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Grid heater not working

1640 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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Before I started the test procedures, I throughly cleaned all battery and ground connections. Next. I went through the test procedures and didn't solve anything. On step 4, I didn't disconnect the ECM. I wasn't sure if that meant the ECM on the motor or another one. I have an Edge Insight and was worried about clearing out my maintenance schedule before I wrote it down.

I did disconnect the negative battery cable and check the ohms between the signal wire and negative battery post which read 140 ohms. Not sure if this is correct or not since I didn't disconnect the ECM harness. Can someone clarify if it is the ECM on the block?

I started the truck and checked all the battery cables for excessive heat and everything is ambient temperature checked with a temp gun.

It seems odd that the grid heater would go out all of a sudden. I tried to clean the ends that hook to the actual grid heater but the bolts feel like they're about to twist off and I'm afraid I'll snap the bolts off.

Truck is sitting outside in the cold so I decided to stop and report back. I plan to do a little more research tonight and pull the truck inside tomorrow. I'll borrow the scanner tomorrow as well and see if I can get the relays to click.

Luckily the truck does seem to start fine in the cold until it reaches the teens or below. I usually like to keep the truck plugged in just because it's easier to turn over.
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I disconnected the battery cables and the two connectors at the ECM and ohm'd out the signal wire to the battery. Both signal wires (one on each relay) measured 100K ohms. Since it's not greater, I'm assuming it's in the wiring?
I went over all the wires and checked all the connectors I could find. I didn't see any broken, bare or corroded wires or connectors. I put everything back together but in a heated shop the air temperature was too hot to try to kick on the grid heater. After the truck sat outside for a bit, the codes came back.
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.
Thanks for the feed back. I figured I could use less wire grounding the switch. I was going to use a push button so the grid is only on when the button is pushed in. I've read how people used a manual grid heater before but that was on older trucks.
I ended up and wired into the hot side of my gauge lights since it would save wire and already has a fuse going to the battery. Wired it up, pushed in the button and the relays came on. Everything seems to be working but it does throw two codes (P0541 and P2607 I think). The check engine doesn't come on though. That's good enough for me.

I did have someone earlier turn the key on for me while I checked voltage to the signal side of the relays and it was almost zero. I would like to thank everyone who helped me troubleshoot.
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