2003 Ram 3500 HO

I am far from home in the Pacific Northwest with a problem and need to disable the grid heaters. It is raining 24/7 so I am looking for the cleanest/quickest way to disable the heaters.

I found reference to a fuse that controls power to BOTH grid heater relays (solenoids) but I don't know where it is located in my fusebox. (The coils are "hot" via this circuit and the PCM grounds the other side of the relay coils to activate the relays)

Can anyone help with a fuse location?

An alternative is removing the fusible link wire (that feeds the heater relays on the engine block) at the battery terminal, but I don't SEE a separate terminal connected to the battery terminal that can be removed. The terminal has several wires molded into it that cannot be removed, however.

Any help to disable this circuit w/o having to climb into the engine compartment would be most appreciated.

Thanks-

 

Why do you need to disable the heater grid?

 

According to the schematic on alldata, the grid relay coils are chassis grounded, and receive power from the pcm. Of course, they don't show any circuit protection devices at all either.

 

My after-market lift pump was acting weird while the grid heaters were cycling, so I wanted to isolate the heaters to see if that WAS the cause.

 

Interesting-

A diagram I saw showed one side of the grid relay coils supplied 12v through a fuse, and the other side grounded through the PCM, thereby closing the main contacts to supply 12v from the battery through the fusible link to one side of the grid heater elements, the other side being grounded, thereby activating the heaters.

 

I have a fass 150 lift pump. No issues. What kind of issues you having? Could be how the pump is wired. IE, where is it getting power.

 

Yeah the diagram I'm looking at shows the relay coils grounded chassis side, with power from the ECM at pins 5&6 on connector C2.