I have a random starting problems. I have a digital voltage regulator mounted in the dash and when I turn the key on it shows 10.3v. When it's starts goes slowly to 12v and finally gets to 13.8v.
it's running without problems until I get to home, shut it off it's shows 10.3v again. Yesterday left me stranded at work and it won't turn on. Slow crank and ticking. After trying a couple of times it turns and CEL went on code 41. I get home reading all the way 13.8v. This could be the alternator? Battery tested good. And the PCM was replaced 2 years ago. Recently I jump started a coworker a couple of weeks and this situation came up after this. Any suggestions are all welcome. Thanks

 

You need a new alternator.

 

I disagree on the core problem. You need a new battery. If you can, check the voltage at the battery with vehicle off. If 10.3, the battery needs to be replaced. Alternator does sound a little weak, but address that battery first

 

Battery tested good and its seems the alternator is charging I see 13.8v when running. But the code 41 got me puzzled. I'm afraid of having to remove and bench test the alternator and their gonna said is good and having the same problem again.

 

Well, not sure what to say then.

 

Well 4.3L XJ, you were right! The battery have a bad cell and a month away to expire the warranty. I upgraded to a Gold one.
and now I get 12.6v at the battery engine off. And it's start up right away!
I hope the alternator won't blew off too.
Thanks

 

Just to add up that is not the first time I deal with a not starting issue. I've replaced the alternator, starter and battery a couple of times but every time is a different symptom is hard to diagnosed it right.

 

Glad you got it sorted out. Good luck

 

I would also run new cables to the alternator and to the starter

 

I stand corrected in blaming the alternator. Cant win them all. Pulling alternators isnt much fun anyway.