Engine/Transmission (1994 - 1998) Heater grid problems

[abranz]

Ive read for days all the posts on heater grids and have done my best to diagnose but need some help. My 95 is very difficult to start now the temps have dropped. Once started it smokes blue, runs rough, and the grids are not coming on. I changed the solenoids, and checked IAT sensor values which are in spec. The solenoid ground trigger wires coming from the PCM are not grounding and therefore not switching the solenoid on to power the grids. Before I replace the PCM, I wanted to get some advice.
I know I could run the trigger wires to a toggle switch but my dad drives the truck and know he will forget to turn off the toggle switch. Thanks, Tony

 

[CRodi]

Instead of a toggle switch, how about a momentary switch. I used a universal push button starter switch, easily available from an auto parts store or farm and tractor supply store. I mounted mine where the cigarette lighter used to be. I don't smoke, but I still have the power outlet available for gps, cell phone charger, etc. I wired the positve directly to the relays and ran the ground wires to the switch.

 

[abranz]

Good idea. You're talking about running a wire from ground to the push switch and the other wire to the solenoids, right? Can both solenoids be on at the same time? Tony

 

[CRodi]

That's right. I replaced both relays and wired them so that they both come on at the same time. I ran the positive directly to the relays from the battery. I don't know much about electricity, but I figured it would be safer to just run the ground wires to the push switch. I had my truck for a bout 3 years and had the same problem you did. I started by removing the air intake, and checked each grid individually by running booster cables to them. They both got red hot in a short period of time. Once I knew the heaters worked, I replaced the relays and ran the switch to my dash. I check the function ocassionally by pushing the switch after the truck starts and watching the ammeter drop. You just have to be a bit careful when working under the hood. I get clumsy, sometimes and short out the relays with a ratchet or screw driver. Nothing serious. If you get creative, you could make a cover for the relays or just get in the habit of disconnecting battery cables, or just being careful. If I could figure out picture attachments and try to send a few, but it's really simple and straight foreward. Sorry I didn'y get back to you sooner, I had guests and they just left.

Good Luch

 

[CRodi]

I started playing with the attachment feature. Not sure if they will display. I guess by know you figured, I'm not too good with computers. One is with the rubber cover threaded on and the other without. I didn't have to do any cutting or drilling. Just had to find a common washer for the switch.



Take Care

 

[GAmes]

Before you rewire the hot side, check to see if the existing wires are hot when the key is on. They should be, the PCM supplies the ground. I wired my grounds to a toggle, but I am the only one who drives my truck. If I forget to turn it off, like I did right after I wired it a couple times, the alternator gets overloaded and the PCM kicks it off line. Just stop, shut it off, wait a couple seconds and restart the engine. The PCM will reset and the alternator will work fine.

 

[abranz]

The positive small wire leads are hot when the key is on. I'm just trying to figure this out in a manner which is as fail safe as possible. Thanks so much for the ideas/thoughts. Tony