Hi guys, we have an '84 Berlinetta "Starship" version with the digital cluster. It started giving us problems at the end of last season. Driving one day, working fine, then poof: some smoke, burned plastic smell and no more of the blue/green digital display from the 80's. Everything else is working fine. I took it over to the electronics guys and he cleaned up the board and replaced the transistor that controls the display with a similar type transistor. He is very reluctant to run current through it because this isn't his specialty and he doesn't want to make the matter worse. So, I plug it up and WOW -- works fine, for about a minute, then dies out again. After about 30 seconds or so, the pattern gets distorted and then just dies out not long after. It has done the same thing like 2 or 3 more times (with the only difference being no smoke or burned smell). We were wondering if anyone has any experience in this area. Also, we were suspecting that maybe the dim switch or somethuing from the headlight control pod was sending a current spike or something like that. Any help would be appreciated. Thank You.

 

Did a previous owner put too large a fuse in for the gauges? Checking that might save you the trouble of taking your cluster in and out every time. Still wouldn't explain the spike though.

Does it go out when the car is running or will it do it just on battery power? If it's running then you should have the alternator checked, maybe it's sending the spike.

 

Thanks for the reply. Good thinking! A past owner didn't estimate the fuse box cover to be of any value to this car, so I'll have to look around at which fuse controls the digital display and what amperage it should have. Then, I'll look into the alternator. We didn't try to light the display without running the car. But we will the next time, for sure. Any other ideas up your sleeve? Thanks

 

Nope, I don’t have any experience with the digital gauges so that’s all I got 🤷‍♂️

 

ping JohninRI he has more experience with these

 

Thank you, Gents!

 

I took the alternator over to the shop today. It tested fine. They mentioned that checking the wires around the alternator, between it and the battery. Seems if one of those is not working the alternator will over charge. So, that'll be my next step. If anyone has any ideas, please, shoot!

 

Would someone who knows John In RI please ask him to chime in on this thread? I've been reading his prior replies and WOW! he knows his stuff. I would really need to speak to him. Thansk in advance guys.

 

https://www.thirdgen.org/forums/member.php?u=884 try sending a PM, or tag him in the thread... @John in RI

 

Ok, so far I have:
had the alternator checked - it works fine.
have checked the fuses - all are fine.
Removed the entire dash, and then:
had the yellow VSS module checked - it is fine.
had the light module checked - it also seems fine.
Yesterday, I noticed that there is a light green wire on the VSS module that had been directly spliced into a yellow wire on the Speed Control Module (Cruise Control Module). I wanted to find out what had been done by prior people here, so I traced the wire along its route...It leads to a female, single-wire grey pigtail that sits on the top part of the dash area (just below the dash pad), about mid-car so just below below the rear view mirror. I looked around for the other part hidden away and sure enough I found the male counter-part with a yellow wire that leads back to the Speed Control Module. So the questions are: why were they unplugged and why would GM make about 8 feet of wiring, go halfway aroung the inside of the car inorder to connect two, side-by-side modules???? And, even more importantly, does the length of the wire serve a purpose of slowing down the signal? Could a shorter wire screw up the signal somewhat? Maybe someone prior worked in here, forgot them and decided splicing was the easier, quicker route. I will continue checking around. Post back later. If anyone has any ideas, I'm a big fan of those, please share them.

 

Today, I worked on a lot of crappy grounding points. Some were missing, some were rusty and some were dangly. Now everything is nice and clean and reading a solid 14.4V. Tomorrow, I should be able to get the cluster back in and fire it up.

 

I sent him a PM but I don't know how to tag him...

 

Well, I have some very good news...We fixed it. It seems that my electronics guy, who was hesitant to run live current through the cluster, finally got the gumption to do so and realized that the transistor that he had been using was putting out heat as soon as it would get current and then a minute or so later would just fizzle out. So he tried another type of transistor and this new one doesn't heat up at all, it worked for hours on end. So, we saved an 80's digital dash here...One for the books. Thanks guys!

 

I know this post is a few years old now, but do you happen to know which transistor they replaced? I have two spare clusters, one dead and one working, and I'd be willing to replace a transistor if I could resurrect one of the dead ones. The cluster I'm using is starting to have occasional dimming at the bottom, and the tach meter jumps around at times, so having two working spares would be better than one.

 

Hi, sorry but I don't have any info on which one was weak. I found bad solder joints/circuits on car clusters by removing the plastic casing, plugging the cluster in and using the eraser end of a pencil to push the chips....when you see your graphics change because of the pressure of the eraser, you'll have found the pesky culprit. Hope that helps, good luck!