1984 - 1989 Corvette: Digital Dash Cluster Repair
From Bob Golden:
My name is Bob Golden and my home e-mail is <withheld>. I wanted you to now how I enjoyed reading your publication on the repairs of the famous digital cluster.
For 20 years I was the General manager at Speedometer Service, Inc. in Carrollton Texas. It was bought out and is now called Autocraft. Their address is 1612 Hutton Dr. Suite 120 Carrolton, Tx.75006-6675.
Phone 972-466-6200. They are one of the few left that still remanufacture Clusters for AC-Delco. They may be another source for you. I’m no longer there but I know the technical staff and they are very good.
I have attached a short help sheet I sent out to some friends and thought you may want to have it. If you contact Autocraft ask for Tommy Terrell. He was the original repairman that was used by Delco on these clusters. I remember they used to have some new clusters that were never used because they did not have cruise control circuits in them. You may want to inquire about these for parts. By the way the cruise control driver transistor P/N was 16008121 a number I came all too familiar with.
1984-1989 C4Instrument Cluster Issues
Having your instrument cluster repaired or exchanged can be a costly item.If indeed you must have this done call the experts first.There are only a few authorized remanufactures still around that can do this type of work. Whichever you choose go direct and save.Ask your GM dealer for the AC-Delco remanufacturing center nearest to you.However, many times this is not necessary if you know the tricks.
LCD displays must have backlighting to illuminate.Many times all you need to do is change the bulbs.These bulbs can be changed by simply removing the plastic panel covering the instrument cluster.Pop out the metal bulb covers and with the use of some shrink tubing you can grab the bulb and work them out.Shrink tubing can be purchased at Radio Shack or any electronic supply center for peanuts.Buy the size that will fit over the bulb snuggly.After you have pushed it over the bulb, heat it for a very brief 2 seconds and pull the bulb out.To re-insert a new bulb use a similar method without the heat.Avoid touching the bulbs with you fingers.Body oil will causes heat spots and shorten the life of a bulb.These bulbs can be purchased through your GM dealers.
A better suggestion is to remove the entire cluster and replace both the sockets and bulbs.This requires a little more work but will address the intermitting type of display black out.You will have to remove the tin panel covering the back of the cluster however this is very easily done.
If you experience a complete blacked out cluster, check your ground first.The most common ground found to be loose is G401 located rear of engine below left hand valve cover and is sometimes disturbed during maintenance.