Overcharging, no start, and weak idle

[Tob]

I need some help with a diagnosis!

For a few days this week, I got the “Check Gauges” dash light alerting me to high battery voltage while driving. About once every trip, the battery voltage would rise and fall, fluctuating from normal to high voltage, triggering the “Check Gauges”. This morning, the Jeep would crank but not start (no combustion happening).

• I checked all the important fuses and found none blown.
• I attempted a jumpstart, did not work.
• The fuel pump runs at the ignition “ON”

This afternoon, I successfully started the Jeep with starting fluid to the throttle body. At first it had a weak, low idle that required throttle input to keep it running, but then it held idle after a few moments. After a short test drive, it still had a weak, low idle but did not die without throttle input. I turned it off and was able to start it again without the help of starting fluid, but it still has the low idle.

My main suspicion right now is that some sensor or other electrical component was damaged from high voltage during the last bout of overcharging. Any insight on diagnosing the issue is greatly appreciated! - both towards the overcharging and the weak idle / no start issue.

 

[Link]

The two issues may be unrelated.

Check all your grounds. Clean and brush them really well. All your grounds not just the battery. The voltage regulator is inside the PCM so hopefully that’s not the issue. It could be though so check with Wranglerfix.

May have a fuel pressure issue so I’d want to test that too.

 

[Tob]

Well, I hate to conclude this thread without a resolution, but the issues above mysteriously disappeared overnight!

 

[macleanflood]

Maybe water in some of the sealed connectors and temperature is affecting it? All wild guesses.

-Mac

 

[Link]

I’d still be running some tests. Check the battery voltage with the engine off and the engine running. I’d also still clean all grounds