Mattyice77

Hey everyone, got the classic no charge issue with a new battery/alternator that passes bench test (tested it like 6 times at different auto stores). Where is the internal voltage regulator at? I’ve seen some people say it’s in the PCM and I’ve also heard that it’s just in the alternator. Which one is it?

Ralph77

Would like to know how you know it is not charging?
Cluster telling you so?
I want to say the PCM but regardless 3 things come to mind.
The alternator is experiencing thermal failure.
The fusible link is messed up.
That you need to check all connections to the alternator and battery plus all the grounds.

Saudade

From the '99 FSM:

"DESCRIPTION
The Electronic Voltage Regulator (EVR) is not a separate component. It is actually a voltage regulating circuit located within the Powertrain Control Module (PCM). The EVR is not serviced separately. If replacement is necessary, the PCM must be replaced"

Is your CEL on? Are you getting any codes?

Mattyice77

[QUOTE=Saudade;3687629]From the '99 FSM:

"DESCRIPTION
The Electronic Voltage Regulator (EVR) is not a separate component. It is actually a voltage regulating circuit located within the Powertrain Control Module (PCM). The EVR is not serviced separately. If replacement is necessary, the PCM must be replaced"

Is your CEL on? Are you getting any codes?



Word thanks. no cel. It will intermittently not charge the battery. First time it did this was a month ago. After cleaning all grounds/putting on new terminals it was running fine. Fast forward to yesterday I drive home from work all normal and when I went to leave later it wouldn’t charge the battery upon starting. So this morning i cranked it and all was well. Then voltage started dropping again after a 30min drive.

Mattyice77

yeah cluster will either say “check gauges” with the volts pinned at 0. Or it’ll run fine for a time and then randomly volts start dropping. Although it’s never completely died on me. First did this a month ago and after cleaning all grounds and replacing terminals it ran good till this morning.

Ralph77

Kinda leaning towards thermal failure.
Had that happen with an alternator I had my guy rebuild and up the amps in.
How did you have it tested when you did?

Saudade

Also, did you have the "no charge" before the battery/alternator replacement?

Mattyice77

Oreileys/auto one/Napa did the amperage test they do when you bring one in. The one o’reileys tested it 4 times in a row and it was showing healthy readings even into the 14.5 volt range.

Mattyice77

yeah, as soon as it started happening as I was driving I pulled into the nearest store and got the new battery.

Ralph77

Should have been more specific in my question.
In or out of the Jeep?
If in working properly according to the cluster gauge when tested?

Mattyice77

oh my bad. I removed it from the jeep. And they hooked it up to their tester. Since I automatically thought it would be bad

Ralph77

I kinda thought that is how you would say you had it done.
Still kinda leaning towards my thermal failure theory.
If this were me I would either defect it or put it back in, drive around, wait for it to **** the bed, and go right to an auto parts store and have it tested.

Mattyice77

Update: Started jeep after topping battery back off and connected multimeter to battery negative and alternator output lead. Getting 12.35 initially and dropping to 12.32-12.34v at alternator and battery after 1 minute that’s low right?

Ralph77

Maybe not.
Thinking some of it depends on how cold it is where you are.
You did say you topped off the battery also.
The drop could be cause the idle will be higher at startup and drop as she warms.
Usually happens quickly.
Try putting a load on it.
Turn everything on.
Rear defogger will draw a lot of juice.
Push in the cigarette light too.
See what happens.

Mattyice77

with the rear defogger on and all lights running it dropped into the 11v range and kept slowly falling. Once I turned them off it jumped back to 12v. The jeep has been in a heated shop all day