TJ charging issue

snipes243

snipes243

Well-Known Member
Joined
Sep 18, 2007
Location
Huntersville, nc
So I have a 97 tj with a 2.5L and I’m having a charging issue. So I think the alternator is not being told to charge. I have checked the battery and the alternator at the parts store to make sure they are working, they are. The fusible link is intact. The grounds and cable are clean and in good order. But still no charge. The bits of information i have found on the web is the PCM turns the alternator on. Does anybody know how to test this without swapping PCMs?
 
snipes243 said:
So I have a 97 tj with a 2.5L and I’m having a charging issue. So I think the alternator is not being told to charge. I have checked the battery and the alternator at the parts store to make sure they are working, they are. The fusible link is intact. The grounds and cable are clean and in good order. But still no charge. The bits of information i have found on the web is the PCM turns the alternator on. Does anybody know how to test this without swapping PCMs?
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The alternator is regulated by the PCM. Check the wiring between the PCM and the alternator. If the wiring is good and the alternator is good, the PCM is probably bad. But I'd be 100% sure of the wiring, fuses, and the alternator before going down that route. If you have an external regulator laying around, you could always get the alternator running with that temporarily to confirm that's the issue.
 
Well I double checked all the wiring and grounds again, even got ballsy and replaced the alternator. Well still no charge, so I’m 90% sure it’s the pcm. So my questions has any one sent their pcm off to be rebuilt?
 
Check the two smaller wires on the back of the alternator for power across the two with the engine running. If not, probe the wires themselves. I've seen the connectors go bad internally. Not seen too many ecms fail though they can. You can get a salvage yard ecu and program your Vin number into it.
 
Check the little ground wire from the alternator to the block, most of the time bolted next to the dipstick tube, I've had that one bite me hard before.
 
I would bet the battery (which tested good) , would be more likely to be bad than the pcm
 
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