Help with rear light harness

[crashmod]

I recently replaced the rear light harness on my 85 k10 and need help with finding the right connector for the intermediate harness. Basically the previous owners did a pretty bad hack job of the wiring on this truck adding accessories al over the place so some of the wiring bad to be rewired or completely replaced. It is an LMC rear light harness 36-3101 and they claim it is a factory original connector that is on it. Its actually a pretty decent harness from them. Problem is the previous owners replaced the wiring connector on the back of the truck and done away with the original connector. I would Ike to be able to find the right connector that plugs into the harness instead of having to cut it and rewire it. Does anyone know who the manufacturer of this harness is or know where Incan find the right connector for it? Any help would be greatly appreciated.

[ray_mcavoy]

I believe GM changed the intermediate to rear harness connector sometime around 1984. The one you have pictured appears to be the earlier style. The 84+ ones use a Weatherpack connector that has round pins.

To get matching connectors without any cutting or splicing I think you'll have to purchase a pre-84 intermediate harness that will have a molded-on connector that will mate with the one in your photo. I don't think those molded-on connectors are available separately as a new replacement part. And even if you were to salvage one off an old intermediate harness you'd still have to cut the wires and make inline splices.

The other alternative would be to exchange that new rear light harness for one that has the 84+ type connector. Then you could purchase the mating Weatherpack connector and install it onto the end of your existing intermediate harness (assuming the previous owners didn't cut the wires too short).

[crashmod]

The harness that I installed is actually supposed to be for the 84+ model trucks. I'm guessing they are sold with the connectors like that so you have to buy the intermediate harness as well. Unfortunately the intermediate harness and other wiring is bad as well. What started all of this is I have an issue with the dash lights and front marker lights coming on when I hit the brakes and when I had the headlights on I had no brake lights. So I am assuming it is a ground issue somewhere along the lighting system. Ive replaced all the switches which was probably needed anyways and checked all grounds and when I checked the wiring under the body I noticed a lot of tape and house wiring nuts. So all of that had to go. Ive got a new weather pack connector that in was planning on using if by chance I couldn't find a connector that would work. Downside the new rear harness has 6 wires feeding the taillights now and I was not looking forward to having to figure out what everything controls and splicing it together but it is doable.

I also have another question about wiring. There is a brown wire with white stripe that runs under the dash in the wrapped up wire loom. It has a solid wire core no strands of copper. Driving the truck awhile back and the dash started smoking and then it quit. Drove it home tore the dash apart and couldn't find anything so I had to drive it with a pair of wire cutters in the seat until it done it again and I found it by grabbing the harness and just cut the wire that was extremely hot. It doesn't seem like it affected anything in the truck but I'm not sure what it was going to if anything.

[hatzie]

Originally Posted by crashmod

The harness that I installed is actually supposed to be for the 84+ model trucks. I'm guessing they are sold with the connectors like that so you have to buy the intermediate harness as well. Unfortunately the intermediate harness and other wiring is bad as well. What started all of this is I have an issue with the dash lights and front marker lights coming on when I hit the brakes and when I had the headlights on I had no brake lights. So I am assuming it is a ground issue somewhere along the lighting system. Ive replaced all the switches which was probably needed anyways and checked all grounds and when I checked the wiring under the body I noticed a lot of tape and house wiring nuts. So all of that had to go. Ive got a new weather pack connector that in was planning on using if by chance I couldn't find a connector that would work. Downside the new rear harness has 6 wires feeding the taillights now and I was not looking forward to having to figure out what everything controls and splicing it together but it is doable.

I also have another question about wiring. There is a brown wire with white stripe that runs under the dash in the wrapped up wire loom. It has a solid wire core no strands of copper. Driving the truck awhile back and the dash started smoking and then it quit. Drove it home tore the dash apart and couldn't find anything so I had to drive it with a pair of wire cutters in the seat until it done it again and I found it by grabbing the harness and just cut the wire that was extremely hot. It doesn't seem like it affected anything in the truck but I'm not sure what it was going to if anything.

The easiest soloution is to source an unmolested 1973-1984 frame-to-taillight harness that will plug into your frame-to-cab harness.

The second best way to handle it is to replace the molded connector with the 85 up weatherpack connector.
This inexpensive tool will make adequate crimps on Weatherpack terminals. http://www.amazon.com/gp/product/B002CCAEJ6/ref=pd...
This inexpensive tool will make adequate "W" crimps on Packard 56 and other terminals. http://www.amazon.com/Open-Barrel-Style-Crimp-Tool...
If you intend to do a lot of wiring professional quality ratcheting crimp tools can be had for around $100 each. They can be re-sold when you are done because they hold their value fairly well if they look reasonably new.
I've bought professional level ratcheting crimp tools from The Electrical Depot for pretty reasonable prices. He has other tools, terminals and, connector housings in prototype/hobby quantities for fairly inexpensive prices. If you're only going to crimp 15 terminals and have done except for small odd jobs just get the less expensive tools... $60 vs $200-$250.
I usually use crosslink poly "XL" wire for everything. It's identified by prefix letters corresponding to jacket thickness TXL, GXL, & the thickest SXL. You can get assorted colors in "hobby" quantities of 25' lengths on Fleabay from "The Wire Barn" among other sellers. Most suppliers that will sell to hobbyists like us... Del City, Waytek, Etc "small spools" are 100' and mostly sell 250' & larger spools. Unfortunately The Electrical Depot only has PVC jacketed wire as of this writing.

qty 5. #12089188-L Delphi Connection Systems Automotive Connectors FEMALE Tin Plated Terminal, Cable Range 0.50 -0.80 mm²
qty 5. #12089040-L Delphi Connection Systems Automotive Connectors MALE Tin Plated Terminal, Cable Range 0.50 -0.80 mm²
qty 10 #15324982.. Delphi Connection Systems Automotive Connectors INDIVIDUAL LOOSE CABLE SEAL GREEN
qty 1. #12015798.. Delphi Connection Systems Automotive Connectors 4P FEMALE BLACK 20 AMP WEATHER PACK PLUG
qty 1. #12015024.. Delphi Connection Systems Automotive Connectors 4P MALE BLACK 20 AMP WEATHER PACK SHROUD

If you need to replace the 4 wire frame harness use these Packard Series 56 terminals at the bulkhead plug. Enclose the wire in split poly loom.
qty 5. #8911677... Delphi Connection Systems Automotive Connectors Series 56 Long Male Unsealed Tin Plating Tang Terminal, Cable Range 0.50 - 0.80 mm²

GM Circuit numbers on this diagram snipped from the 1985 wiring manual.
Ground #150 NOTE: On the fleetsides each tail lamp assembly grounds to the bed side and the license plate lamp has its' own ground. I usually run the grounds direct to the frame for reliablity.
Backup Lamp #24
LH Turn #18
RH Turn #19
Park/Side-Marker/License Lamps #9

NOTE: You don't need a disconnect at each taillight unless you want one. Use the E62/E63 single Weatherpack pinout to keep it compatible with things like trailer harness plugins. Check your year wiring manual for the correct "bulkhead conn" pinout and wiring colors as it may differ from the 1985 pinout shown.

[crashmod]

I just want to say thank you for the help with this. It looks like I have finally found a forum that is helpful and can provide great knowledge on repairing my 85 k10. I'm not exactly new to rewiring and the information you provided is well appreciated. Hopefully I can get back started on it this weekend and sort everything out.

[ray_mcavoy]

Originally Posted by crashmod

I also have another question about wiring. There is a brown wire with white stripe that runs under the dash in the wrapped up wire loom. It has a solid wire core no strands of copper. Driving the truck awhile back and the dash started smoking and then it quit. Drove it home tore the dash apart and couldn't find anything so I had to drive it with a pair of wire cutters in the seat until it done it again and I found it by grabbing the harness and just cut the wire that was extremely hot. It doesn't seem like it affected anything in the truck but I'm not sure what it was going to if anything.

That solid core brown wire with the white stripe sounds like the "exciter" wire for the alternator. It provides the initial field current for the alternator when the engine is first started. It's circuit #130 if you look it up on the factory wiring diagrams. At the firewall bulkhead connector, it connects to circuit #25 (a regular stranded copper brown wire) in the engine harness that leads to the alternator.

The reason for that wire being solid core is because it is a special resistance wire. Approximately 2Ω per foot and about 5 feet long for a total resistance of 10Ω. It basically takes the place of the "GEN" light bulb in trucks with factory gauge clusters.

That wire getting hot and smoking sounds like there may be a short to ground somewhere along the circuit #25 brown wire in the engine harness. Or possibly an internal alternator fault. And with that wire disconnected, you will likely have issues with the alternator not charging, especially at lower engine rpm. Unless someone has installed a "1 wire" alternator that would still charge okay without that wire hooked up.

[crashmod]

That may explain why at one point the volt gauge was only showing 10 volts at times but would jump back up to around 13.5-14 volts once the motor went over 2000 rpm's. The motor is out of a 92 model truck but I can't remember exactly what alternator I used. I believe it is a 1-wire but I went ahead and hooked it to the original factory wiring instead of using just a 1 wire hookup. I'm slowly going through the wiring on the truck trying to chase down all of the wiring issues that it has. Almost to the point of just buying a new wiring harness and starting over.