1meanGTA

my wiring is pretty old anyway, but the last guy to own the car kind of hacked it up. some of the underhood harnesses are tapped into all ghetto for testing, lot of little sloppy stuff like that. also, i had an intermittent problem where i would pop the ecm/fuel pump fuse that eventually ended up burning up my custom ecm. i think the dash wiring has problems also, the lights on the dash will go out sometimes, come back on if you smack the top of the dash just right.

i'm thinking my best bet may be to tear it all out and put in fresh wiring. i would be looking at ordering both the underhood and dash painless wiring harnesses to redo it all, right? what other options are there? i know i can save a few bucks at the junkyard or classifieds... but as much work as i'm going to put into doing this rewiring job, i think unless i can put eyes on a really nice condition set, i want to stay with new.

im planning on doing my own PROM burning after i get the wiring issue all sorted out, and at the same time, i'll be looking at possibly swapping my stock tpi intake (ported) to a HSR or a miniram. do i need to take any of this into consideration when i buy my harnesses?

Drew

iTrader: (58)

Your dash lighting problem is probably the dimmer module or the headlight switch. You're not going to find a generic street rod harness from Painless or another provider that's going to do the job that your factory harness did. You would be further ahead to consider looking for a donor harness. If you can find someone parting the same year, make, model, car with similar options the harness should be the same. Fixing what you've got now would be the easiest and cheapest option. If it were me I'd get a GM/Helm service manual for the car, a soldering iron, solder, and some heat shrink tubing, then clean up and repair the existing harness. It's not that difficult, just time consuming.

Changing the engine harness is fairly easy, just time consuming. The dash harness is a bit of a nightmare in comparison. I'd rather fix wiring problems 10 or 15 times then pull the complete dash harness.

Pocket

iTrader: (24)

Dont mess with the dash harness unless you have to

radical82

I've done a couple 3rd Gens for customers using the Painless harness...If you're going aftermarket on the wiring, it's a good way to go. Also did the last one with an OEM harness from the U-Pull-It yard--had to look at a bunch of cars to find a decent harness that wasn't all hacked up, but I eventually found one... Nothing really difficult about the rewiring if you have a good quality schematic. I actually prefer using the Painless harness as it has provisions for add ons and accessories... Whichever you use, it's a very labor intensive process--don't expect to get it done on a weekend!!!

1meanGTA

oh, i knew it was going to take some time. i'm planning on having the car down at least a couple more months, it hasnt been driven in years so it's no big deal.

so the dash is probably something simple... its had an alarm installed with t-clips, but its not in anywhere near as bad of shape as the underhood wiring. i do have a 1987 service manual and know wiring (used to install alarms and audio) so the work itself wont be over my head or anything.

i'll probably still be looking at swapping out the whole underhood harness, as bad as it is. the main thing i'm concerned about is that i probably still have an exposed wire someplace near a ground in my ecm/fuel pump wire, because it used to pop that fuse up by the battery all the time and eventually my ecm blew out. i looked and looked, but couldnt find the exposed portion of that wire. after i changed out the ecm, i must have moved the wire some because it hasnt happened since, but i'm not foolish enough to think the problem went away on its own. will i be certain to get that replaced when i do the underhood wires, or is it possible its shorting up under the dash?

1meanGTA

what am i going to need to take to the salvage yard with me to pull out the harnesses under the hood? just my usual set of standard + metric ratcheting wrenches, socket set, nut driver + allens, couple sets of pliers will be plenty, right?

radical82

Also add some good side cutters to cut all the clips, etc that hold the wires in place... I always replace the wire holders with some new ones, I prefer using either rubber insulated Adel clamps or the good plastic ones. I also use a lot of shrink sleeve and tie wraps putting things together...makes for a neater job and protects the wires from damage.

Drew

iTrader: (58)

To remove an engine harness, start at the passengers side in the interior. Disconnect the engine harness from the dash harness up next to the heater box, then from the ECM. The bulkhead connector is a [ type clip, just slide it up and slide the plugs and harness through the hole into the inner fender well. Remove the fender liner, and snake the harness up past the frame rail into the engine compartment. Take your time, don't force it. It has to be lined up just right to fit through the hole. Work your way down the harness from the passengers side of the firewall, all the way over to the drivers side. Eventually it'll go back to the firewall at the C100 connector. You'll have a large plug with two bundles, one is the engine harness, the other is the headlight harness. Between them you'll find a single bolt that holds the connector together. Remove that bolt and slowly rock the connector loose. Once loose you can seperate the engine harness from the headlight harness. Keep in mind the harness is anchored to the top two bolts on the bell housing. You can either remove the bolts, or unclip the anchors with a flat blade. There might be a couple more of those anchors depending on the year. There will be connections to the starter. The harness will also go down to the transmission, there will be two plugs down there. The rest you should be able to get at from the top of the car. As long as you're at it, you might as well grab the battery cables too, they'll basically be hanging loose at that point anyway.

The fuel pump wiring goes into that C100 connector, goes through the dash harness and back to the floor between the back seats. You should be able to trace the route in your service manual and locate the fault.

1meanGTA

surprised to see someone from salina post, i grew up there, still visit a lot.

littletimmy9

hi read your post on painless wiring and would like to know with one you used i am planing a rewire to and have done called painless he told me one he said mit work would just like to know what you used thanks

radical82

I used the Universal with the GM steering column connector....Takes time to do it right, along with a thorough understanding of 12V electrical systems....