So, while driving around I had dead alternator symptoms, wipers nearly stopped, turn signals slowed down, etc.... Battery was still good. With a voltmeter at the battery terminals the voltage would be around 11.5 and drop with the engine revving. I replaced the alternator and while checking the the voltage at the batt terminal it still reads 11.5 with engine revving. Its a 1990 renix so the voltage reg is on the alternator I believe, so that should be ok right? Why isnt the voltage reading higher??

 

Did you replace the battery when you changed the alternator? If not have it checked, it may have a dead cell hindering charging.

 

I replaced the battery a week or so before I noticed the alt was bad. It was an old battery and wasnt charging completley with a charger or in the car itself. I replaced it only to find out that the alternator wasnt charging. Now with a new bat abd alt it still doesnt charge! When its daylight and the snow stops I need to check all wires in an out of the alt with the volt meter. Ive come to the conclusion that jeep engines will not die but everything connected to them does, especially at 217k miles!

 

does your battery gauge work?? CHECK YOUR CONNECTIONS!! I would bet you have a bad terminal or wire or connection... shouldnt be a big deal... worst case take the alternator back and tell them its not right...

 

x2

 

did you check the fuse?

 

No volt. reg. is in the ecu. i have one externally wired. I had this problem. went through three alternators and someone told me bout the volt reg and that was my problem. look into it.

 

also check for fusible links . and get the voltmeter out. if the battery reads 13+ volts , while the jeep is on then the battery is being charged

 

Same thing happened to me a few days ago. Tighten your serpentine belt. Even if it is just a little loose it will give you voltage drop.

 

In the cherokees after the Renix era there were in the ECU. But on the Renix like he has and I have they are in the Alt.

I would do like they said check your voltages with a meter. Then try to take it back to the store.

 

It is not at all unusual to get a DOA part, especially with alternators, and even MORE common with a rebuilt/reman. part.

Unless you stumble onto the cause, this alternator should go back to where you bought it.

 

I had the same issue on my Renix.
Undo the plug going into the firewall on the driver side and clean up the connections and put it back together.
It's a crappy set up with water getting in it.

 

So I fiddled with the volt meter. With engine on I checked the wire connected to the bolt on the back of the alt. and it was 12. Disconnected the plug with the 2 wires, yellow one had 12 volts and brownish one had .03 volts. I felt that because the brown wire had only .03 volts, it was likely the problem. My logical thought(my logic isnt always perfect though) was that this wire turns the charging off and on with a voltage signal. I thought I could rewire that line to a 12 volt signal and see if the car begins to charge. I cut the wire and before I could run the jumper wire to the battery, I discovered that the battery was charging at 14.5 volts!!! Can I leave it this way? What is this brown wire and what does it do? I drove it around the block with no ill effect.

 

14.5

 

If the wire looks stock and not third party, Jeep put it there for a reason. You need to follow that wire and check for shorts/burns but, if stock, it needs to be reconnected.