low voltage gauge reading

[87National]

I am seeing a reading of around 10 volts on the voltage gauge in my 86 442. It is constantly 10 volts whether cruising, idling, headlights on, etc.

I checked voltage at the battery and alternator with a multimeter and am seeing around 14 volts. Things like headlight brightness, power window speed etc. function normal and do not indicate a problem.

So could the gauge in the dash be reading a little low? I realize that the reading for the gauge comes from the ecm, and some voltage drop is to be expected - but certainly not 4 volts.

My background in auto electrical issues is limited. Maybe someone can chime in here with some advice.

 

[jrm81bu]

I'd say that's a fairly common problem. It's probably due to a poor connection in the circuit board thing behind the guages that powers all the guages.
Any of the other guages acting funny or reading a little odd?

 

[kingcolbert83]

could he run it directly to the source with a relay and fuse instead of runnin it through the ecm?

 

[jrm81bu]

It would still have to go through the circuit board to get to the guage.

 

[kingcolbert83]

i was thinking more on the lines of like with a carb car. Isnt a gauge you buy from autozone hooked up directly with some protection or is it ran through your current circuit? i just have the dummy light in mine so not sure how the aftermarket gauge works.

 

[87National]

I'd say that's a fairly common problem. It's probably due to a poor connection in the circuit board thing behind the guages that powers all the guages.
Any of the other guages acting funny or reading a little odd?

Yes, the fuel guage reads 3/4 full even after a fill-up, and occasionally when starting the car, none of the 4 small gauges will register, they will remain stuck at wherever they were when I last drove it.

Thanks, I just wanted to make sure I'm not missing something.

 

[87National]

It could be challenging to wire the stock gauge this way. However it would be easy to mount an aftermarket volt gauge and run a wire directly from the alternator - just for peace of mind.

could he run it directly to the source with a relay and fuse instead of runnin it through the ecm?

 

[joeairforce]

None of the gauges on these cars go through the ECM. All of the ECM sensors are just for the ECM. The problem is the connections. If you just take your cluster out and and apart and clean all the connections real good and tweak all the contacts so they get a better connection it should fix the problem. It did on mine anyway.....

 

[87National]

On my Grand National, voltage is read at the ECM. I just assumed that was the case on all g-bodies.

None of the gauges on these cars go through the ECM. All of the ECM sensors are just for the ECM. The problem is the connections. If you just take your cluster out and and apart and clean all the connections real good and tweak all the contacts so they get a better connection it should fix the problem. It did on mine anyway.....

 

[G_Body_Enthusiast]

the copper circuit "board" on the back of gauge cluster like in the grand prix can turn green, thats corrosion which means extra resistance in the circuit. this alone can make your gauges act funny and misread by 1/8 of a tank to 1/4 of a tank for fuel level for example. more importantly where the plug in the dash goes into the cluster, make sure those contacts in the board are bright and shiny. if they are then you need to look elsewhere, like replacing the whole circuit board which isnt hard, they're universal so you can yank it out of a car with idiot lights, the boards are wired for idiot lights AND gauges and use different paths.

check that first and if need be, replace it and see how they act then go from there. but i;m gonna guess it might be the circuit board/connections to it on the back.