96 ZJ Wiring Harness help!

6310 Views 9 Replies 5 Participants Last post by kjablonski, Oct 14, 2011

kjablonski

Discussion Starter · Sep 26, 2011

First off let me say thanks for all the help i have gotten over the years for my jeep.

Symptoms:
Unreliable starting. Sometimes it will start right up and others i can sit there and crank it all day and nothing will happen. Sometimes it does it when its hot (100+) sometimes when its cooler (~75)

I have had:
The ECU problem (which this forum helped diagnose)
Cracked Ignition coil (replaced)
Crankshaft Posision sensor (replaced)
Distributor (replaced)
sparkplugs and wires (replaced)

and now my mechanic is telling me that there is a short in the wiring harness and to fix it we will need to replace the whole thing. I can't find any information about how much a part will cost and then how to replace it. I prefer to to the work myself, but just out of college my tool selection is greatly limited.

How much is a wiring harness for a 96 ZJ? where do i find one? How long and hard to replace it?

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ZeeJay1997

· #2 · Sep 26, 2011

It's very unlikely you need a wiring harness. If you do need a harness, it will have to come from a salvage yard. I would make the mechanic tell me why exactly I need a wiring harness.

Are you missing spark or fuel? If you have both and it doesnt crank, given the things you have replaced, I would look very carefully at the cam sensor and connector. The connector has given me problems where it didnt want to crank until i unplugged it and plugged back in. Then I used a sharp point to elongate the sockets so they would hold the pins better. No problems since.

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kjablonski

Discussion Starter · #3 · Sep 27, 2011 (Edited)

They traced it to a short in the wiring harness and suggested that i replace it because the wires are most likely brittle and breaking. I think i can just splice the short with new wire?

It cranks, and gets fuel. Mechanic replaced cam sensor.

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RJSoAZ

· #4 · Sep 27, 2011

kjablonski said:
I think i can just splice the short with new wire?

I'm going to say yes... My wiring harness had an unfortunate run in with a sawzall, I spliced about 12 wires back together and i havent noticed any ill effects yet.

If you want to be completely anal about it, I would imagine, depending on which wire(s) are the culprit, that you could replace the entire wire pin to pin, with enough patience, of course this becomes less practical as the number of wires increase

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kjablonski

Discussion Starter · #5 · Sep 27, 2011

RJSoAZ said:
I spliced about 12 wires back together and i havent noticed any ill effects yet.

How did you insulate your splices, electrical tape? I was thinking heat shrink tubing but that might be overboard.

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RJSoAZ

· #6 · Sep 27, 2011

kjablonski said:
How did you insulate your splices, electrical tape? I was thinking heat shrink tubing but that might be overboard.

My buddy had that liquid electrical tape, then I rewrapped the bundle in actual electric tape.

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kjablonski

Discussion Starter · #7 · Sep 29, 2011

UPDATE:
So my new mechanic I took my car to has identified the problem. Not a short so i will update the thread title. When I took it in to my ususal mechanic and had the cat replaced, they put an new one in that was too small. This increased the backpressure on my cylinders and was preventing it from starting and causing it to die while running. The mechanic bypassed the cat (for diagnositc purposes, removing or tampering with any part of the emissions control is illegal and not condoned by this forum) and she fired up right away and ran like new!

Parts replaced so far with this problem:
CKS
Distributor cap
Distributor rotor
Distributor
Cam Position sensor
cat x2
General Tune up (plugs and wires)

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JS97ZJ

· #8 · Sep 29, 2011

How old was the cat....milage?

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ratmonkey

· #9 · Sep 29, 2011

i find that very hard to believe. it'd have to be in the range of a 1" diameter in/out cat.

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kjablonski

Discussion Starter · #10 · Oct 14, 2011

I thought it was hard to belive as well untill i saw him try to start it infront of me, it would fail, he bypassed the cat, started right up.

Update:
At the end of everything what ended up being replaced was:
Cat (ill post pictures of the differences this weekend)
CKS
ECU (unrelated problem mechanic's fault no cost to me)

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