Check Gauges & Battery Indicator

[Zhillslady]

Now that she's run fine for a week or so she's back in the shop. This am I hadn't noticed the battery gauge but saw a "check gauges" light and then saw the battery charge was pegged out fully to the right. Called my mechanic but 30 miles away and recommended taking to old mechanic next door to office. I did notice when I drove it rest of way to work when I stopped the battery gauge went back to normal and didn't max out again till I hit 40-45 mph. Mechanic said didn't see anything wrong but I forgot to have him drive it over 45 or so so he's going to recheck. Any ideas he can check but I drive it 35 miles home tonight

 

[UPJOHN]

Sounds like a bad voltage regulator.

 

[UPJOHN]

What exactly is that/does driving make it worse?


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If the battery is being overcharged, it will be ruined.
The voltage is regulated by the PCM by way of a temperature sensor under the battery.

 

[Chris]

I agree that it sounds like it could be a bad voltage regulator.

 

[Zhillslady]

Well this mechanic said they drove it 3 times and couldn't get check gauge to come on and battery gauge shows normal so they left it at that. Thank you upjohn - when I called regular mechanic he said drive it home slow or have towed as sounded like voltage regulator and wondered why guy here didn't just test it.

 

[Chris]

Man, this think just never stops giving you problems, huh? That's the complete opposite of my TJ.

 

[Zhillslady]

Man, this think just never stops giving you problems, huh? That's the complete opposite of my TJ.

I'll be honest Chris, I'm at a loss with this Jeep. I've never heard of one vehicle having so many issues. My brothers 2001 and his 2010 are never in the shop. Our guess is all these issues with 137k miles is the prior owners just ran it to death and did little or no maintenance. I have found one guy from the local mud hole that said it saw it stuck on stumps twice and the girl literally just yanked it off with a friends jeep. That could account for a lot. Good news is I was going to order that Tom Woods drive shaft and while I was at this mechanic guy was looking over the jeep and asked how I liked her. Turns out he owns local drive shaft shop and said rebuilding my front shaft and installing it was a breeze. So short of my new upper doors that came in today that's my next repair.

 

[UPJOHN]

I agree that it sounds like it could be a bad voltage regulator.

I never had charging problems in so many years other than a bad battery, so I thought our TJs have a voltage regulator. I looked up voltage regulators up to see how much they cost. Nobody lists a voltage regulator. Upon further research I find out the PCM controls voltage. I'm so oldschool, but I learn something new every day.

 

[Ron505]

Batteries can intermittently act very quirky right before dying completely too. That should be an easy test though, that they should have done.

 

[Jerry Bransford]

It COULD be a bad voltage regulator or bad battery but I strongly suspect the actual problem is a lot simpler to fix, not to mention free. Remove both battery connectors and wire brush them and the battery posts so they are bright and shiny clean. Auto parts stores sell a wire battery brush for $3-5 that has a male and female wire brush made for this very purpose.

Then reattach both connectors tightly enough with the clamp nut on the connectors that you can't move the connectors around on the battery posts even with considerable hand pressure. That fixes most problems like this.

This problem is commonly caused by a battery connector that is corroded/loose/dirty enough that the voltage regulator isn't seeing the voltage from the battery so it keeps increasing the voltage from the alternator to the point the voltage indicator eventually pegs on the right side of the gauge.

 

[TJ4Jim]

Exactly what Jerry stated, the voltage guage was pegging on my son's TJ going down one of those poured concrete roads with the thump, thump, thump every 100 feet or so. Had to replace his negative cable as the clamp was beyond tightning properly.

 

[billiebob]

Over charging will kill the battery but maybe the gauge is the problem.
All the problems/solutions have been listed above. If not those...
If it were overcharging i think the battery would have exploded by now...
check the gauge. I hate the computerized "check engine" light.

 

[Jerry Bransford]

The battery has a temperature sensor located underneath it, its purpose is to prevent the battery from being overcharged or charged at too high of a rate which would cause the battery to get hot/overheat. The temperature sensor goes to the ECM which controls the voltage regulator that is built into the ECM. A bad connection at the battery can cause all kinds of problems but it won't cause the battery to overcharge.

 

[Zhillslady]

Thanks. I read this and son in law went and got me new cables today. Battery is month old as I replaced with the engine but the cables looked pretty shabby. Drove it home with no light so far. And as TJ4 mentioned that road I was on is really rough so hopefully that resolves it. If not I'll take back to my regular mechanic. Next is get my front drive shaft repaired. My new upper doors arrived today. Looking at new ones you realize how bad the old was. Thanks guys the advice helped.

It COULD be a bad voltage regulator or bad battery but I strongly suspect the actual problem is a lot simpler to fix, not to mention free. Remove both battery connectors and wire brush them and the battery posts so they are bright and shiny clean. Auto parts stores sell a wire battery brush for $3-5 that has a male and female wire brush made for this very purpose.

View attachment 2916

Then reattach both connectors tightly enough with the clamp nut on the connectors that you can't move the connectors around on the battery posts even with considerable hand pressure. That fixes most problems like this.

This problem is commonly caused by a battery connector that is corroded/loose/dirty enough that the voltage regulator isn't seeing the voltage from the battery so it keeps increasing the voltage from the alternator to the point the voltage indicator eventually pegs on the right side of the gauge.

 

[JPJEEPER]

It COULD be a bad voltage regulator or bad battery but I strongly suspect the actual problem is a lot simpler to fix, not to mention free. Remove both battery connectors and wire brush them and the battery posts so they are bright and shiny clean. Auto parts stores sell a wire battery brush for $3-5 that has a male and female wire brush made for this very purpose.

View attachment 2916

Then reattach both connectors tightly enough with the clamp nut on the connectors that you can't move the connectors around on the battery posts even with considerable hand pressure. That fixes most problems like this.

This problem is commonly caused by a battery connector that is corroded/loose/dirty enough that the voltage regulator isn't seeing the voltage from the battery so it keeps increasing the voltage from the alternator to the point the voltage indicator eventually pegs on the right side of the gauge.

100% fixed my similar issue...thanks for the suggestion!

 

[kcardwel]

hmmm; having the same problem and they said(mechanics) I needed to replace the computer since it is a 1998 and fuel injected. The regulator is incorporated into the computer.

 

[Jerry Bransford]

hmmm; having the same problem and they said(mechanics) I needed to replace the computer since it is a 1998 and fuel injected. The regulator is incorporated into the computer.

That it is fuel injected has nothing to do with anything. Yes the voltage regulator is in the computer but you can convert your charging system to use an external regulator, there's no need to replace the computer. Mechanics only like to replace stuff, they don't like to have to come up with ways to make something work without just replacing stuff.

But usually computer's regulator is fine, most charging problems have to do with corroded battery cables, bad/loose/corroded connectors, or the battery itself no longer being able to hold a charge. Having the battery "load tested" by someone who knows what they're doing is the only way to tell if the battery is good or not. And VERY few auto parts stores sales people know how to properly load test a battery. Too often a load test is done improperly/the load not held on long enough and they'll incorrectly pronounce a bad battery as being good.

 

[kcardwel]

thanks; willl look in to it more...battery cables look good but can check the battery out

 

[kcardwel]

Jerry; let me ask this...if it is the regulator and I can find a computer second hand specifically for the 1998 tj do you have to program anything? such as for the regulator or for the vin #? Can you just replace the new one.

 

[kcardwel]

Want to thank you Jerry...my son and law and I did further checking on the wiring and did find some corrosion and the posts clamps weren't on quite as tight as needed. So we cleaned things up and tightened and I drove it quite a bit with no overcharging problem. Will keep testing it and next weekend we are going to replace all the old wiring with new stuff so it will be even better. Thank you for helping so much...we need people like you to steer us in the right direction