84 Digital Dash

[1stiff84]

Dear All,

I have read the numerous threads regarding intermittent dash display and have looked into grounds, bulbs and the terminal connections (all are OK), but can't seem to get my display to consistently light up. I do not see the directional and high beam lights that are also usually mentioned when there is no dash display.
Someone told me he had the same problem with an '85, and told me that there are lamp drivers within the cluster and I need a new cluster from GM and that this is the only fix. Is this true? If not, is there something I have missed?
Any help would be greatly appreciated.


Thanks,

1

 

[JonM]

Here is a little light reading for you...


http://www.corvettemagazine.com/1999/dec99/dash/dashp1.asp

http://www.batee.com/corvette/

 

[1stiff84]

Thanks, Jon

Jon,

I had originally read the thread that contained your attachments. I have tried the remedies described and have checked the grounds referenced in both links. All checks out OK, but still no display. Any other ideas?

Thanks Again,

1

 

[jet4rs]

Stiff,
I bought the jet with a bad display and sent it up to Michigan for repair ($300 in 95). It worked great when I got it back but now there was a fluckuation with just the insturment panel. We trouble shot a bad alternator but upon replacement the flucks were still there. The mechanic that assisted me on this little project tried an insturment panel ground. Took a 20 gauge wire and attached it to the metal housing on the back of the panel and ran it through the fire wall right to the negitive terminal of the battery. Presto Westo, it was fixed and to this day the ground wire is still there and the panel is working like a charm. The mech said there should be a factory ground already in place for the case and we could read the ground through the connector at the panel. I guess we just force the issue.

Good Luck
Bob w/jet4rs :cool

 

[rbyrne]

I was told that the 84's were particurarly troublesome because the hard stock suspensions were shaking the daylights(no pun intended) out of the display. Call "For Your Car Inc." in Cross Plains Tenn @ 1-800-398-3883 Gordon Killibrew - he publishes a digital cluster troubleshooting and repair manual that's really good. about $30. I'm sure your problem is in there and it'll save you a lot of time and guessing. Regards,

Rick

 

[jet4rs]

Rick,
The 84 has got to be better than the 63;worship

 

[1stiff84]

Thanks, jet4rs and rbyrne

Thanks much for your help and suggestions.

There's actually an e-link to the Killibrew book that was posted by JonM. Unfortunately, the suggestions in the e-book did not help my case.

I will try Bob's suggestion.

Thanks Again,

1

 

[kmcewan]

My 84 had similar problems.

The dash was blinking like a Christmas tree.

Followed instructions from Vigmann and others on disassembly and cleaning.

All I did was clean the contacts on the main connector, replace all the bulbs and reassemble. Everything worked afterwards.

Might be that simple for you.

Ken

 

[1stiff84]

Thanks, Ken

I tried that, too. Cleaned contacts and everything lit up, then a week later, no lights again.

Thanks for your reply,

1

 

[Mr Dark]

I won't cover the long story of my dash problem, but part of the fix turned out to be a short in the ground wire IN the wiring harness. So just because it looked like it was grounded properly, it really wasn't. I don't know if this could be the cause of your problem, but it's something to consider. Good luck!

 

[1stiff84]

Thanks, Mr. Dark

I checked volts through pin connectors using terminal grounds from same connector. That would rule that out, right?

Thanks Again,

1

 

[geekinavette]

Is it just illumination you're having a problem with, or is it a problem with readings also...ie does the tach, speedo...etc work normally?

Bill

 

[1stiff84]

Hi Bill

I am only having a problem w/illumination (knock on wood). All gauges work.

Thanks,

1

 

[geekinavette]

Re: Thanks, Mr. Dark

I checked volts through pin connectors using terminal grounds from same connector. That would rule that out, right?

Maybe, maybe not. There are two separate grounds to the instrument cluster, one signal ground and one illumination ground. The illumination ground is pins D1 and D2 (D3 is the signal ground). The illumination ground runs over to the passenger's side door hinge panel and connects to the chassis there. Make sure when you are checking for illumination voltages that you use pins D1 and D2 for your ground. One common cause for illumination problems is the photo-detector. I had this problem with mine, sometimes it would be bright and sometimes it would be too dim to read. I just bypassed it for now...the dash is at full brightness all the time.

If you take it apart again make sure you go over ALL of the soldered pins and look for a broken solder connection...VERY common!

If you need any wiring diagrams or pictures of ground locations let me know.

Bill

 

[geekinavette]

I won't cover the long story of my dash problem, but part of the fix turned out to be a short in the ground wire IN the wiring harness. So just because it looked like it was grounded properly, it really wasn't. I don't know if this could be the cause of your problem, but it's something to consider. Good luck!

I remember that, what a mess!

Bill

 

[1stiff84]

Thanks, Bill

I have checked D1 and D2 when checking C16 and D16. Both are OK.

Thanks Again,

1

 

[geekinavette]

Also check C9 (voltage should vary with the headlight swith dimmer) and C6.

You can see if the photodetector is the source of your problems by shorting the two leads of the detector together (of course you'll have to take the cluster apart again to do it). This will cause the cluster to operate at full brightness all the time (if everything else is working correctly).

Let us know how it turns out.

Bill