Recently purchased a 92 xj grocery getter. Jeep is in overall solid shape, been sitting about a year, put new battery in, started right up. Charge at idle was, about 11.7, but would jump to 14 at 2k rpms, verified by gage and multi meter at battery. Started like this a few times, then it stopped moving off 11.7. I replaced the alternator, cleaned all grounds, and the new, known good alternator behaved the same way, low at idle, and 14 volts at 2 k. Drove around the block, pulled in driveway, now the new alternator is doing the same thing, will not move when revved up. 'Checked all underhood fuses are fine, Im not getting any sign of voltage, at the alternator B post when it is running as verified by test light. Is this the sign of a failed voltage regulator, and will the ammeter on the dash still function if I hook up an external voltage regulator.

 

IIRC the 93 and up charging is controlled by the ECM module. It will need to be replaced. A common XJ problem

 

Looking at my 93 FSM, pin B (dk green with orange stripe wire) should have +12-volts on it with the key-on. It gets fed from the ASD relay along with the injectors and ignition coil. Pin C (dk green wire) goes to the ping 20 on the PCM which controls the ground side of the field coil.

 

Yes you can place a aftermarket voltage regulator on the vehicle. Obviously some things will not work the same but the battery will then charge properly.

Here's a google video... not mine but gets the point across.

 

I have a 1992 cherokee. I have looked online and found a voltage regulator but have no clue where it would go, assuming in the alternator. Does anyone know for sure that 92 is in the ecm or alternator?

 

Yes, it is controlled by the ecm. If it's the ecm, it wouldn't be intermittent. See my previous post. Test with a meter or test light before you start cutting up the wiring. The new alt might be bad, belt slipping, or damaged wiring. Is the.check engine light on? It will be after you bypass the ecm with an external regulator.

 

I believe there is also a green fusible link near the pdc hat needs checked.

 

I read that fusible links were replaced by the underhood pdc? There was no voltage present anywhere with the key on. So youre saying there’s a fusible link to protect the fuses?

 

In the early XJs there was. But that changed when Chrysler took over. All fusible links are located at the starter solenoid on the right fender wall

 

I know i have a 92 bro solenoid is on the starter. I was questioning the fact that there is a fusible link to protect the pdc? Seems odd

 

Not sure how applicable, but here goes.
1996 Cherokee XJ, 367,000 miles. 4.0L i6, manual.

Last year iirc I was having charging trouble. No checks with the alternator on the vehicle produced any solid diagnosis.

Installed external regulator, all it did was overcharge (didn't use and adjustable one).

Finally broke down and ordered a new one with lifetime warranty from Advance. When I wrestled the old one out and gave it to the clerk for core, he checked it on their test stand and said it failed everything.

So, there you go.

New one is working fine.

 

The fusible link, if there is one (not sure on the 92), would be on the output of the alternator to the PDC and probably not intermittent if it melted. The voltage for the field coil in the alternator comes from the same circuit that provides voltage to the coil and injectors. You might need to check with key-on and engine running. If you're not seeing that voltage at the alternator, then the main problem isn't the alternator or the ECM not providing the ground to energize the alternator.

 

I have 3 x '96 and have had alternators fail a few times, after putting a rebuild kit in them, they still didnt work.

I purchased 3 of a guy that was wrecking '96 ers and that has got me out of trouble, also bought the PCM, sensors and fuel pumps off him