Need help please, my 98 Cherokee suddenly stopped charging. Alternator was bench tested at oriellys and it is working fine. Optima battery tested fine after being charged. I discovered that the voltage regulator is in the ECU. Any Ideas please.

 

It is my understanding Renix era voltage regulator is in the alternator, someone correct me if I'm wrong. I would suspect a bad connection or wire in the charging circuit somewhere.

The ol Cruiser's ground tips might be in order.

 

check batt terminals, clean and redo. measure volts at batt. should be 14 +-.

 

I think the voltage regulator is in the alternator as well on Renix era XJs. Also....be aware that bench testing of alternators is not without it's issues; there can be "escapes" (alternators that bench test good at the parts store but are NOT good).

Start with Cruiser's tips 1-5. Grounds are notorious for being an issue on these Jeeps. Cruiser knows his Renix Jeeps. (Cruiser....how am I doing here? )

Make this link a bookmark.

http://cruiser54.com/

 

Great job Tom!!! LOL.

Yes, indeed the voltage regulator is in the alternator. There's an easy test if the OP is interested.

 

Edit, Whoops! I read "89" ? Did you change that? (big differences)

Cobra, you might check the yellow trigger wire at the alternator plug for power with the ignition on.

TJ-0P.......89-90 don't need the appropriately named #2, no C-101 connector.
(Just on 87-88)

 

Thanks for the posts, Yesterday I checked and rechecked all of the grounds with my power probe, put a different battery in to eliminate that. Checked power at back of alternator and at the power dist terminal on the post which only came up to 12.1 with lights, radio and ac on, but gauge went all the way down to 9. At one point the gauge did come back up to 14 and the alternator was making a different noise like it was working so I took off down the street and the gauge went back down to 9. Also swiched out the ASD relay with another good one. Plan today is to take the alternator back to the parts store and check again. I just didn't want to buy an alternator if it wasn't the problem. I heard that some of the Chrysler voltage regulators were in the pcm? My jeep is a 98 4.0 with automatic overdrive and a 242 tx case, trans is a 30-43LE dana 30 front, Chrysler rear. Limited Edition with leather one owner before me with 155,000. bought in Cali and drove back to Oklahoma. very clean with a stack of service records. Now has a Rusties 4.5 lift, 33 inch tires, roof rack, k/n, JBA header and SCT tuner. Sorry I'm dyslexic my jeep is a 98 not 89

 

91 and later. Yours is in the alternator.

 

Next step: Go back and check them again, properly. If you didn't take them apart, you don't know if they are good.

See my sig, #1.

 

Yup^^.

 

the alt is grounded when you bolt it in. if you read output volts on the alt cable it should read apx 14. if input volts are ok ,not much left.

 

Thanks everyone, I had already done everything you guys mentioned before I posted this. Thought there might be something I didn't know about Jeeps. Turns out it was the alternator. Had mine bench tested several times ? and it always passed. Thanks again

 

You completed Tip 1 at www.cruiser54.com?

 

My XJ does not have a ground at the dipstick, it has a ground strap attached to the back of the head. Thanks I will explore your site some more.

 

if the car starts the heavy connections are good. if alt has normal field control volts and the output is low it points to the alt which is solidly bolted to ground.
even with a weak batt. ive had cars start that barely turned over. alt volts came up normal.