6.2 Engine Harness Repair or Replacement?

[Milblazer]

Make sure you have the correct lamp in the brake/tail lighting sockets.

#2057

But if you are good enough to restore and install a complete engine harness - and it works - I'm sure you have already checked the lamps. Right?

Old enough to try, young enough to make mistakes. Did not think I could mix up the lights. Thought I did it correctly but I will make sure according to the wiring harness. I've put this thing together in pieces. Tailight harness here, headlight harness there. I'll have to check as soon as I can. Tomorrow i'm heading to boulder to help a friend affected by the floods. Will let you know Chengy. Thanks for all your help.

 

[Milblazer]

Thought I did it correctly but I will make sure according to the wiring harness.

I meant wiring diagram.

 

[chengny]

Are either your truck or the donor truck stepside models?

The specs of the stop/park lamps for steps are different than fleetsides.

Stepsides use an 1157 lamp (single filament)

Fleetsides take a 2057 (double filament)

And the wiring harnesses are of course designed differently.

An easy fix - if that is the issue.

 

[Milblazer]

Are either your truck or the donor truck stepside models?

Negative. Everything came from one K5 or another.

 

[Milblazer]

I checked the lamps and they are in the correct sockets. I added some dielectric grease where the tail light harness hooks up to the fuse block, no change. I'm going to get some new bulbs, or better yet i'll pull out my multimeter and see where im not getting power.

 

[chengny]

For instance the rear taillights do not work, only when I step on the brakes do they work. Engine temp gauge and battery voltage are non operational

When the brake switch closes do just the parking lights illuminate? Do the side markers light up as well? What about the actual brake lights - do they come on when hitting the brakes?

I don't mean to sound condescending but, there are 2 filaments in the parking light/brake light lamps. When you apply the brakes something lights up within the lamp - but how do you know that it isn't the brake filament that is coming on?

Maybe you are not ever getting power to the parking/side markers lamps. These are also the directionals - do the directionals function?

 

[Milblazer]

When the brake switch closes do just the parking lights illuminate? Do the side markers light up as well? What about the actual brake lights - do they come on when hitting the brakes?

I don't mean to sound condescending but, there are 2 filaments in the parking light/brake light lamps. When you apply the brakes something lights up within the lamp - but how do you know that it isn't the brake filament that is coming on?

Maybe you are not ever getting power to the parking/side markers lamps. These are also the directionals - do the directionals function?

I'll have to get back to you on all that. Someone fed the gremlins after midnight and now I have absolutely no power anywhere. I had the headlights on to see if they were aimed in the same direction. Went to start, turned the key so the glow plugs would cycle, then nothing. The headlights would not function, do dash lights, not even the door buzzer. I had installed two brand new batteries the same day, checked and they were at 12.80 volts and 12.81 so the problem is not there. Battery cables are brand new as well. I'm going to go through a shop manual I have to see if anything catches my eye.

 

[Milblazer]

I hooked the batteries back up, tried turning the key and got dash lights but no glow plug solenoid clicking, no starter turning over. Pulled out the multi-meter and probed around to see where I was getting power. Power was available at the fuse block and to the glow plug relay. I turned the key on re-probed everything. When I got to the blue wire on the glow plug solenoid it snapped to life and about scared me out of my shoes. Starts fine now, lights work. I have no idea what went wrong, possibly a bad glow plug solenoid? Anyway I started working on my tail light problem with the multi-meter. Started from back to front. I could not get a steady voltage anywhere so I went to the fuse block and removed the rear tail light harness. I then turned my vehicle back on and check the voltages while grounding to the driver side battery. With the lights off there was minimal voltage, every one of the four sockets measured in the millivolts. With the lights on I still was not getting any voltage to the rear. With the directionals on I would get anywhere from 0-20 volts which seems a bit high.

 

[Milblazer]

Haven't updated this for a while and I wanted to let you all know whatever the problem was it seems I have figured it out. After losing power I pulled the engine harness back out and did some researching. Since I was getting no power anywhere I focused on that and came to the conclusion that the fusible links that hook up to the starter could be bad. I cut them off and soldered some new ones from napa on. While the harness was out I took all of the caps/protectors off every wire and cleaned up the contacts with some sandpaper to make sure everything was getting power. I reinstalled the harness and before I hooked the battery cables back up I added one of these little buggers to my positive battery cable on the passenger side as my cables were ac delco and did not come with it. I saw scorch marks on one of the cables where they attached to the side terminal. This is GM 12354951.

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After all of this my truck fired right up and has not had a power issue since.