Jeep Having problems with your XJ dash?

[TooeleBronco]

About a year ago my dash would randomly quit working and sometimes my voltage gauge would read that it was over charging. It never happened at the same time and didn't happen that often. Every time I had time to work on it it would be working fine. I changed the alternator and the battery but the problem was still there. I Googled it and most people said that the problem was behind the dash with the wiring or the ground. I checked that but couldn't find any problems. Some people blamed the ECM since that's what acts as a regulator for the charging system. I considered throwing one of those at it but they are a bit pricey so I decided to hold off till I knew that was the problem. Then I found a write up online somewhere where the guy said to check the battery temperature sensor under the battery. That's a simple test with an ohm gauge. It tested bad. I spent $35 on a new one and haven't had a problem since. The battery temp sensor decides how much charge to throw at the battery depending on the temp of the battery. If it's putting out too much charge it can trip the dash. This seems to be a common problem and most of the sources I looked at blamed other things. Maybe it is other things sometimes but this is an easy check and fix if this is the problem.

My Jeep Cherokee is a 98 with the 4.0. I would imagine that this could be the problem for other years and/or models.

 

[gatchmo5710]

Ive always had weird things with my dash. Volts reading low even though alternator is putting out 14+-, oil pressure always high, etc. I wonder if we could hard wire a resistor to bypass batt temp to make alt put out constant voltage??? What should the correct resistance be on a new batt temp sensor? What did your bad one show?

 

[TooeleBronco]

You'll have to Google it because I don't remember how much resistance it's supposed to have but I'd check that first. It's easy to check and could make the charging go either way depending on what it is reading.

 

[thenag]

That is good to know, I have that sensor on my 99.

I have actually relocated it to the side of a sideways mounted yellow top and haven't had any issues with it.

I kind of guessed what to do with that sensor when I stuffed two batteries under the hood, it sounds like I didn't screw it up.

Nathan

 

[Jinx]

Cool post!

Thanks for sharing. Things like this make RME great!