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Old 03-11-2013, 08:31 AM
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Wiring Issue

Ok so I have gone threw the threads on wiring issues and it seems i have something not addressed before.

I have several wires that come from the firewall toward the front of the engine and attache to several sensors on the exhaust and carburetor and other sensors. they were not run correctly and were laying against the valve cover and on top of the exhaust manifold between the carb and the valve cover. They have all become brittle and basically disintegrated in my hand when i moved them out of the way to get the carb to look at something.

Now at least one of them goes to the electric choke not sure if it is a warm weather choke or cold weather choke. I have the Chiltons manual and it does not do a great job of describing this item. However it is adequate.

The other sensors I can only assume are EGR related or Oxygen sensors?

Any body have an idea on where they go and which wires go to which and how to trace them when basically about 3 inches of them are gone I tried tagging the ones that were not completely dissolved so I am moderately confident on about half of them. But some of them just completely were wasted they had been overheated for some time.

Last little tidbit is the jeep used to start although it ran rough it did start now it does not crank. Seems like this wiring is the culprit but not sure.

I tested the solenoid by touching a wire from the Positive side to the small wire and it did not crank but you heard a loud pop like the starter was trying to kick over.

Sorry for the long post
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Old 03-11-2013, 12:10 PM   #2
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Couple of things to help us out would be to completely fill out your profile with engine type and mods done. I assume you have an '89 4.2 with the BBD carb. If so, research the Nutter Bypass here and you can eliminate the stuff on the exhaust manifold. The choke is good to have as well as the manifold heater circuit. Other sensors there are all for the ECU basically and if you Nutter it, they can be eliminated. This will also depend on where you live and the EPA constraints. The Nutter doesnt hurt you with the tail pipe sniffer test but the visual part if the place knows what to look for. Most of the time folks put an aftermarket carb on and the lack of OEM air boxes alerts them to changes.

Your gauges are controlled by other sensors so they are fine. The ones on the manifold tell the ECU how to control fuel mixes and sets the timing for cleanest emissions.

There is a knock sensor, a temp sensor and a vacuum manifold port switch if memory serves. If you need wire colors, I will look at the FSM later for you.

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Old 03-11-2013, 01:45 PM
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wiring issue

Yes color codes would be good I pulled back the plastic surround to expose the wires and I can now see the different colors of each wire. One is spliced not by me so that concerns me.

In addition I have replaced the battery cables and checked the battery to starter relay wire it is solid and securely fastened. I put a volt meter on the solenoid attached to the starter and I get 4v from the battery to the small wire. When I check the battery by itself I get from 10 to 12v depending on how hard I hold the contacts. So should I replace the solenoid. Also when I jump across the battery lead to the small wire lead on the solenoid it clicks but does not try to start the engine.

So it seems like a short but just not sure where and all those wires you described should not keep the vehicle from turning over in my opinion unless I am missing something? If I am wrong please correct me.


By the way I updated the profile. It is a 88 YJ with a 4.2 L Carb'ed engine with a Manual Peugot transmission NP231 transfer and 3 inches of lift.

No mods installed by me. Previous owner who the heck knows.
Lastly the vehicle did crank right up when I installed the new battery last week.

Again sorry if the post is overly long
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Old 03-12-2013, 07:43 AM
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Wiring Issue

Ok guys I think I have it figured out.
The alternator was bad and was not re-charging the battery so the new battery was completely dead took it back got it re-charged and bought a new alternator.

Will install them today and see how she runs.

Word to the wise when you hear a loud noise from the engine compartment do not dismiss it as a belt issue could be your alternator.

Yes I am a dumb dumb
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