REST/Booster Engine Pre-heat with DPDT Switch Modification

norths03

New member
I'm finally getting around to doing this mod. If I don't use the REST/BOOSTER functions normally could I just hide the DPDT switch and leave it activated and just push the REST button when preheating or would leaving just the DPDT switch on cause a battery drain or other issues?
 

220629

Well-known member
I'm finally getting around to doing this mod. If I don't use the REST/BOOSTER functions normally could I just hide the DPDT switch and leave it activated and just push the REST button when preheating or would leaving just the DPDT switch on cause a battery drain or other issues?
It probably won't work that way. The electric coolant pump power and REST timeout is what I leveraged for the Espar to run for engine preheat.

The problem with your idea is that the Aux Electric Coolant Pump is energized/powered anytime that the engine is running. Leaving the DPDT switch in the full time Espar enable (preheat) position would have the Espar firing up whenever the engine was running.

The Espar would supplement the engine heat until the Espar combustion module coolant temperature monitor was satisfied.

vic
 

norths03

New member
It probably won't work that way. The electric coolant pump power and REST timeout is what I leveraged for the Espar to run for engine preheat.

The problem with your idea is that the Aux Electric Coolant Pump is energized/powered anytime that the engine is running. Leaving the DPDT switch in the full time Espar enable (preheat) position would have the Espar firing up whenever the engine was running.

The Espar would supplement the engine heat until the Espar combustion module coolant temperature monitor was satisfied.

vic
Thanks, that makes sense. I'll just plan to flip the switch when it's needed. So if I let the lady friend use the van and she forgets to turn the switch off after preheat (she forgets to turn off the interior lights and kills the battery more often than I'd like so this is a real possibility), would she be at risk of draining the battery when the van isn't running or just at risk of running the Espar whenever the vehicle is running? Is there a failsafe that could be added to help the forgetful types with this?
 

220629

Well-known member
Thanks, that makes sense. I'll just plan to flip the switch when it's needed. So if I let the lady friend use the van and she forgets to turn the switch off after preheat (she forgets to turn off the interior lights and kills the battery more often than I'd like so this is a real possibility), would she be at risk of draining the battery when the van isn't running or just at risk of running the Espar whenever the vehicle is running? Is there a failsafe that could be added to help the forgetful types with this?
I can't help with interior lights and memory.

If the DPDT switch is forgotten it will just run the Espar heater while the engine is running. That will add service hours to the heater, but won't hurt anything. The Espar combustion control module will shutdown heat when the engine is at operating temperature (above 167F coolant temperature). (I'm quite certain that 167F is the official Espar setting, but may be a bit higher or lower in practice.)

If the switch is left in Pre-heat position it will not drain the battery.

vic
 

norths03

New member
I can't help with interior lights and memory.

If the DPDT switch is forgotten it will just run the Espar heater while the engine is running. That will add service hours to the heater, but won't hurt anything. The Espar combustion control module will shutdown heat when the engine is at operating temperature (above 167F coolant temperature). (I'm quite certain that 167F is the official Espar setting, but may be a bit higher or lower in practice.)

If the switch is left in Pre-heat position it will not drain the battery.

vic
Thanks again for the quick reply. That's great news about it not draining the battery. I don't mind putting additional hours on the OEM Espar so that shouldn't be an issue. In fact there may be a real benefit to leaving the switch on since the Espar is supposed to be run monthly anyway for maintenance. We typically only use the van a couple of weekends a month so we're at risk of not running the OEM Espar enough as is. I'll consider it my winter/Espar service switch and leave it on at least through the winter and possibly the summer for maintenance purposes.
 

kkanuck

LUV my T1N
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!
Old thread but curious if you fed a wire to the OEM rear heat switch you utilized for this mod with an illumination feed so the switch is illuminated at night?

I want to use the DP3T Ventilator switch to create this rest mod and keep the factory look. So I run the 4 wires to the Espar unit outside from the center dash, and a wire to the illumination circuit, which I just located and used adding a high idle switch incidentally by tapping into the ATC wire loom. Do I still have to add a ground wire as well, and if so which pin does one attach the ground to and which the illumination circuit, Pin 1 and pin 10, which wire to which terminal?

Thanks in advance any assistance. Screen Shot 2021-04-21 at 12.44.25 PM.png
 
Word of caution!
Never use aluminum wires for this modification. USE COPPER WIRES.
I tried to turn on the preheater at 25F(Not needed at 25F but I regularly run espar heater) and REST light goes off after about 20 seconds repeatedly. I checked the voltage and it was round 12v. After driving around at 12.5v, preheater works again. Same thing happens overnight at low voltage. I replaced aluminum wires with 14 gauge copper wires. Now it works at 11.9v and below. Just my 2 cents.
 
hello, if i have a 06 3500 and i do have the espar in my wheelwell, but the warm up button on my dash, in between the bow tie, does not light up or do anything at all. is this a good indication that the switch is bad or the heater?
 

ECU

2006 T1n 118 Sprinter
The center bow tie button only works when the engine is running.
Do you notice the button actually moves? Some have just a placeholder and no button.
Does the REST button work?
It is more likely that the light is burned out than the switch is bad.
 
well i do believe i have the version where the center bowtie button is a placeholder. so i have the heater but i really dont know what it does. the rest function works after the van is turned off. it appears the set up described in this thread is what i need to do. the whole 7 day timer system. i did just install a planar 2D in the rear of the van so i have house heat. i would like to get the factory espar to pre heat the engine at least.
 

ECU

2006 T1n 118 Sprinter
I don't know why you would have a heater and no method of operation. Maybe you had a 7-day timer?
The REST works only when the engine is off.
 

Cheyenne

UK 2004 T1N 313CDi
well i do believe i have the version where the center bowtie button is a placeholder. so i have the heater but i really dont know what it does.
Post photos of the row of three heater control knobs and also the switches alongside your gear shifter and someone will tell you what does what.
 

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