Discharged battery

[mr.fitness350]

I have a 1999 Jeep Grand Cherokee V8 with all-time 4 wheel drive. The battery is completely discharged. The alternator isn't sending any power to the battery. There is a thin fried looking green wire leading from the back of the alternator to the battery. I'm assuming that's the problem, but I want to be sure. I think it could also be a fuse that's out or the regulator in the computer that controls the alternator could be out too. But there's nothing wrong with the computer at all. I've never had any problems with the computer. The battery is only a few years old and the alternator is too and they both seem to be just fine. So as far as I know it's either that wire or a fuse. Any suggestions?

 

[SteelHeadz]

Trace that burnt wire and make sure its not shorted to or burnt into another wire. Replace the wire with the same gauge. Check under the battery and look for a battery temperature sensor if equipped. Make sure the sensor wiring are good and connected properly without corrosion. The PCM controls the charging system with the help of that temp. Sensor under the battery. In some cases , the signal from the sensor will fail and causes the PCM to continually switch to a full field charge to the battery from the generator. This in turn will get the wirings hot and if already old and brittle, will eventually burn or short out to another wire.

 

[greg92jeepxj]

Trace that burnt wire and make sure its not shorted to or burnt into another wire. Replace the wire with the same gauge. Check under the battery and look for a battery temperature sensor if equipped. Make sure the sensor wiring are good and connected properly without corrosion. The PCM controls the charging system with the help of that temp. Sensor under the battery. In some cases , the signal from the sensor will fail and causes the PCM to continually switch to a full field charge to the battery from the generator. This in turn will get the wirings hot and if already old and brittle, will eventually burn or short out to another wire.

Thanks for the explanation of the battery temperature sensor . Have tried to get in contact with my brother who owns a '99 grand cherokee and recently had to replace this sensor. He explained that the charging system is affected by it and must be replaced or the alternator will be affected . Although my brothers '99 did not experience any engine harness issues as he made the repair timely , I thank you for the detailed explanation as this post shows cause and effect with full explanation.
Just sorry that a new member had to be a victim. Great to have certified technicians in our forum . Hope my brother still has his research data from his repair for me to examine , if he calls me back. Lol. Thank you again . Greg

 

[SteelHeadz]

No problem Greg, glad to have you on board with your knowledge and experience. Keep up the great work!!

 

[greg92jeepxj]

No problem Greg, glad to have you on board with your knowledge and experience. Keep up the great work!!

Thank you sir , great to be here and always willing to share my street level technical assistance but am honing it to modern specification through research and learning from folks such as yourself. Thank you again. Greg