Ok, I finally got time to check out my grid heater system... I am getting no power to the hotside of the selinoid/relay coming from the harness... What should I check... I don't know where the power is supposed to come from besides the harness... I went out and checked my dump truck and it is good.. there is constant power to the relay/selinoid and when the key is cycled the other side is hot and it travels to the grids... So, what do I need to do??? I'm sure it is something simple, but I'm stumped... Does one of the 3 relays on the side of the fender have anything to do with it... thanks

 

I think there is a fusable link inline with the power to the grids. It will look simular to a butsplice thats been heat shrinked, thats the fusable link. If you have a good meter with sharp tips you can just poke through the insulation before and after the fuse link and see if its bad. That would be my best guess. The grid relays are controled by the computer so even if there is no power on the grid side of the relay the computer should cycle them. Are they closing when you cycle the key?

 

Ya...both are clicking when the key os cycled and when the light goes off they click again...There is just no power at the hot side of the selinoid... I'm pretty sure it should be hott all the time... at least thats how my dump truck is...

 

yes it should be hot all the time. the only thing left is fusable link or a break in the wire. The wire should be a 6awg and connected to the battery with the main hot cable.

 

ok.. I will get to unwrapping all my nice electrical tape job But, the funny thing is I disconnected all the extra leads off the positive side of my dumptruck and it was still hott on the one side of the selinoid... so That had me wondering?? Thanks for the info..

 

Bump to the evening crowd!!!

 

what year of truck is this on and are the trigger wires connected securely? i have a couple loose trigger wires on mine and i need to fix it.

 

I have a similar problem. On my 89 both of the solenoids have a hot side all the time, but when I turn on the key nothing happens. There's no click, the other sides of the solenoids are not hot on the odd side. What in the world can be the problem. Tonight I was testing for hot sides and I looked in cab and the wait to start lite was blinking. I am beside myself trying to figure this out. This is day 5 of working on this. On my 93 only one of the solenoids is hot all the time.

 

The solenoids are controlled by the PCM/brain box grounding one terminal. The other terminal is supplied with 12 volts when the key is on. The power side of the relays gets power straight off the battery through a pair of fusible links.

edit! Wrong! on a non-intercooled truck it is backwards, the brain box switches the power to the control side, the other terminal should always be grounded.

Sounds like one fusible link is blown on the '93.

Blinky WTS light means the air temp sensor circuit is open. Could be a bad sensor, bad connection, or a broken wire.

 

Wanna, I was hoping you would come in. Where is the air temp sensor circuit sensor? When I turn the key on, the other side of the terminals don't become hot.
I thought they should and I can't seem to figure out why. Any ideas?

 

The air temp sensor is screwed into the side of the manifold below where the crossover tube mounts.

I made an error back in post #9, go back and read the edit.

 

So do you think the sensor is bad? When I turn the key on should the other 2 sides be hot or not?

 

With the key off, your '89 should always have power to one large terminal on each relay, and the black wires off the small terminals should be good grounds. When you turn the key on (assuming it's cold enough to need the grids), you should have power on the small "not black" wires, and assuming the contacts inside the relay are good you will have power on both large terminals.

Early production '89's do not turn the grids on until 15 degrees F, you may have one of those trucks. Look at the serial number on the brain box, if it is lower than 0080000A then it's a 15 degree unit.

 

Thanx Wanna! It's 40 here, so that could be the case. I now have dash lights, but I have a huge draw somewhere and again I'm stumped.

 

So...Is it best to replace the fuseable links with a inline fuse?? I haven't had time to look into mine yet, but I'm sure it is the problem... I like what was done in the sticky, just affraid of all the electrical work!!