There aren't any fancy logic controls shown in the schematics. Maybe those fancier controls are on other MB models? :idunno:

Based upon the thoughts mentioned above, I installed an indicator light to monitor the 12v power to my Electric Circulation Pump. It was fairly easy because my DIY Booster run with diode modification gave me an easy tap point in the fuse holder. My conclusion is that my pump has 12v power subject to the key. In the case of my 2004 with OEM Booster Heater, the circulation pump runs as long as the key is turned on or the engine is started/running.

I've tried many different operating conditions. So far the circulation pump runs 100% the time.



This is what I found with my Booster Heater aka Except Program Timer unmodified OEM controls/Circulation Pump testing.



My test light shows that the pump runs 100% of the time.


Nope. The pump runs 100% of the time.


Nope. The pump runs 100% of the time.


Nope. The pump runs 100% of the time.


Nope. The pump runs 100% of the time.


Unable to test above 230F, but the pump runs 100% of the time..

From my testing so far it appears that the pump running all the time as shown by the Service Manual schematics is the most accurate.

View attachment 64543

View attachment 64418

As an additional check I removed my DIY Diode Run fuse to test if the Espar Booster would run while the engine was off. I powered the Pin #7 with the DIY SPDT dash switch. The Espar did not respond at all. I set the ATC REST control to enable (DG/RD powered from ATC Pin C1-2 - Circ Pump Running) with the DIY SPDT dash switch still on. The Espar didn't respond at all.

I replaced the DIY Diode Run fuse. The Espar heater fired up.

Basic Conclusions:

The Coolant Circulation Pump runs subject to the key position as shown in the 8W-42- 09 schematic. There is not a circulation pump complex logic control with my Booster Heater option.

The Circulation Pump is not automatically powered up with the Espar Pin #7 enabled. (Espar wouldn't fire with only Pin #7 energized/enabled)

The Circulation Pump is powered by the ATC C1-2 pin DG/RD wire to run during the REST operation. (Splice #362 isn't in the path.)

The wire DG/RD being powered does not backfeed 12v to Espar Pin #6. There must be a blocking diode for the Booster Heater as shown in schematic 8W-42-09. The correct control wiring/logic is likely what I show in blue.

For the Espar Booster Heater aka Except Program Timer to operate 12v power must be supplied to Espar Pin #6 (enable). For the Espar Booster Heater that 12v is supplied to Espar Pin #6 via Splice #362. Splice #362 also supplies the Circulation Pump. If power to Espar Pin #6 is interrupted the Booster Heater will power off. That is regardless of whether the engine is running or not. That is another fact which supports that the Circulation Pump must be energized 100% of the time for the Booster Heater to operate.

As an aside, Splice #S362 is listed as "Near Circulation Pump Diode" Fig. 18. Under Driver Seat.

View attachment 64419

I haven't located the diode on my 2004 yet.

Please note that the circulation pump information above is derived from testing performed on one OM647 Booster Heater equipped Sprinter and doesn't necessarily apply to the Dash Inset Control aka Program Timer units or possibly even other model/optioned Sprinters.

vic

Added:
What turned in to a rather long and meandering thread with additional Espar information for my 2004 is here. (Anyone can feel free to condense and re-post any important stuff there to another thread.)

Some 2004 Espar Heater Notes
https://sprinter-source.com/forums/showthread.php?t=30384

There are other Espar threads in the T1N Database section.
Aqua,
Great engineering and super write up!
 

Aqua Puttana

Poly - Thread Finder
I was requested by PM for wire colors to the switch.

This what I came up with.

EsparRunDPDTswitch.jpg

vic
 

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