stonewalldiesel

Hey Guys, I need some help here can't seem to figure this one out. It all started about 2 weeks ago. I had another VP44 installed on Warranty. Got the truck home and I checked just for the hell of it to see if there was any codes . There was the 0380 code which is the heater relay #1 not working. Also overboost code came up. I took it back to dealer and they diidn't know why so they cleared the codes. Bear in mind I had all my mods off the truck because of the warrranty work. I installed all of my mods again and all is well until a couple of days ago when I got the 0380 and 0382 codes which is the heater relays 1 &2 not working. I just replaced the solenoid pack in March so the odds are slim that this is the problem. I removed solenoids and tested them this morning. The triggers are working and the solenoids are functioning. To confirm I ran 2 wires to battery from the trigger studs and hooked a meter to the main wire leads that are supposed to go to grid heater. When solenoid fires the circuit opens so they both are working fine. I checked leads to grid heater conductivity is good no broken internal wires. I reinstalled solenoid pack and tested with engine started. the solenoids are firing but no voltage is going to grid heater. I also pulled IAT sensor and checked ohm's that is all good. I removed grid heater and checked continuity that seemed OK also. I got 12V reading on the power side of the solenoid but nothing coming out.?????? These are only a few months old. I just can't believe that there bad. Even after all the testing I did theoreticlly it should work. I am at a loss. Unless there is a fuse somewhere that is inline with the power leads going to the grid heater. Is there??????

infidel

If you are getting juice to the output side of the solenoid when triggered the only problem can be the grids themselves or the wires to them.
Are you getting power right at the grids?

stonewalldiesel

No I did not get any power to the grids

VADSLRAM

You answered your own question. If you got power going in but not out then the problem is at the end of the trail.

stonewalldiesel

If you read my thread originally, I tested the solenoids and they work finr and what are the odds of both being bad????

shortround

There is 2 black wires, that supply power to the grids, that hook to the driver side battery. Make sure they are connected. Both wires connect into a single lug. After my wreck, the body shop connected those wires to a ground just below the battery. Everything for the grid heaters worked, just no power to them. Didn't notice the problem until the temperature dropped and the engine was hard to start. The wait to start light will function normally.

Shortround out

stonewalldiesel

Thanks for the info. I checked all the harness wires this A.M. all is good. I pulled the grid heater and checked continuity through the elements and that checked out good . I then hooked up the grid direct to battery and both elements worked fine. I disconnected the firing wires from the solenoids and manually wired to battery the triggers fired and I had power to grid heater on both solenoids. Soooooo!!! Whatever fires the solenoids is what must be the problem. Where does the signal come from to fire the solenoids. IAT sensor??? I checked it the other day but I got readings at room temp. 13 ohms but no lower. I put a heat gun in front of it and the ohms were climbing so I assumed it was working properly. I did notice this AM that after I got to the city approx. 1/2 hour drive I stopped the truck for a few minutes to get a coffee. When I started the beast the grids fired as I noticed the amp meter cycling. I wouldn't think that the grids would fire on a hot engine. Any other suggestions would be greatly appreciated.

infidel

Sounds like a computer glitch in the PCM or a bad connection between the IAT sensor and the PCM. A bad connection should throw a code though.
Try "rebooting" the pcm by disconnecting both batteries for a half hour or so with the key on.

stonewalldiesel

Thanks., I'll give that a go. I did have the batteries disconnected this AM when I was testing everything but not with the Key on. Does that do the reset????

Sidewinder

The key on doesn't do the reset but it makes sure that any capacitors that might hold a charge are completely discharged when the batteries are disconnected.

stonewalldiesel

Thanks, I'll give that a try. I started the beast this AM and the grids were working as far as I could tell as the amp meter was cycling up and down. So maybe I corrected it after all. We'll see over the next few weeks.