85 Instrument Cluster Problem
Thread Starter
Instructor
Joined: Dec 2007
Posts: 184
Likes: 4
From: Hilliard OH
85 Instrument Cluster Problem
Hi All,
I just purchased an 85 Coup with 70,000ish? miles. Previously, it sat outside in the hot Arizona sun on blocks for over five years, and became a home to several woodland creatures. After cleaning all of the grunge out of the car it started right up. Everything runs fine except the digital dash. The only thing that lights up is the "Check Engine" light.
I took the cluster and center display panel out of the car & did a visual check on the wiring harness. There doesn't seem to be any evidence of rodent damage. (There is damage to other areas, like the taillight wiring.)
Is there an easy way I can determine that the cluster itself is not faulty?
Where should I focus my efforts to find the problem if it is in the wiring?
This car is only going to be a dedicated AutoX car. It doesn't need to look pretty, but I do need some working gauges.
Thanks for any help you can provide.
Later,
BeerMan
86 Rag Top
85 Coup (#71 XP)
I just purchased an 85 Coup with 70,000ish? miles. Previously, it sat outside in the hot Arizona sun on blocks for over five years, and became a home to several woodland creatures. After cleaning all of the grunge out of the car it started right up. Everything runs fine except the digital dash. The only thing that lights up is the "Check Engine" light.
I took the cluster and center display panel out of the car & did a visual check on the wiring harness. There doesn't seem to be any evidence of rodent damage. (There is damage to other areas, like the taillight wiring.)
Is there an easy way I can determine that the cluster itself is not faulty?
Where should I focus my efforts to find the problem if it is in the wiring?
This car is only going to be a dedicated AutoX car. It doesn't need to look pretty, but I do need some working gauges.
Thanks for any help you can provide.
Later,
BeerMan
86 Rag Top
85 Coup (#71 XP)
Melting Slicks
Joined: Jul 2003
Posts: 2,384
Likes: 124
From: Reno/Sparks Nevada
If you can see that the gauges are operating properly and they are simply not lit up then the bulbs that illuminate the cluster may be burned out. This is a common problem that with any bulb will eventually burn out. If the gauges are not working right, meaning you can't see the volts, temp, oil pressure, mph, tach, etc or they are displaying really weird alien type displays then the problem is with the cluster which can be sent out for repair. I'll post a couple of links you'll find helpful. Read Batee's columns and if you find it helpful please consider a donation to him. I'm not connected with him at all but he is generous enough let us post his links. Art...
http://www.batee.com/corvette/dcrg/repair.htm
http://www.batee.com/corvette/dcrg/lightbulb.shtml
http://www.batee.com/corvette/dcrg/repair.htm
http://www.batee.com/corvette/dcrg/lightbulb.shtml
Last edited by MrRenoman; Dec 26, 2007 at 02:15 PM.
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
If the bulbs are good...it's time to check the grounds..there are several, but first check the one on the drivers door pillar (kinda have to pull the carpeting back a little) then check the ground connections on the drivers side head...close to the firewall...hard to get at, but alot of ground connections there.
A good book to order is from Gordon Killebrew...he's the C4 guru, one of his books is on the digital dash, great book and cheap.
A good book to order is from Gordon Killebrew...he's the C4 guru, one of his books is on the digital dash, great book and cheap.
Melting Slicks
Joined: Jul 2003
Posts: 2,384
Likes: 124
From: Reno/Sparks Nevada
Here's another link...looks kind of like something of Killebrew's. The link opens a word doc. Click open...
http://rds.yahoo.com/_ylt=A0oGkm5wgv...tal%20dash.doc
Art.
http://rds.yahoo.com/_ylt=A0oGkm5wgv...tal%20dash.doc
Art.
Thread Starter
Instructor
Joined: Dec 2007
Posts: 184
Likes: 4
From: Hilliard OH
Wow, this is great info. Thanks Guys.
But............. I don't even know if I need to repair the gauge panel yet. Right now, I need to determine if there is a way I can test to see if the panel has a problem. I'm pretty clueless when it comes to electronic stuff, so I don't want to randomly put power to the connectors to see if it lights up. I just need some guidance to determine whether I should fix the gauge panel itself, or look into the wiring on the car.
What I DO know is that the panel didn't work when it was in the car. It is out of the car now.
Thanks,
BeerMan
86 Rag Top
85 Coupe (#71 XP)
But............. I don't even know if I need to repair the gauge panel yet. Right now, I need to determine if there is a way I can test to see if the panel has a problem. I'm pretty clueless when it comes to electronic stuff, so I don't want to randomly put power to the connectors to see if it lights up. I just need some guidance to determine whether I should fix the gauge panel itself, or look into the wiring on the car.
What I DO know is that the panel didn't work when it was in the car. It is out of the car now.
Thanks,
BeerMan
86 Rag Top
85 Coupe (#71 XP)
Melting Slicks
Joined: Jul 2003
Posts: 2,384
Likes: 124
From: Reno/Sparks Nevada
One good way to check it is to install it in another Vet. Without a factory service manual and some basic electrical knowledge it's going to be difficult to determine anything with the cluster on the bench.
Art
Art
Thread Starter
Instructor
Joined: Dec 2007
Posts: 184
Likes: 4
From: Hilliard OH
BeerMan
86 Rag Top
85 Coupe (#71 XP)
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
10 Things C8 Corvette Owners Hate (But Won't Tell You)
Joe Kucinski
10 Best Corvettes Coming to Barrett-Jackson Palm Beach 2026!
Brett Foote
Every Corvette Grand Sport Explained! (C2, C4, C6, C7, & C8)
Joe Kucinski
Melting Slicks
Joined: Jul 2003
Posts: 2,384
Likes: 124
From: Reno/Sparks Nevada
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
Most of the problems we run into with our digital displays are related to a bad ground, which may include the ground on the circuit board, or the wiring harness connection. I think it was jfb who has posted numerous times how he simply soldered a new gound wire to the circuit board and then ran it outside the connection to the ground wire on the other side of the connection. Think that's right, I know he's gotten a little tired of repeating it.
Thread Starter
Instructor
Joined: Dec 2007
Posts: 184
Likes: 4
From: Hilliard OH
Ok,
So I plugged my 85 display into my 86. All of the LED bars lit up continuously, with the exception of a few in the middle range of the speedometer. It also went dim for a few seconds from time to time. So I know that the display isn't completely dead. But I'm curious why everything seems to be lit up.
In looking at one of the links from www.batee.com, I wonder if this could be a problem with the "rubber conductive blocks" that connect to the bottom circuit board. But his statement makes it sound like there could be a few segments that are lit. On mine, almost ALL of the segments are lit.
Should I just take the whole thing to an electronics repair shop to have all of the contacts checked?
After I know the display works correctly, I can plug it back into the 85 & start working on the grounds.
Thanks,
BeerMan
86 Rag Top
85 Coupe (#71 XP)
So I plugged my 85 display into my 86. All of the LED bars lit up continuously, with the exception of a few in the middle range of the speedometer. It also went dim for a few seconds from time to time. So I know that the display isn't completely dead. But I'm curious why everything seems to be lit up.
In looking at one of the links from www.batee.com, I wonder if this could be a problem with the "rubber conductive blocks" that connect to the bottom circuit board. But his statement makes it sound like there could be a few segments that are lit. On mine, almost ALL of the segments are lit.
Should I just take the whole thing to an electronics repair shop to have all of the contacts checked?
After I know the display works correctly, I can plug it back into the 85 & start working on the grounds.
Thanks,
BeerMan
86 Rag Top
85 Coupe (#71 XP)
Melting Slicks
Joined: Jul 2003
Posts: 2,384
Likes: 124
From: Reno/Sparks Nevada
I don't think it's a good sign that almost all the LEDs illuminiate upon startup. I would recommend sending it to a repair facility that knows what to look for and how to work on it. Just my opinion.
Art
Art
Drifting
Joined: Nov 2005
Posts: 1,361
Likes: 0
From: Downriver Mi.
not to highjack your thread, my 85 cluster has the intermitten short,usualy works cold then goes dark with turn signals lit after warming up.the tach lights up but does not work,I removed tach filter and it did not help?I check the repair links and nothing was mentioned about tach not displaying?Everything still works except tach when it goes dark.I have looked for grounds and cleaned all that I have found still no help,Can anyone post all the locations of grounds for the cluster?This would be a big help.
Last edited by MR NICE; Dec 30, 2007 at 06:16 AM.
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
It would be a good idea to purchase a FSM (factory service manual) for your year car. You can find them used or new. It has the information on testing the wiring. None-the-less, a great tool to have when working on these cars.
Racer
Joined: Sep 2010
Posts: 325
Likes: 7
From: Princeton Jct. New Jersey
This thread is almost 7 years old but then again these cluster problems are timeless. As posted, check the 4 bulbs, ground, connector contacts, etc. Oh, and try looking at the cluster display with polarized sun glasses. The polarizing film on the LCDs burn-out if exposed to too much heat or sunshine (or just due to age). If the display is readable with the polarized lenses you can replace the film to restore the display fairly inexpensively. Also, Batees' website is a good resource for trouble shooting these displays and sells some DIY replacement parts. I believe he is also offering repair services.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
I scanned these out of my '86 FSM:
http://home.earthlink.net/~cliff_har...s/grounds.html
