Has anyone tried this. I installed a Webasto Preheater in my 2011 Ram with a Cummings. I hooked up the Webasto to the interior blower motor. This truck has the manual temperature control system. When the Webasto is running and turns on the blower motor only cool air comes out of the floor vent. If you turn on the ignition you can here the blend door move to the hot position.
Does anyone know if you can program the blend door to stay in the hot position with the ignition off.

 

There is no such programming feature. The only thing you could do is find the wires for the blend door activation and add a diode isolated relay to the circuit so it has power when the preheater is activated. Wiring in the newer 2006+ tipm controlled trucks is kinda dangerous as everything is canbus and multiplexed.
It's a little more involved than just a relay as you would need a toggle switch as well. The toggle switch would be for warmer weather so your air conditioner would work properly. Otherwise, you would get the engine heat while trying to obtain A/C.

One other option would be to provide power directly at the ignition with a relay. This may cause some of your dash lights to illuminate and would definately cause your blower motor to activate. The heater circuit is 60A I believe so it would drain your battery if left on for any extended period of time, even if the blower was left on low but if you were to have 2 batteries you would be fine. I think this is probably your option if you plan to use the oem blower motor.

 

Cummins.

 

I thought about a relay for the blend door motor. I have put the Webasto's in plenty of diesel's from 2000 to 2007 Rams, GMC, and Fords. Everyone of these trucks when you turned of the ignition the heating systems went to the floor and the door went to hot. Figure's they would have to change things. I got spoiled whith my other truucks having the cab heated in winter with the Webasto. It sure is nice in -40 to get in a warm truck first thing in the morning. I am going to take a look at the control's this weekend and see what I can come up with.

Thanks for your input.

 

Well, you can't just T-tap the line with a relay. You MUST cut the wire going to the blower motor and insall the diode within that line. Then, you would hook up the relay controlled power source to the blowerside of that line. Otherwise, you'll send power to the tipm which would cause canbus issue's and could fry something. You would also need a didode in the relay line going to the blower motor as well. This is the peoper way to diode isolate one circuit from another.
You'll probably need to do the same with the ground as that is computer controlled as well.
Well, thats what I have a remote starter for ;-)

 

I have 2 relays running the blower motor and it works fine with no back feeding. I think I am going to tre the same for the blend motor.

Car staters work fine if you don't mind idling.

My GMC I just sold was 04 with a Duramax 345,000 miles and only 4325 hrs on the engine. I don't think you could keep your engine hrs down like that with a car starter.

Ron