bspvette

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)

MrRenoman

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

rick lambert

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.

MrRenoman

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.

bspvette

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)

MrRenoman

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

bspvette

Does it need to be another 85, or is my 86 close enough?

BeerMan
86 Rag Top
85 Coupe (#71 XP)

rick lambert

Just plug it in...you ain't gonna hurt anything.

MrRenoman

I agree. I think the clusters differ in the way they angle in the dash and the way they are attached, otherwise like Rick said...just plug it in.

bspvette

Thanks Guys. I actually hope it is bad, because I really don't want to get into all the wire harness junk.

rick lambert

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.

bspvette

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)

MrRenoman

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

pmihaltian

Contemporary Corvette will service and repair your dash unit for about $200. Give them a call and see if you can work out a deal.

MR NICE

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.

RRT vette

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.

MR NICE

I have 1,it shows the wiring dia. but does not show the locations on the car.

wescarver54

Like others my cluster does not light up except for the turn signal indicator and high beam indicator. Even the odometer is not registering. Any advice there.Thanks.

fredd1

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.

Cliff Harris

The grounds are shown in the back of the electrical section 8A.

I scanned these out of my '86 FSM:

http://home.earthlink.net/~cliff_har...s/grounds.html