1990 - 1996 Corvette: Fixing Erratic Digital Display
Submitted by: Gorgon
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 dis-assembly 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.
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