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Grid heater not working

1641 Views 10 Replies 4 Participants Last post by  MGDoug3
2003. I'm getting codes P0542 and P2608. I checked for continuity for the hot wire going to the grid heater solenoids and also the wires at the grid heater. Every thing checked out so I assumed I had two bad solenoids. I replaced them but I still have the same problem. With the key on, I'm getting no power to the grid heater. I check my battery connections and all were clean.

My next plan of attack is to borrow a scanner and see if I can get the solenoids to click. Has anyone had this problem before and how did you solve it? The truck has been starting ok without the heater cycling and I usually keep the truck plugged in on a timer but colder temperatures are coming in and I may not always be next to an electrical outlet.

Thanks for any help.
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I did a little more trouble shooting. I took the signal and ground wires off the solenoids and jumped the relays and made the relays click. Next I took the intake horn off and had someone use a use a infrared gun to read the temperature. It got over 300 degrees. I forgot to take off the ground on one of the relays but when I jump the signal post, the relay clicked on. That at least tells me the ground is good.

I believe the ECM isn't sending a signal. Besides throwing a possible code, can I or is it ok to use a push button on the hot side to cycle the grid?

Edit: Or is it easier to use the ground to the push button? Maybe it's a terrible idea but just trying to think of a plan to get the grid heater to work.
Sure you can, it doesn’t matter the hot or ground side, use a push button to click in the relay.
But you have to make sure you can manually do exactly what the ECM does to operate the grid heater from key RUN, START,RUN to 15 mph.
The grid heater can sucks down both batteries easily if it’s running too long.:wink2:
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