CanuckXJ

I am thinking my alternator might be biting the big one, when I start my 93 it appears to be running on battery power (dash gauge sits on low end of the gauge) and the check engine light is on. After a short period of time (1-5 mins) it's almost like the alternator kicks in and everything is fine. If I turn my Jeep off and on again immediately the check engine light goes out and all appears fine but if I shut it off for any period of time the whole process starts again.

I have read about everything from battery temp sensors to PCM failure... Any insight would be great.

tjwalker

As you have had a check engine light, you should have stored codes waiting for you within your computer. Pull the code and that will help guide you, but I'm guessing that your alternator is heading south.

Common failure code for an XJ alternator is code 41. Here's how to easily pull stored codes. This is not a battery temp sensor or PCM problem.

Good luck and post back what you find!
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Retrieving OBD codes on the Jeep Cherokee (XJ) OBD1 Models: 1991-1995

1) Start engine (if possible). Move transmission shift lever
through all positions, ending in Park. Turn A/C switch on and then off
(if equipped).
2) Turn engine off. Without starting engine again, turn
ignition on, off, on, off and on within 5 seconds. Record 2-digit
fault codes as displayed by flashing MIL.
3) For example, fault code 23 is displayed as flash, flash,
4-second pause, flash, flash, flash. After a slightly longer pause,
other codes stored are displayed in numerical order. When MIL begins
to flash fault codes, it cannot be stopped. Start over if count is
lost.

NOTE: A "5-5" will always occur to signal the end of the sequence. Some will flash the "1-2" code indicating a recent battery disconnect even if you haven't done it. Ignore these two codes, and mark down all others.

1991Jeep_Man

Sound advice. Follow it. I had the SAME exact symptoms you described on my 91. Alternator was dead. Replace, be happy, drink beer!

CanuckXJ

Thanks for the information, I will do this in the morning. Given that I have a 5 speed I am going to assume that I would skip moving the shift lever through all the positions?

tjwalker

Yup, the same basic procedure would apply and I've seen where it does work for pulling codes.

bryanintowson

If you do have a failed alternator, replacing mine on my 92 was a major pain in the rear. I would suggest having it done at a shop to save yourself the headache if it's configured like my 92.