Intermittent problem: dash lights work, gauges do not / when this happens it doesn't run

c670809

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Let me first say, Thank you for your help. I appreciate it very much.

My 16-year-old daughter has a 2004 Jeep Wrangler X, automatic, 4.0. We're having a problem that we're having a very hard time tracking down.

Symptoms:
Intermittent, might drive 1 mile or 50 before problems
If running it will die - no hesitation, just die
Sometimes it will immediately restart, sometimes not
When it doesn't restart, with the key on the dash lights are on but the gauges do not work. It will crank but not start.
Generally, after sitting for anywhere from 30 seconds to 10 minutes it will restart. It might act up again in 10 seconds or 30 minutes.

When it is acting up, if the key is turned on the dash lights work but the gauges do not. When it is not acting up the dash lights and gauges both work.

I am at a loss. I would normally take it to my mechanic but it's hard to diagnose a problem that doesn't happen all the time. I drove it for 50 miles today before it started having problems.

I tried searching the forum and didn't come up with anything. However, I may be missing something. If you would point me in the right direction, I would appreciate the help.

Thank you,

Matt Hayes
Reno, NV
 
Last edited:

Succentor

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Ignition switch? I had various random electricals working or not working and that proved to be the problem. Can you temporarily fix it by turning the key five or six times before starting?
 

CharlesHS

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Check the (3) PCM harness connector pins for oxidation and firmly reseat the connector into the PCM receptacle.
Check the split wire loom sensor harness that runs along the firewall and the rear of the valve cover then is routed near the threaded head stud (right rear corner). The threaded head stud is known to rub thru the split wire loom and wiring insulation which causes the wiring to short to ground.
These problems will cause the PCM signals to be interrupted shutting down the engine and interrupting the signal to the gauges.
 
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hear

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Ignition switch? I had various random electricals working or not working and that proved to be the problem. Can you temporarily fix it by turning the key five or six times before starting?

I was thinking either this or SKIM-related.
 

hear

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The SKIM will not interrupt the function of the gauges....
IF the Ignition switch were involved; I would expect other electronics to also be affected.

You're 100% right.


When it is acting up, if the key is turned on the dash lights work but the gauges do not. When it is not acting up the dash lights and gauges both work.

This sounds canbus related, since gauges are run by it and lights aren't. Definitely do what Charles suggested in post #3.

And just for good measure check the fuses in the glovebox, that they're all the right size for the circuit they're on and no melting or anything. I'm certain that's not your issue, but I had some complicated wiring issues and I wish I had recognized the PO had put a 20A in a 10A slot, would've saved me a TON of work.
 

97JadeTJ

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These sound like the symptoms my 97 2.5L showed after the PCM got wet… I was able to figure it out by checking for 5 volts at pin 17 of the PCM when it wouldn’t start… pin 17 supplies 5 volts to 5 different sensors in the vehicle which are required for the vehicle to start… no 5 volts not start!… A new to me PCM solved the problem…
 
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c670809

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I thought I would check in and update everyone.

txbemis69 appears to have been right. We pulled every connection we could find apart and up dielectric grease on them. We also cleaned the ground and made sure the computers were grounded. So far, so good. No problems since all of that.

Thanks again for the input and help everyone, I appreciate it.

Matt
 

txbemis69

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I thought I would check in and update everyone.

txbemis69 appears to have been right. We pulled every connection we could find apart and up dielectric grease on them. We also cleaned the ground and made sure the computers were grounded. So far, so good. No problems since all of that.

Thanks again for the input and help everyone, I appreciate it.

Matt

well that was a lucky guess. glad you got it sorted out.