I am offering this write-up for those that have problems with the digital dash of the 90 to 96 model Corvettes. This interior has analog gauges with a digital LCD in the center of the instrument cluster.

My experience with the LCD was when a bump was hit the digital display would scramble into a total unreadable mess. A quick tap on the instrument cluster would bring the LCD back to reality an display normally. This behavior had all the characteristics of a ground problem.

I started by removing the instrument cluster from the dash. This will require dropping the steering column to get the cluster out, but it's very easy to do. Once the nut is removed from the bottom of the column it will drop without a problem. Then the screws are removed from the instrument cluster and this is pulled straight out.

The following picture is of the dash with the cluster removed. Here you can see the connector where the signals enter the instrument cluster.



And here is a close-up of that connector.



Carefully disassemble the instrument cluster. My apologies for not having better pictures, but I was intent on getting pictures of the problem and not the step-by-step of the tear down and assembly process. :(

Care needs to be taken in the removal of the rear PCB from the cluster. It comes apart a little hard. You need to be careful of the analog gauges. The tach has a built in stop at the zero mark. Needless to say mine now sags to the bottom instead of zero when the car is off. When the key is turned to the ON position it jumps to the zero mark and works normally when the car is started so it's not that big of a deal. :)

The next shot is of the PCB (Printed Circuit Board).



Here you can see the illumination lights and at the top of the board is the group of wires and orange connector that goes to the LCD. The white connector on the PCB with the green wires is soldered to the board so you cannot remove it from the PCB.

Here you can see the LCD upside down.



On the top of the LCD you can see the pins that go to the orange connector. The LCD was plugged into the orange connector as shown below.



I took the PCB and LCD and placed this in the car by holding the PCB in the dash. Playing with the pins on the LCD I could make the display come on correctly or scramble. A close look at the pins showed that one pin had lifted ever so slightly off the glass. In this pic it is the far right pin.



On the back of the LCD the pins are glued to the glass using adhesive similar to that used to attach rear view mirrors to windshields. I used an exacto knife to cut this adhesive and remove the suspect pin. I bent the part of the pin that connected to the glass so that it applied pressure to the glass. The electrical signals enter through contacts on the top of the glass so the adhesive on the back does not interfere. Once the pin was placed back on the glass use some window adhesive to apply to the pin and let it set. Reassemble the instrument cluster, put it back in the dash and reassemble the rest of the car. I did this on my car 15 months ago and have not had any problems since.

Sorry for the lack of pictures in the disassembly process. I have the 95 shop manual and can add pictures from that if they are needed to disassemble the dash. And I also cannot accept any responsibility for damages that are caused by following this procedure. :)

Leon

BTW, Hi, I'm a new guy. :seeya


[Modified by Gorgon, 9:28 PM 11/4/2003]

 

sweet!

and welcome!!!

:seeya

 

Thanks! :thumbs:

 

Some people know how to make an entrance. :cheers: Welcome aboard, that ia an excellent write up. I hope you submit it to the 'Tech Tips' section so it can be kept there for all to see. :seeya

 

Welcome Leon! :cheers: Its nice to have an electrical engineer aboard :D Thanks for the great tips! :seeya


[Modified by bradvette, 7:30 AM 11/5/2003]

 

Thanks for the welcomes. I had replied to Ken's (My95) thread about his dash though he was talking about an 85 dash. I received an email about from another member here about this particular problem so I dug up an old post I had over at CAC when I was originally working on this and did the write up for here.

What needs to be done to submit to the tech area?

Leon :cheers:

 

Cut and paste it here:

https://www.corvetteforum.com/techtips/submit.php

Great job!

 

Submitted. :jester

 

i tlooks like the LCD is transparent, does that mean that the orange color backlight is a seperate piece?

 

The glass is clear with the LCD segments on it. There is a translucent piece of plastic that is orange in the center and the top has two green squares for the turn signals on the top corners and a blue square in the center for the high beam indicator. I didn't happen to catch that in any of the pics that I took.

Leon

 

could it be seperated with out damaging anything?

 

Could what be separated? The translucent plastic is one piece. But it just sits in the cluster behind the glass. Any I understanding your question?

 

If you're thinking what I'm thinking.. I like that idea.. out with the ugh orange LCD.. In with the <insert favorite color> LCD :jester

 

i was thinking white face analogs, indiglo LCD

 

WELCOME I have been searching for this type information. Do you know what you did to make the tach needle drop below the post? :hurray:

 

I don't think there was a post at the zero mark. There was a stop inside the coil on the PCB. When I was reassembling the cluster I hit the tach needle and felt something give. It hangs now because of that. I didn't look too closely at it at the time as I wanted to get the LCD working. I hadn't installed the clear plastic lens yet and that's when I hit it. :sad:

 

LCD Fuse is drawing 4A and draining battery on 92 corvette anyone know what might cause this