over40driv

My daughter has a 2004 Pontiac Sunfire that has recently had a gauge problem, in the fact that the tach, gauge needle is pegged out to the right and the speedometer needle is not moving. Sometimes it works and sometimes not Thanks

mikez

Does the gauge get stuck to the right when the car is off?

The gauges, both tach and speedo are operated by a electrical generator, it takes the rotational output of the motor or wheel, and converts it into an voltage output through a generator, then the voltage will deflect the needle certain increment.

The modern day car has another system in there to smooth out the current input so the needle don't deflect randomly or bounce up and down when the car is started (the IS does this for show, but it is how the gauges look on older pre 50's cars).

If your gauge is unstuck and comes back to initial point when the car is off, then its most likely the generator's problem or the electrical unit smoothing out the needle's fluctuation is malfunctioning. If the needle is still stuck when the car is off then either the needle deflection thing/motor is broken or stuck.

As for your speedo working some times and not others, it can be all of the above.

To sum it up: electrical problem, can either take apart and replace each of the component to trouble shoot, or replace the whole gauge and see if the fault lies within the generator... which is harder to replace.

I would say its a faulty gauge/dash thing.

over40driv

The tach needle is def. pinned over to the right with car off. Where would the speed gen. motor be? I thought it ran off the alt. but it seems to be working good.

mikez

That I don't really know, I just know the basic design and how it is suppose to work, but where they place the generator and getting the rotational speed itself I have no idea :/

Most of the component itself however should be right behind the dash/gauge, the motor/voltage deflector thing for the needle etc, and most likely the fault should be there. With the tach needle pinned there it the fault would definitely lie in the gauge components, since there is no current running with the car off, the gauge would be able to raise itself to that position without something pushing it, something must have burnt out and died there leaving it in that position.

Another thing I know is the cruise control runs off the same control loop as either the speedo or the generator itself, I don't know if you had cruise control (or have the ***** to test it with a broken speedo), you can see whether its the just the gauge cluster that is broken (cruise control works, or the car accelerates non stop) or something worse (cruise control doesn't work).

Do you want to take apart the gauge cluster or something? I think you might get a better idea why that thing is stuck from looking at it from behind.

over40driv

Yeah, I think your right, with every thing off the tach needle should be down. Think its time to take it to the dealer. Thanks

mmarshall

Have either the dealer or an independent repair shop check for a TSB (Technical Service Bulletin), Pontiac extended-warranty coverage, or a recall before actually starting the work on the repair. A TSB, if applicable, will explain the problem in detail and exactly what parts and repair procedures are needed to handle it. Auto manufacturers sometimes have unannounced longer-than-average warranty coverage on parts and systems that prove troublesome in service....but often you have to ask about them. If there is a recall (which, in your case, is unlikely), that means it is a safety problem and automakers are required by law to address it.....they have no choice.

Obviously, the dealer would be the best place to find out extended-warranty or recall coverage. An independent shop is probably not going to talk themselves out of your buisness by telling you the dealer is responsible for repairing it. But, if you do wind up at an independent shop, at least make sure they have a Mitchell-on-Demand or All-Data system that can check for a TSB.

over40driv

Good idea, didnt think of that.