Early 97 TJ Check Gauge Light (but went away) - Hard to Start - Voltage at 12V

PattonD

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The daughter was driving our early 97 TJ, and the check gauge light came on; she looked and could not see why. When I went to start it, it took much longer than normal to start, and I saw the voltage gauge wasn't up to 14v per usual. The check gauge light did not come back on.

I was assuming I had an alternator issue, but I am seeing a few posts saying hard start plus not charging means it's the computers; what is my diagnostics process? I am confused between PCM and ECM, does it have one unit serving both functions? Is there a rebuilder that is better than the others? Is anything here one of the unique early 97 issues?

Thanks,
Patton
 
Your Jeep has a Powertrain Control Module, PCM.

The voltage regulator is in the PCM. I would have the alternator and battery tested first as auto parts stores will check that for free. Also, check the battery cables for corrosion and clean up the battery posts and connectors and the grounds.

If it turns out the regulator is bad, there are external ones that can be installed so that you don't have to replace the PCM.

If it turns out you need a PCM, Wrangler fix seems to be the way go.
 
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My battery charge has an alternator test, but how does it know if it is the alternator or voltage regulator in the PCM?

Due to the the sudden hard starting and the charging issue starting right after the check gauges light flashed on, I want to make sure the PCM is OK before throwing an alternator on it just to see.