Flickering dash lights 2000 K2500

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clevy04

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I have a 2000 K2500 and the gauge lights on the dash don't work. The far left light on the odometer and tach will flicker here and there. The light that comes on is red so the lights have been changed out at some point. I read that the headlight switch/dimmer switch may be the culprit but also what I have read on that says the HVAC lights shouldn't work either and they come and go. I have pulled the cluster out once but have no idea what I am looking at while its out.

Any thoughts?
 

Nad_Yvalhosert

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I have pulled the cluster out once but have no idea what I am looking at while its out.

Any thoughts?

Yes: Congratulations for taking on a project you dont know how to do!

That is precisely how most of us learn... by pulling things apart and seeing how they work. The rest of us purchase a Haynes manual and read the step-by-step instructions.

Happy learning.
 

1998_K1500_Sub

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Here's a picture of the back of a later-model GMT400 cluster (with credit given to @5vortec7)

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In this picture below, I've circled but a few of the many lightbulb sockets. These are twist-n-turn sockets, simply grab them with your thumb-n-finger to loosen and remove. Notice some are big and some are small, and even the colors are different (grey, white, black).

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I believe the bulbs are some sort of special, long-life type because most of them seem to last almost the life of the vehicle. (edit: See @Caman96 's post following this one /edit)

Replacement bulbs can be found, e.g., on RockAuto (look under 5.7L V8 > Electrical-Bulb & Socket > Instrument Panel Light Bulb).

ALSO, if you look closely at the bulbs as you remove them, you may see markings on them indicating the bulb part number, e.g., 74, 161, 193, etc. Those markings are your best clue to use for finding replacements.

The "long life" bulbs are typically indicated in their part numbers with an "LL", e.g., a 193-type bulb in "long-life" version will have part number "193LL". When you go shopping for bulbs, consider looking for the "LL" versions.
 
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Caman96

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This thread might help with bulb sizes.
 

Intragration

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Do the HVAC lights come and go in the same pattern as the odometer and tach lights? Meaning, when one flickers on and off, do the others flicker in the same pattern, or is their flickering random? Does raising and lowering the dimmer wheel all the way in both directions cause anything to happen? The dimmer is what's called a rheostat, it's basically a coil of wires inside. The common contact moves up this "coil" as you turn it, and the further away from the base it gets, the more resistance it introduces, which in turn causes the dimming effect. Rheostats can get dirty and not work well or have dead spots. If you "exercise" it, by running it up and down a bunch of times, this can sometimes clean it off and cause it to work better.
 

df2x4

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FYI, it seems like some people are able to reuse the twist lock sockets with new bulbs and others cannot separate them. If you need the complete bulb assemblies with the sockets included, the part numbers are PC74, PC160, and PC195. I'm not sure exactly how many of each you need, but you can get 10 packs of each of those on RockAuto pretty cheap. I was looking into this recently in another thread.

https://www.gmt400.com/threads/95-gauge-cluster-lighting-questions.59860/

EDIT - The part numbers for the HVAC controller bulbs are in there too if you want those.
 
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clevy04

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Do the HVAC lights come and go in the same pattern as the odometer and tach lights?
No, the HVAC lights either work or they do not.

Everything works on the dash minus the back lighting. And that will come and go so I'm unsure if the bulbs are the problem, last night I had a couple come on I hadn't saw work before. Also truck has an aftermarket radio, reading more on it makes me think that may matter.
 

clevy04

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Bump, I have a hard time believing its bulbs as they work sometimes.
 

df2x4

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Bump, I have a hard time believing its bulbs as they work sometimes.

If they're LEDs (you said one of them was red?) then I wouldn't be all that surprised. Tolerances for LEDs can vary wildly. Their bases could be slightly smaller or larger and not making contact properly, or some of them could be polarity sensitive and installed backwards. If I were you I'd put factory bulbs back in it and see if some of the issue goes away.
 

clevy04

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df2X4, if I'm looking at all this correctly, the large grey and black are labeled ILL I'm assuming that illumination? So three 161 and three 194? Do I just grab bulbs and hope the base comes off for now since the bulbs could be had locally?
 
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