A buddy just picked up a '98 24v CTD. Problem is the grid heater will not energize. I checked the fuse for it and swapped the relay for the heater and the blower motor. still no power to heater. I checked continuity at the heater, it is good. I checked power to the 2 solenoids(below the drivers side battery) that supply power to the heater, I get 12vdc to one side of the solenoids but nothing out with key on. the rear wire on the solenoids are grounds, good there. the foward wires I can only assume are for incoming 12vdc to activate the solenoid, but no power there. I can hot stick the solenoids and make them energize, so they are still good. The question is, what controls the solenoids and where is it? thanks guys.

 

I am not sure what controls the solenoids, put I had a similar problem with a grid heater not working on a 97. I took it in and they replaces the relays I think, it took care of the problem. Not sure if that is what your problem is but it is worth a check.

 

I believe the solenoid windings are grounded by the PCM and I assume powered by the ignition switch. Check all the maxi fuses. Never really seen a problem with the control power circuit before. Make sure the IAT sensor is inputting to the computer properly.

 

I also have that problem, try unhooking the negative cable from batteries for 30 mins, that fixes mine for awhile. I was also having the TC lockup problem, I put a noise filter in, and so far that has cured both problems, but only on day 3, so a few more days to know for sure. Also if you do find anything I would like to know.

Clint