98 XJ Check Gauges, Low Voltage
 

I have a 98 cherokee and recently the battery gauge dropped to 9v and the check gauges light went on. I have currently done the following with no results:

Battery was tested at the auto store and is good
Alternator was tested at the auto store and is good
Purchased a refurbished engine control computer from flagship one inc. (i thought the internal voltage regulator may be bad), no difference
Earlier this year i replaced the battery cables, same ones from the kelleyswip list

1. (+) to Starter Motor
2. (+) to fuse box/PDC
3. (-) to Engine Block
4. (-) to Fender
5. Braided cable from rear of Engine Block to Firewall

Its not just the gauges on the instrument cluster because the car did eventually die. When i had the car idling and checked the battery with the multi meter it was reading around 9v, then i would turn the lights on or the heat on and it would drop. Also while driving the stereo would turn off and the abs lights would come on finally it (luckliy) died in my driveway coming home.

I read on this forum that the distributor and rotor could be an issue but i am not sure why that would be the case. Does anyone have any other ideas. I have gone back to check the ground cables that i previously installed and they all look good, no corrosion and tight connections. My thoughts are that it is still a grounding issue i am just not sure where to look.

Thanks,
Josh

Im experiencing a problem very similar to yours. Did you ever find a solution?

I would double check your alternator and do a parasitic draw test on your electrical. Plenty of youtube videos on how to check your charging system and how to check for a parasitic. Chrisfix does a great job on his videos.

Thanks for the reply! I actually did a drop test today and it didn't reveal any problems. My XJ is showing 11.5v when the engine is off and 12v when the engine is on. As of now, what I know is:

*The battery is new
* I removed the alternator and had it tested at 2 different Advance shops - both times it passed
* I replaced the battery posts and both battery ground cables. (The positive cables seem ok)
* I removed and cleaned all the grounds (2 on engine, the strip by the firewall and the two small ones under the ECU)

One important note is that this problem occurred at the same time that I had a problem with my Crankshaft Position Sensor. I've replaced the sensor and now that problem seems resolved (first with one from Advance that didn't work and then a Mopar from Rockauto). Perhaps this low voltage problem and the CPS sensor are related?

Turns out the alternator was bad. Apparently there are times when it can test fine on the bench machine the auto stores uses even though it is faulty. I replaced the alternator and everything was working as it should.

Thanks for the response. Today, I took the alternator apart to look at the voltage regulator and one of the brushes that rubs on the commutator bar was really worn down. So, I brought it back to the parts store and they agreed to honor the warranty and gave me a new one. Everything seems to be working fine now (fingers crossed)!!

I had that alternator tested at THREE different parts stores and it passed every time.. Those machines obviously are limited in their ability to diagnose properly.