REST/Booster Engine Pre-heat with DPDT Switch Modification

Aqua Puttana

Poly - Thread Finder
The white smoke (fuel evaporating) comments are consistent to what I reported too.

...
As an aside.
As I have said before, I don't think that my Espar has ever worked since new. When the heater wouldn't fire I would get raw fuel out the exhaust just before shutdown. When I first got my heater firing reliably I didn't have the exhaust pipe connected. The heater would give a small amount of white smoke and then begin roaring a bit. There was no smoke once the main burner fired.

After operating a few times I connected the exhaust and set the REST timeout in motion. After a bit of warm-up the exhaust began billowing white smoke to the point that I was afraid that the neighbors might call the fire department. Fortunately it was quite windy so the smoke didn't linger much. I knew that the heater was firing smokeless without the muffler. The smoke was from all the fuel that was soaked into the muffler sound packing material. I saw no flame at the muffler so it was being evaporated off. The heater is now operating cleanly with no smoke. The exhaust system is fully connected.

I have been using the heater daily to assure it is OK. It is actually kinda nice to have it operating.

vic

...
 

ECU

Well-known member
I fired up the espar again today. No smoke. Yea!
 

TomLetsinger

2006 158" DIY toy hauler
Thank you Vic for the wiring diagram in the original post of this thread. Today I did the switch mod to make the Booster run with Rest - So Cool! This is exactly what I've wanted the boost heater to do - pre-heat the engine and cab for 10 minutes before I head out. It's a long downhill from our house so the van doesn't warm up at all for the first 20 minutes of driving. Now it does! Thank you!
Tom
 

TomLetsinger

2006 158" DIY toy hauler
So after a couple months of using the "Rest Preheat" function, I have one issue. Perhaps Vic or one of you other smarties has a suggestion.
I am often ready to go before the Rest function has timed out. I'd like for the Espar to continue to help heating the coolant for the long downhill from my house. What's the best way to keep it going? Is there a way to switch from Rest Preheat to normal heat booster operation without the Espar having to go through its shut down and restart cycles?
 

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Aqua Puttana

Poly - Thread Finder
... What's the best way to keep it going?
Best? Probably ordering the OEM heater with timer control.

...Is there a way to switch from Rest Preheat to normal heat booster operation without the Espar having to go through its shut down and restart cycles?
If the two enable inputs are kept live then the heater should cruise through the short time period of the electric coolant pump being off during engine starting.

That said, the Espar monitors the system voltage for the 12 volts to remain in range. During an engine start cycle the voltage may pull down enough to cause the Espar controls to notice which could initiate a heater shutdown anyway.

Be careful with messing with an enable signal that is not related to the electric aux coolant pump running. Without coolant circulation the Espar will overheat. There is a local high temperature shutdown, but my experience shows that the plastic covers and other parts can be melted/distorted if that emergency shutdown mode is employed too many times.

Another watch out is that should the Booster Heater switch modification trigger the ABS fault, etc., then a quick key off and on will not necessarily clear it. The ECM has a power down cycle (8 seconds comes to mind.) Without a complete power down cycle then any faults can remain in memory when the key is too quickly turned back on. In that situation the ABS faults will not self reset until a complete power down cycle is allowed.

Have fun. vic
 
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seans

Member
Vic, I've been away and missed this the first time around. This is a great mod. Leveraging the 30 minute timeout is brilliant because it keeps the battery from being drained too far. Thanks!
 

Aqua Puttana

Poly - Thread Finder
A DPDT Wiring Outline


I had a PM request for more How-to detail on my Espar DPDT Switch Modification. To be honest the circuit diagrams and description were never intended to be a step-by-step instruction. I thought that some basic knowledge should be applied. The following is an outline using my notes and poor memory. Use it at your own risk.

Wire taps are not loved by some people. For the not so critical heater taps I used wire taps. I always smear a bit of Vaseline on any connector, including wire taps, before installation. Some taps include silicone grease from the factory.

This harness will work to provide the wire and 2 each tap connectors.
https://www.amazon.com/Trailer-Wiri...&qid=1493603386&sr=8-49&keywords=trailer+wire

2 ea. butt splice connectors (can also be used with Vaseline).
https://www.amazon.com/VAPKER-Conne...8-2&keywords=butt+splice+connector+waterproof

Decide on where you want your DPDT switch to be located and mounted in the cabin/dash area.

Connect wires to the switch and run 4 wires from the switch out through the firewall to the engine compartment. (I found that the chunk of trailer wiring harness works well.) There are spare openings near the steering column area main harness through the firewall. Be certain to seal the opening. It is amazing how much cold air can enter the cabin through a rather small opening.

Electrical color tape is handy to duplicate the OEM wire colors.
https://www.amazon.com/3M-Scotch-El...sr=8-2&keywords=multi+colored+electrical+tape

Another possible marking method is to use sticky labels folded over the wires.

Down at the Espar Heater connector strip off a section of harness wrap black tape.

Locate the BK/BL/DG aka Black/Blue/Dark Green wire. Cut that wire in a place that allows a butt connector to be installed on each side of the separated wire. Butt splice the two individual wires to your DPDT wire harness as shown on the diagram.

Locate the BL aka Blue wire on the Espar connector. Use a tap connector to connect the DPDT harness wire as shown in the diagram.

Locate the Aux Electric Coolant Pump on the firewall. (Follow the heater hose off the EGR to the pump.)

Locate the DG/RD aka Dark Green/Red wire that feeds the Aux pump. Use a tap connector to connect the DPDT harness wire as shown in the diagram.


10.3.3 BoosterPreHeatRESTrev2e.jpg


That's it. No additional fuses are needed because the OEM fuses will protect what is needed.
Note: Cost can be minimized by just using wire and connectors rather than buying the items I suggested. The parts I suggested are mostly for illustration.

Good luck.

vic

EsparRunDPDTswitch.jpg
 
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abaccus

New member
I just finished doing this modification and I want to say thanks to Vic and everyone else that got this mod sorted out! Ski season will be much less stressful with an always-warm engine!

I did do a slight tweak to the install, though, because I wanted to use the OEM rear heat (SPST) switch similar to the original 4-relay mod (for no reason other than vanity). I did this by using 2 SPDT relays to emulate the function of the DPDT switch. This actually cleaned up my wiring runs a bit because I only had to send a single wire through the firewall. I mounted the relays under the battery tray so that they are very close to the espar should I ever need to check on anything. Now I just need to clean the burner out so it starts more reliably!
 

marbled_rye

New member
Hi All- Thanks for sharing all this helpful knowledge as I am just starting my adventures with the venerable T1N! I have a 2004 118 Cargo base model with the "bacon" and REST buttons but no additional controls for Espar coolant heater, and no rear heater.

The 30-Rest mod sounds like a great bang for buck, so I am most likely going to do that.

But I'm still unclear on whether I can just splurge for the 7-day timer controls and just plug n' play..?
Sorry if this is already addressed somewhere, but can someone please confirm if this will work? https://esparparts.com/timer-coolant-htrs-p-25172.html

I am also considering a fancier option like programmable arduino controller or raspberry pie unit, but prefer to K.I.S.S.

Blue sky scenario is a thermostat and timer controls for Espar coolant heater, and a bonus would be to activate using aftermarket keyless entry remote (for engine/cabin preheat).

Thanks!
 

Nautamaran

2004 140” HRC 2500 (Crewed)
No, the 7-day timer is NOT Plug’n’play, though is readily added into the mix with a couple of properly placed relays.
The DPDT switch described in Post #1 is certainly a much easier way to go if your REST button blows warm air (if it doesn’t you should troubleshoot that first!)

One truism of MB is the absolute lack of pre-wiring for missing option codes.
Each vehicle has the minimum, with NO extra wires in the harness...

A typical 7-day timer setup will feed B+ to the timer, then use the output to trigger relays that switch on the dash fan, water pump, and furnace, but understand this thread before you begin and be careful not to back-feed anything!

-dave
 

marbled_rye

New member
Thanks Dave! I thought it wasn't as simple as plugging in a new espar control panel, but then I found their online store today and started to second guess.

It sounds like I'll be doing the 30-min REST mod for the best payoff. The REST button does blow air as expected, and it's just such a weird feature for MB to bother with as is, that tying the heater in will only increase the utility.
 

Nautamaran

2004 140” HRC 2500 (Crewed)
Also be certain that your coolant pump is running when the REST button is active. It’s a key component.

I’m troubleshooting/researching my REST function at the moment... prev. owner has hacked in a 7-day timer (not on my data sheet so not OEM), and I’ve recently noticed that during REST the fan blows but the coolant pump doesn’t run. Hitting the timer control momentarily activates the coolant pump so that I get a slug of hot water into the cab and 10 seconds of hot REST air before the water cools. Today I spotted a relay tapped into something off FB#1 and zip-tied up above the brake pedal... I suspect is somehow related but there are easier places to work! Not high on my list as the timer and boost buttons both work just fine.

-dave
 

marbled_rye

New member
Yes, I believe I have heard the coolant pump running when REST is activated, but I will definitely confirm before doing any mods. The REST function continues blowing warm air into the cab when activated after engine is turned off.

Still can't get over what a silly feature it is for MB to bother with. Couldn't they have just wired it in to activate automatically when the driver turns off the car but has the heat blower still activated?? :crazy:

Anyway, thanks again for the feedback.
 

outbound

06/2500/140
A DPDT Wiring Outline.....
............
........

Down at the Espar Heater connector strip off a section of harness wrap black tape.
got the new D5 installed, made sure it would fire up/run ok without messing around with the OEM config.

then ran 16/4 jacketed cable down to the D5 from under the dash/cluster, left it coiled/tiewrapped there
til can continue (its cccold today after snow yest and waiting on a new coolant pump, since the existing
unit started acting flaky... of course NOW that i need it to work... likely worn out brushes, but new pump
with new D5 only makes sen$e at this point)

Locate the BK/BL/DG aka Black/Blue/Dark Green wire. Cut that wire in a place that allows a butt connector to be installed on each side of the separated wire. Butt splice the two individual wires to your DPDT wire harness as shown on the diagram.
check/done, but cut into the van loom (not the new D5 cable, might need the wrrt at some point)
used heatshrink butt connectors (as a boat guy would)

and here's my 1st question:

Locate the BL aka Blue wire on the Espar connector. Use a tap connector to connect the DPDT harness wire as shown in the diagram.
are you meaning: splice-onto the blue wire, leaving the OEM connection intact?

Locate the Aux Electric Coolant Pump on the firewall. (Follow the heater hose off the EGR to the pump.)

Locate the DG/RD aka Dark Green/Red wire that feeds the Aux pump. Use a tap connector to connect the DPDT harness wire as shown in the diagram.
again (tho this appears straight-fwd, just to make sure):

splice-onto the pump POS wire, leaving the OEM connection intact?

That's it. No additional fuses are needed because the OEM fuses will protect what is needed.
Note: Cost can be minimized by just using wire and connectors rather than buying the items I suggested. The parts I suggested are mostly for illustration.
coool... my costs so far:
15bux for 10ft of tinned/stranded 16/4 cable, a few bux for the htshk butt conns (always have on hand)
aside from the 400 for the D5 (lucked out on that), another 65 for the new pump

Good luck.
MAHALO! vic.
altho would like to think that 'luck' aint got nuthin to do with it,
after what i've dumped into this van this year.

but... thankful that i'll be able to have 'instant heat' when out there in the outback/offgrid this winter!
:bow:
 

autostaretx

Erratic Member
and here's my 1st question:
Locate the BL aka Blue wire on the Espar connector. Use a tap connector to connect the DPDT harness wire as shown in the diagram.
are you meaning: splice-onto the blue wire, leaving the OEM connection intact?
Yes, using insulation-piercing connectors/splices:

WireTaps.jpg

They're available at auto part stores, or on Amazon (many flavors) if you search for "12v wire tap connectors"

They can slightly damage the wire you're clipping on to, and they can serve as an entry point for salt-triggered corrosion. "Convenient" isn't always "best", but it's frequently "good enough".

--dick
 

outbound

06/2500/140
Yes, using insulation-piercing connectors/splices....
...
thanks --dick!
roger that - idea being the OEM config is only 'interrupted' at pin 6 on the espar, correct?
and all other connections are spliced-onto the OEM wiring?

and thanks for the pointer on the piercing gizmos, but being a boat guy, wouldnt ever use them things
(can't believe how many eye see on 'landyachts', usually in the most difficult places to access)
 
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Aqua Puttana

Poly - Thread Finder
...

They can slightly damage the wire you're clipping on to, and they can serve as an entry point for salt-triggered corrosion. "Convenient" isn't always "best", but it's frequently "good enough".

--dick
I always dab a bit of Vaseline on the connection points before installation. Some people like silicone grease or an electrical specific product. Corrosion has never been a problem for me.

As long as the original wire is left intact, a tap connection can be more complex eg. - using solder or other techniques. For something like this I prefer KISS.

:2cents: vic
 

Midwestdrifter

Engineer In Residence
I personally stripped about 50 of those side tap splices from my parents boat 22ft ski boat. Factory installed! Several had already melted... One was feeding the bilge pump!!!

I have used the tap connectors in dry areas for low current needs (usb charger, relay trigger). Personally I prefer to just use a heat shrink butt splice, and put a pigtail on one side.

If you need them to be pseudo waterproof, filling the unit with some acid free silicone works.
 
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Aqua Puttana

Poly - Thread Finder
I personally stripped about 50 of those side tap splices from my parents boat 22ft ski boat. ...
I have never installed a piercing type connector on a boat. I've used many on vehicles with good results. Different animals.

:2cents: vic
 

outbound

06/2500/140
I personally stripped about 50 of those side tap splices from my parents boat 22ft ski boat. Factory installed! Several had already melted... One was feeding the bilge pump!!!
if the boat was in fresh, might get away with em... for awhile.

in salt?
:lol::lol::lol::lol::lol::lol::lol::lol:

its somewhat shocking how many eye see on landyachts...


I have never installed a piercing type connector on a boat. I've used many on vehicles with good results. Different animals.

:2cents: vic

exactly...
mostly since if yer land vehicle craps out, ya just pull over - and if yer lucky - call AAA..
but if yer out there and ya lose the electrical system?
could be curtains....
(just like on an airliner, its just that a boats already in the water...)
:thumbup:
 
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