Legocar

my dash says i am running around 18volts,what could casue that? or coudl if be a faulty dah gauge......if it is at 18 is that super bad? ha yea im a newbie.

Gee oh Dee

Verify actual voltage with a multi meter.

Factory gauges are known to be less than accurate...

Legocar

lets hope so!
lol

Gee oh Dee

If you were pushing 18v through the system you'd probably know it.

Your battery would boil over, wires would probably smoke, lights would look awfully bright, etc...it wouldn't just be a gauge reading funny. There would be other symptoms.

Nakedginger

Yeah, I just had a issue with high voltage. Go over to the battery and check what the voltage is. When I checked mine it was around 16.5 volts. I noticed that my aux fan rpm was much higher and a higher pitch noise. Along with this, my head lights were very bright. If this is the case for you it sounds like your voltage regulator is dying. If you have a pre 91 XJ the regulator will be inside the alternator otherwise its external. I have a 90 XJ so I had to get a new alternator. BUT it could also be your gauge. I am having problems with my voltage gauge reading too low. I'm most likely going to rip it out and put an after market one in its place.

highmileage

If you're getting 16.5 at the battery it's the regulator, volts shouldn't be over 15.

highmileage

You can wire in the new gauge, but the problem isn't the gauge. The wiring to the gauge is in line with other stuff and the volts get robbed from the gauge not the system.somewhere around the starter relay is the problem. There's a recent thread about this and the fix.

highmileage

"Voltage drop when blower motor is on", that's the thread that has the fix

Nakedginger

Yep, I' started that thread when I thought the blower motor was drawing lots of amps. After hearing about the fix, I pulled the gauge out of the cluster and tested it at the battery with some extra wire. I read what voltage was across the posts with a volt-ohm meter and then compared that value to what the gauge was telling me at the battery. I came to find out that the factory voltage gauge is very inaccurate in how much the needle travels compared to what the voltage actually is. Because of this, I am wanting to put a more accurate gauge in. Just some of my findings

highmileage

Right on

I'll keep that in mind whenever I decide to rectify my gauge.

cruiser54

Actually, the later models have a voltage regulator inside the PCM, not external.

Nakedginger

Sorry, I miss spoke. I ment external to the alternator. I have a 1990 and know after that the voltage regulator isnt in the alternator. Its nice to know its in the PCM though.

cruiser54

Be glad yours is inside a cheap to replace alternator rather than inside an expensive PCM.