Dash lighting slowly come on their own?

1999 BUICK CENTURY
163,000 MILES • 3.1L • V6 • 2WD • AUTOMATIC
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THEMAILMAN
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Over time, the PRNDL and odometer, along with 1 section of lighting have quit. What I mean by over time is that they would eventually slowly come on their own, or if I cranked the brightness on the headlight switch up and down a bunch of times. Also, it seems the dome light has quit too, although I have to double check the bulb itself. Looks okay, filament is in place, but you never know.

I'd really like to be able to accurately track mileage, as this is a deduction and a known amount to of mileage on the cluster is always better than a TMU car.
Aug 22, 2022 at 10:16 PM
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STRAILER
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It sounds like the rheostat inside the headlight switch is going bad. I would change the headlight switch out to fix the problem. Here is how in the diagrams below. Let me know if you have any questions.
Aug 23, 2022 at 3:52 AM
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THEMAILMAN
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Sorry it took me so long to get back. Life's crazy like that. I grabbed one at the junk yard. I was there for something else and saw this car there with the dash already apart, and the switch looked new. Put it in no change. I also realized that the radio and center console lighting does dim and brighten as it should at all times. So I'm thinking there must be a power wire going from that switch to the odometer/PRNDL. The issue would be in that wire or in the cluster itself. I'm leaving towards the cluster itself. Maybe cracked solder joints. Before the solder would expand with heat as the car warmed and eventually make good enough contact to work. Eventually the cracks became too large.

Does that sound plausible?
Oct 21, 2022 at 6:00 AM
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STRAILER
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Yes, it does, I was going to suggest the cluster but it won't have an effect on the other lighting issues. Here is how the lighting works so I would check the three fuses that run the system and the lighting ground confection. Here are the wiring diagrams so you can see how the system works and which fuses to check.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Check out the images (below). Please let us know what happens.



Oct 22, 2022 at 6:01 AM
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THEMAILMAN
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The ground wire seems like a viable option. I'll check that. If I'm reading correctly, it should be the one going to the firewall, below the dash, left of the steering column. After that, I've already got half of the dash apart because I'm swapping the stock radio out for one with Bluetooth that I got out of a parts grand am, so it's only a few more screws to pull the cluster and look at the solder joints. If I see something there, I've got a tiny soldering iron and some rosin core solder that I've used on laptops that might do the trick.

As for the dome light, I'm not terribly worried about it. I keep forgetting to get a bulb to check that possibility, even though I'm in AutoZone weekly because I use and abuse my cars heavily (they're proper workhorses).

But this one I kind of want to bring back for use as a daily and a backup workhorse.
Oct 23, 2022 at 7:32 AM
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STRAILER
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Okay, it sounds like you are on the trial to fixing it let me know what you find please.
Oct 24, 2022 at 4:45 AM
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