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91 z28, P.O. was a crack head, help me fix a wireing mess

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Old 12-06-2016, 09:47 PM
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91 z28, P.O. was a crack head, help me fix a wireing mess

Ok guys/gals. I'm assuming the meth was good one night and the last owner of my car thought it was time to redo the wiring. Needless to say it'll never rock a tpi again.

So now I'm trying to get the car up and going on the wires needed to run just the simple things.

What works.
Headlights, blinkers, running lights, tail lights, brake lights, high and low beams, oil psi, volt, temp gauges clutch safety switch, reverse lights, dome, gauge lights, and suprisingly the cigarette lighter.

What dont, gas gauge pegged on full, fuel pump wireing shot, no speedo, ecm missing, all the wires to the ecm are laying on the finder.

For temporary use I have a GPS unit for speedo and bought an aftermarket 0-90 omes gas gauge.

New gas gauge reads 1/2 tank even tho tank is full.
But the big kicker is when you turn the key on the headlights come on and the door buzzer won't shut off, and that makes the gas gauge spike to past full.

What I've done.
I put a temporary toggel to a relay to run the fans, wired correctly.
Wired a hot switch (with fuse) to power fuel pump. Installed carb.

So what I need is help finding out what I need to cut out because I'm going 5.3 ls later on down the road.

Also need to find out why the headlights pop on and gas gauge jumps, and maybe finding those issues will help fix the speedo.
Has new fuel pump, new sending unit, and new tank.
Old 12-07-2016, 12:08 AM
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Re: 91 z28, P.O. was a crack head, help me fix a wireing mess

If they unplugged the C207 connector near the ECM then you could be missing a ground that is necessary for some things. I think it is the ground for the VATS, Datalink, and whatever else is on that common ground. Just something to consider looking at. I know it won't solve all your problems but maybe pick away at something to make a bit of progress.
Old 12-07-2016, 09:33 AM
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Re: 91 z28, P.O. was a crack head, help me fix a wireing mess

Get a chilton or something with a wiring diagram. Definitely try and trace down what needs grounds.
Old 12-07-2016, 01:20 PM
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Re: 91 z28, P.O. was a crack head, help me fix a wireing mess

I have a book, and alldata . But I'm not the best at schematics.

I'll try to find the c207 plug, and look for the grounds there.
Old 12-07-2016, 08:10 PM
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Re: 91 z28, P.O. was a crack head, help me fix a wireing mess

Originally Posted by 91Z28_Nightmaro
But I'm not the best at schematics.
On the bright side, you'll be a lot better at it before this is done.
Old 12-07-2016, 10:52 PM
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Re: 91 z28, P.O. was a crack head, help me fix a wireing mess

Originally Posted by 91Z28_Nightmaro
I have a book, and alldata . But I'm not the best at schematics.

I'll try to find the c207 plug, and look for the grounds there.
The factory service manuals (electrical diagnosis supplement in particular) would be invaluable in cases like this.

See attachments for examples.
Attached Files
File Type: pdf
Sample 1.pdf (97.8 KB, 58 views)
File Type: pdf
Sample 2.pdf (227.6 KB, 64 views)
File Type: pdf
Sample 3.pdf (153.1 KB, 60 views)
File Type: pdf
Sample 4.pdf (276.7 KB, 62 views)
Old 12-18-2016, 12:22 PM
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Re: 91 z28, P.O. was a crack head, help me fix a wireing mess

Yeah I've still had no luck. I've found a few more lose grounds and other cut wires here n there. But I've made headway




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