Driving for work the past few days the truck has developed an interesting issue. My water temp gauge and oil pressure gauge are reading high. Maybe 1/2 a notch higher on the gauge. Voltage gauge does not move at all. I was thinking mechanical problem until I saw they were both high and thought it could be electrical. I have my blower motor on a relay and my headlights. My blower is running on high all the time. I was playing with the fan and if I take it off high it will come down some although not back to normal. Turning headlights on makes it go up and turning them off makes them go down but again not all the way. Then it will all go back to normal and the blower and headlights have no affect. First time it did it, it stopped when I was playing with the headlights on the freeway. Second time it didn't go away till I shut the truck off. I know voltage can play a role on where the gauges read, but my fuel gauge (although the fuel gauge reads pretty slow so I cant really tell what is slosh and what could be this issue) and voltage gauge seem unaffected. Batteries are dual redtops about 3 years old. Have not done any testing yet, I spent today recovering from a LONG week of work. What should I check out tomorrow? Thanks guys!

Aaron

 

Check your charging voltage, 13.8 would be nice, 14.1 would be OK and 14.4 is getting a little high.

The next thing to look at is the main body ground. That will make the gauges do all kinds of wacky things.

 

So would high voltage make the gauges read high or low? I figured when I turned the lights and blower motor on it would slightly drop my voltage but the gauges go up. I still find all of this very odd since the voltage gauge does not move, it sits in the same spot it always has. Maybe the alternator senses the extra load and increases its output??? Does the alternator increase its output based on load or does the computer control that? It is the original alternator. Maybe time for a new one. Thanks!

 

It does. If you put a voltmeter across the battery before and after you turned those on, you'd get different readings.
My gauges read different when my headlight switch is on or off, and I know it's a bad ground, (I just haven't got around to fixing it ). I'd be looking to that first, and moving on from there.
The voltage regulator is the thing that controls how much current goes back to the batteries.

 

The computer does control the alternator. There isn't a voltage regulator on your truck unless someone put it on there.

 

I apologise. Not trying to misinform. Guess I'm used to Class 8's.

 

No mis-information there, just a difference in year models.

1989 - 1991, non-I/C AND I/C, have a normal external voltage regulator that controls the alternator.

1992 and 1993 have no regulator and the alternator is controlled by a computer .


It is common to retrofit a regulator onto the 1992-1993 trucks whenever the computer fails to properly monitor the alternator.

 

Ahh, I was half right!

 

Ok so didn't find much out. Last time I tried to use the multi-meter it needed new batteries. Now I have new batteries. Now I can't find the stupid multi-meter...... I checked the body ground. It looks fine. Perhaps a little small, but its in good shape. I would think if it was over charging, my dash voltage gauge would read high. It sounds like a ground issue to me. I am going over to a friends house later and I'll check the voltages with his meter. Another thought I had was on the old mopar cars the water temp and oil pressure gauges ran off a lower voltage and there was a small voltage regulator on the back of the instrument panel. It would cause those two gauges to read funny if it was bad. The ammeter and speedo and tach were not on this and therefore unaffected. Do our trucks have this setup? Or do the gauge signals go through the computer? Thanks for the suggestions guys!

Aaron

 

I just went and checked a cluster I have in the shed and there is not a regulator on the back of it. I know what you mean my duster has one of them on it.

 

Hidden somewhere under the dash is a GROUND that can cause a host of electrical problems.

Find it and clean it, then add a big jumper from it to a better GROUND.

It seems like these models of Dodge are plagued by Chrysler being stingy with the GROUND; you cannot have too many or too big of GROUNDs; the more/bigger, the better.

 

Its been a little while I know but I think I have solved the problem. I added a ground from the dash to the firewall and also added an extra ground from the radiator support to the battery and it went away. Just a case of not enough ground I think. I also took apart the instrument cluster to check all the contacts but they all looked fine and I don't think this had anything to do with it. I have slowly added more electronics (gauges, radio, brake controller) and also increased input to the headlights and blower motor without increasing the size of the ground. Thanks for the input guys!

Aaron