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I've had off and on, nagging electrical gremlins for the better part of 2 years now. And it's aggravating.
My harness is not in great shape so I'm thinking of doing an aftermarket replacement. Speartech, Painless, BP, and PSI all offer harnesses. All pretty similar in price.
I've had off and on, nagging electrical gremlins for the better part of 2 years now. And it's aggravating.
My harness is not in great shape so I'm thinking of doing an aftermarket replacement. Speartech, Painless, BP, and PSI all offer harnesses. All pretty similar in price.
Anybody have experience with them?
The one thing I've been afraid of about them is they advertise their products as "Stand Alone" harness and I am scared that it might not integrate properly with the rest of the car. Meaning, I don't know if all your gauges will work, your OBDII port, and so forth. I know the lights, alarm, and other stuff has nothing to do with the engine harness so would a stand alone harness readily swap into an F-Body?
I'm also very interested in this, when I pull my motor for a rebuild I want to address my wiring as well.
The engine harness is very easy to pull, it basically snakes around the motor down the drivers side of the rails down to the alternator, and from behind the intake back down to the transmission.
I think it took me a total of 30 minutes to do it. I don't think it would cause any electrical gremlins, you've probably got another issue you will find when you pull the old harness out to inspect it
It's a short somewhere between the TPS and the ABS. I pulled the ABS and that fixed it. I would randomly see TPS values that would jump up .2V for no reason. And it wasn't TPS related since I tried 4 of them.
But now it's back. The ABS pull fixed it for about a year. But it will randomly do it and then settle back in. The issue is, when it jumps up to .79V or so at idle, it pulls it out of the idle routines. Which is okay. My car can idle fine without the nannies to help it when adaptive spark goes out. But it shouldn't be doing that. When I check it, it doesn't give me 5V at the TPS... it's usually 6V on the reference wire. Doing a TPS relearn doesn't do anything. Randomly, it's settle back in to .59V which is where my TB is set. And then if I pulled the TPS and check the wiring connector, it's a 5V again. So, I don't know why it jumps up to 6V reference.
Tracking the schematics, I found the ABS was on the same circuit. And when I pulled the ABS, that fixed it. Until yesterday.
So, I'm willing to try a new harness. Since my harness looks like it's seen better days anyway.
Ya I've seen the harnesses advertised as 99-02 ls1 harness but I don't think they are actually direct swaps into our cars. I'm sure they can make them that way though. I would just call painless or speartech and ask. One of these days I'd like to redo mine as well, it's seen better days.
Speartech does a harness "redo" of sorts that's the cheapest of any. I'll call and see what they recommend.
Of course, it'd be nice to keep my old harness in case there's an issue with the new one. And having mine hacked up puts me at the mercy of an aftermarket harness.
might be a bit off but have you tried possibly swapping ECM's with another known good one? Only reason i think it could be a problem is that obviously controls reference voltage, and you said when the issue acts up you see 6 volts instead of the 5 volts you're supposed to have. Maybe something inside the ECM is getting a little screwy, I'd think if you were having a short issue you'd see closer to battery voltage.
And, I may be wrong, but the TPS and MAF and IAC are on different reference 5V circuits per the schematics I've looked at. However, the ECT is on it with the TPS, and it goes screwy too when the TPS goes screwy. Like it'll jump from 190 to 208 for no reason. And again, it's because the reference voltage is off and pushing everything "up."
But it may be the PCM. It'll be cheaper to try a new one vs a new harness.
I disagree. It's not hard to make a nice and quality harness and there are a few company's that do. It's the fly by night companies that do **** work. With all the proper wire colors and pins, crimpers, and loom , you could make your own harness exactly how you want it. That's the route Ill probably go at some point.
Here in Pasadena tx you can buy 99+ silverado engine harnesses brand new at a dealership for 250. I haven't asked if they have any fbody ones, but doesn't hurt to.
I disagree. It's not hard to make a nice and quality harness and there are a few company's that do. It's the fly by night companies that do **** work. With all the proper wire colors and pins, crimpers, and loom , you could make your own harness exactly how you want it. That's the route Ill probably go at some point.
What company makes a high quality harness?
I'm sure someone could purposely set out with a goal to make a better wiring harness, but nobody makes an aftermarket one that compares to a GM harness. And to make one yourself would cost a lot......
GM harnesses can last 50 years easily. The aftermarket harnesses I've heard about are nowhere near the quality of GM.
I want to buy one, just to have a spare. Or find a good one in a junkyard.
What makes a Painless, SPI, Classic auto wire, etc no where near the quality of a GM harness?
Millions of $$$ of automated equipment. Millions of $$$ and thousands of hours of testing and development. The best quality wires available. Tested on the actual car that its supposed to be used for. Expensive accelerated age testing, heat testing, cold testing, water testing, etc.
I've seen aftermarket harnesses, they feel half the weight of a GM harness and held together by Home Depot zip ties.
The best aftermarket harness I ever saw in person was $650.00. Can't remember the name brand, but its from the same people that make the dual tune PCMs. It was nice, but it was nowhere near as heavy duty as the GM harness.
Thats why I'm going to look for a junkyard car.......
07-12-2017, 04:53 PM
Want to do a New Engine Harness 
