Engine/Transmission (1998.5 - 2002) No ECM signal to grid heater solenoids

[Bulldog80]

Thanks to the guys on this forum I finally got my 99 running with an 01 motor in it. I'm now figuring out that somewhere along the way the grid heaters stopped working. I thought that it was going to be bad solenoids so I replaced them but it's still not working.



I've got power to the battery side of the solenoids and grids themselves are grounded and in good shape. It sounds like from everything I've read on here that the ECM is supposed to trigger them after getting a reading from the IAT sensor. So, I thought it was a bad IAT and replaced it. Same thing, no signal to the solenoid. Has anyone else had this problem or can tell me what else to try?

 

[Bulldog80]

Anyone have any ideas?

 

[Bob Wagner]

is your wait to start light working?

 

[Bulldog80]

It comes on Bob but doesn't seem to stay on very long. I've got the truck plugged in so I don't know what effect that has on the duration. My 01 is plugged in right next to it in the same environment and seems to cycle longer no matter what.

 

[CToney]

Wire in a push button switch that is only on when you push it. Wire it to the trigger side of the relay that way if you need heat just push the button for a bit and then start her up. The grid heaters don't need to cycle after the truck is running. My 93 wouldn't cycle if it had been plugged in and it wasn't that cold out. My 97 wants to cycle every time I start it no matter really how cold it is. It cycles longer when its colder.



CR Toney

 

[Bulldog80]

That would obviously work CToney but it hasn't always done this. There's got to be a reason it's doing it. They aren't cycling even if it's not plugged in. I'm just plugging it in now so I can start it in a reasonable period of time. Did you ever diagnose the problem on your 93?

 

[CToney]

I didn't think it was a problem. The elevated water temp from having the block heater plugged in raised the intake air temp high enough that the heaters didn't need to cycle. It was the same on both 93's I had. When the block heater on my first 93 quit I bought one from cummins it was smaller (must have been for a 4cyl) and my grid heaters cylced way more returned it and bought the right one 750w. Then the heaters quit cycling. To me that is the way it should be. 0C to -15 C Grid heaters shouldn't cycle if plugged in and depending on the wind they should cycle below that to aid in starting. My '97 wants to run the grid heater too often in my opinion but I have an oil pressure shut off switch to disconnect the grid heater once I have oil pressure. Once its warm out I pull off the trigger wires so the heaters don't cycle at all. So my relays, alt, and batteries will last longer. Our tractor with a 5. 9l doesn't have grid heaters an she starts just fine down to -40 but she's out of the wind. Check the wiring you may have a loose connection going to the sensor or ecm.

 

[Bulldog80]

If it was warmer out I think I'd agree with you about not needing the grid heaters. It's been really cold here of late and even parked inmy shop and plugged in it's still cranking a little longer than I would like. What's funny is, and I might have already mentioned it, but my 01 is parked right next to this one and plugged in too and it cyles the grid heaters every time and fires right up. I know theres something wrong with the 99 cause even unplugged it doesn't cycle. I'll check the IAT wires. If anybody else has any other ideas I'm all ears.

 

[ROADWARRIOR]

Did you ever find your problem?



Dan

 

[Bulldog80]

No, I never could find the problem. My answer was to trade in the truck. I swapped the IAT sensor, in fact, almost all of the sensors and I couldn't get the grid trigger signal from the ECM.

 

[NoSeeUm]

No, I never could find the problem. My answer was to trade in the truck. I swapped the IAT sensor, in fact, almost all of the sensors and I couldn't get the grid trigger signal from the ECM.

You traded your truck? For what?



Jim