The LCD in my car is weak. I can still see all the readouts but nothing changes with the dimmer switch turned. I don't know if that controls it...to be honest, I know nothing about an LCD in a car at all. The brightness of the screen doesn't change for anything. Is this something I can fix, a local electronic repair shop can fix, or do I need to send it somewhere to be fixed? Any ideas on the cost of repair for any of these options? I'm sure its beyond my scope for repairs but what to do with or about it?

That isn't as simple a question as it first appears. There are several different fuses that feed the digi dash on a 1984 - 1989 Corvette. There are the "Inst Lps", "LCD", Tail", and "Inst Cluster" fuses, and possibly more. The brightness should change by rotating the head lamp switch knob, when the lights are on. There is a photocell in the circuit that also changes the brightness. I would start by checking all the above fuses. I have had a couple of "foolers" that looked good, but failed a continuity test. Next, I would head for Batee (http://www.batee.com/corvette/dcrg/repair.htm) and their primer on trouble shooting and repairing the cluster. Your problem sounds more like a lighting circuit problem than a non-functioning cluster. I just went through all this on mine. I sent it out for an overhaul after checking and re soldering everything. Good luck.

RACE ON!!!

You may also want to check and make sure you don't have any telltales (out of range guage readings) as it will keep the LCD at its brightest as a secondary telltale.
Woody:burnout:

When I rotate the knob, nothing changes in brightness although the other working interior lights will dim. All those fuses mentioned are good, but I concede that there could be a break in the wire somewhere. The previous owner hacked lots of wires in the dash. I can read the displays during the day but at dusk I can't see a thing. I'll need to get into the dash and see whats going on. I wasn't sure if this was a sign the LCD was going out or was just faded badly, but nothing I do makes it change. Whatever light illuminates the odometer reading is out but I don't know if that is related. I still have to replace the headlight actuator module...would this part effect it too?

I can read the displays during the day but at dusk I can't see a thing
Is the cluster illuminated during the day? How about at night, with the engine "Off", key "On"? Try this: At night with the engine running and the lights on, shine a light into the photocell. Does the cluster brighten?


Whatever light illuminates the odometer reading is out but I don't know if that is related. I still have to replace the headlight actuator module...would this part effect it too?
There are 4 bulbs, number 882, that illuminate the cluster on my '84. Make sure none of yours are burned out. The head light actuator module should have no effect on the cluster.

RACE ON!!!

[QUOTE=CFI-EFI;198222]Is the cluster illuminated during the day? How about at night, with the engine "Off", key "On"? Try this: At night with the engine running and the lights on, shine a light into the photocell. Does the cluster brighten?

I'll try that Friday and get back with you on the results. To answer the first part of the question, the cluster is illuminated during the day but barely. Can you tell me where the photocell is located? I'm thinking its the square port located above the speedometer gauge but I'm not sure if this is correct.

Can you tell me where the photocell is located? I'm thinking its the square port located above the speedometer gauge but I'm not sure if this is correct.
That is correct.

RACE ON!!!

I tried the test you recommended and there was no change in the brightness. What does that mean? BTW, I liked the link to the article on rebuilding the LCD.

I tried the test you recommended and there was no change in the brightness. What does that mean? BTW, I liked the link to the article on rebuilding the LCD.
That sounds like a bad photocell. The flash light shining on it in the dark, with the lights on should brighten the cluster.

Wait. I may have misled you. Does the cluster ever brighten? Daytime, nighttime, lights on or off? Mine worked in the daylight. If yours is never bright, I think you have bigger problems. The photocell and the rheostat on the headlight switch work together to control brightness. You can check the photocell, but when mine went totally dark, where I couldn't see any readings, my power supply was shot. You may have to send it in for repair as I had to. Good luck.

That sounds like a bad photocell. The flash light shining on it in the dark, with the lights on should brighten the cluster.

Wait. I may have misled you. Does the cluster ever brighten? Daytime, nighttime, lights on or off? Mine worked in the daylight. If yours is never bright, I think you have bigger problems. The photocell and the rheostat on the headlight switch work together to control brightness. You can check the photocell, but when mine went totally dark, where I couldn't see any readings, my power supply was shot. You may have to send it in for repair as I had to. Good luck.

No, it never brightens. I think your right about it having bigger problems. The previous owner ran this huge stereo wire to the door speakers, secondary to hacking many wires behind the dash when installing a CD player (that was eventually stolen) and I've noticed that the dash was also removed once before, probably during that installation. The power wires for an amp are still there as is the cable for a disc changer. Even the rear hatch release on the door doesn't work and the windshield wiper switch barely operates.

I'm probably just going to have to take the dash out and find out exactly what was chopped and what it goes to, or find a complete wire harness and just replace all of it. I was trying to rule out everything possibly related to the operation of the LCD before seeking professional repair...I hate tossing parts at something hoping that it eventually fixes it...not how I roll. I'd like to fix the LCD myself since there isn't anything else on a car I can't fix, but, I don't have the precision or patience to solder small electrical components like in that article. I wanted a project and I'm glad to know I'll be getting my money's worth. Thanks for your help, that's more than I knew about LCD's and troubleshooting them.

Yes, if it never is bright, it probably isn't the photocell. With your hacked wiring, if you can wait, you might want to hold off on the professional repair of the cluster until you have the wiring straightened out. The cluster repair isn't cheap. It would be a shame to pay to have it overhauled if it didn't need it. Good luck.

RACE ON!!!