How hard is it to replace my wiring harness

[rusty but trusty]

I have a 1987 GMC V1500 with a TBI 305 and a 700R4 trans and while searching for why my oil pressure gauge doesn't work anymore I noticed that in the main harness there are multiple breaks int the insulation behind the engine and the rest of the harness is in pretty bad shape also should I just try to fix it or buy a replacement go that route?


link for replacement harness
http://howellefi.com/tbi-harness-universal-64-trunk-length.html

[pholliday1]

If its wrong... the only way to get it "right" is to do yourself. At first putting in a new wiring harnes gives you this nice feeling inside, lets look at this. First you have to buy the harnes remove the old and install the new, sounds pretty simple? Being that either way your removing the "problem harness" I suggest fixing the old one. Not for the faint of heart, however it can be done. Your gonna need some standard electrical repair items. Solder, heat shrink, plastic wire loom, zip ties etc. Plus a good schematic. Start by disconnecting the battery, unbolting the harness from the firewall which will seperate into different circuits, front lights rear lights and engine bay.From there pull the air cleaner and start disconnecting and taking plenty of pictures and labeling as you go. From the inside you need to disconnect plugs from the ecm. And depending how deep you want to go in this process you will need to unhook the wires to the starter and the knock sensor. There are other circuits involved heater,alternator etc. This is just a small desciption of what needs to be done. Hopefully this is a boost to get you going

[bake74]

     As pholliday1 stated, in this case a picture is worth a thousand words.  I also like to take and make a hand schematic of the wiring to go along with the pic's and the printed wiring schematic.
     It seems when I have done a re-wire on anything there is always something not exactly the same as the printed schematic.

[VileZambonie]

The schematic you linked too isn't really what you need. I agree repairs are a lot easier and cost effective but a new harness is nice if you have the time and coin.

[werewolfx13]

I put a Painless harness in my '83, and while I would probably do it again if I had to do it over, I would give myself SIGNIFICANTLY more time to do it in. I planned on 3 days a few hours a day, In reality I had probably 130-150 hours in removal, cleanup, minor repair, study, planning, modification, and full reinstallation. I was under a bit of a time crunch at the end, and ended up leaving some wiring more exposed than I would like.