Voltage regulator failure help
Thread Starter
Newbie
Joined: Sep 2017
Posts: 1
Likes: 0
Year: 2001
Model: Grand Cherokee
Engine: V8
Voltage regulator failure help
Okay the other day had a long day of driving around the city and and then the car started to ding, with a light saying check gauges. The battery was losing a charge quickly. After stopping at the parts store to check/charge battery, the battery came back "Good". Battery is about a year old.
Took the car home, and the battery was good for almost a day. When the dinging started again and the battery was draining. Took the battery back, charged, still "Good", changed terminal connectors because that were bad. Took the car to the parts shop, run tests on the battery while the jeep was on, and the Voltage regulator failured.
Im seeing that I may need to change the PCM. Though, I'm curious about other thoughts and direction. Can this be an alternator problem? Or should I look elsewhere first?
Took the car home, and the battery was good for almost a day. When the dinging started again and the battery was draining. Took the battery back, charged, still "Good", changed terminal connectors because that were bad. Took the car to the parts shop, run tests on the battery while the jeep was on, and the Voltage regulator failured.
Im seeing that I may need to change the PCM. Though, I'm curious about other thoughts and direction. Can this be an alternator problem? Or should I look elsewhere first?
Senior Member
Joined: Sep 2013
Posts: 518
Likes: 3
From: Santa Cruz Ca.
Year: 2000 WJ
Model: Grand Cherokee
Engine: 4.7
I have a 2000 with the V8 and it does not have a voltage regulator and I don't believe yours does either. What does your volt gauge show? Charging? Or not charging? Check for codes. That should point you in the right direction.
Last edited by blueseasons; Sep 7, 2017 at 09:14 PM.
Old fart with a wrench
Joined: Nov 2010
Posts: 14,398
Likes: 740
From: Manlius, east of Syracuse, NY
Year: 2000 XJ Sport & WJ Laredo
Model: Grand Cherokee (WJ)
Engine: 4.0L
Welcome to CF!
Underneath the battery, there is a temperature sensor. It's purpose is to monitor battery temp to tell the PCM to reduce the charge rate when the battery gets hot. It's just a variable resistor and doesn't cost much, but if it's shorted or open, can cause the alternator to not charge properly. It's just a button thing mounted in the battery tray and has a 2 wire plug. You can pull it out and check it's resistance. (or just replace it)
You can take out the alternator and get it checked at an automotive electrical shop. If the alternator is charging, the dash gauge should show just under 14 volts.
CHECK ALL YOUR GROUNDS!
Underneath the battery, there is a temperature sensor. It's purpose is to monitor battery temp to tell the PCM to reduce the charge rate when the battery gets hot. It's just a variable resistor and doesn't cost much, but if it's shorted or open, can cause the alternator to not charge properly. It's just a button thing mounted in the battery tray and has a 2 wire plug. You can pull it out and check it's resistance. (or just replace it)
You can take out the alternator and get it checked at an automotive electrical shop. If the alternator is charging, the dash gauge should show just under 14 volts.
CHECK ALL YOUR GROUNDS!
Last edited by dave1123; Sep 8, 2017 at 04:23 AM.
CF Veteran
Joined: Jan 2012
Posts: 2,208
Likes: 5
From: Ocean County, NJ
Year: 1998
Model: Cherokee
Engine: 4.0L
I installed an external voltage regulator on my WJ. It was actually overcharging at like 18 volts. That makes for an interesting running engine. Nevertheless, I installed THIS and my charging issues are gone. I don't trust remanufactured computers. I've heard too many bad things about them and it's not worth swapping the entire computer simply because the internal voltage regulator is on the fritz.
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