Sorry to have to post. None of the other posts were specific enough (and of course I am in denial that I may need to pull the cluster out again LOL).

So here it is. 1987 L98. Less than a year ago, I replaced a sunburnt LCD panel and while I was at it, replaced all the bulbs figuring since the cluster was out, might as well make use of the time. My LCD's are working great as were the backlights - until tonight! The LCD's work great still - read speed, RPM, everything they are supposed to - just can't see the darn things. I have a hard time believing that all the lights went out at the same time after such a recent replacement. I replaced both the "LCD" and "Cluster" fuses just in case and no change. The one weird thing is this: both the turn signal symbols and the high beam signal seem to be lit up. Not super birght but they are lit up.

Anyone had an experience like this or any useful words? Like I said, cant see ALL the bulbs for the LCD panel going out at the same time especially within a few months of changing them and both fuses are good so could use some help on this one. I perused the post searching the forum and see a few posts where lights went out but most either sounded like old lights or didn't specify changed recently like my situation.

As usual, came to the greatest group of folks always willing to help - you guys!

 

I would bet if all the bulbs are out or dim the power supply is failing. PM me if you want the name of a co. that repaired mine.

 

Thanks for offering the info pkazsr. I sent you a PM to get the information just in case that is the culprit.

On a side note, I found some repair guidelines from corvette magazine that had almost word for word the symptoms I am seeing and suggested it was a bad ground running from D3 on the large cluster connector. In the article, it says "One of the most common problems is the dash lights will go dim and the high beam and turn signal lights come on. When the dash lights are inoperative and the high beam and directional indicators come on dim, look for a bad ground. The most common problem is a poor dash ground on the 153 circuit. This is a black/white striped wire in cavity D3 of the large connector (Fig. 1) to the cluster. This wire goes to an ambient over-ride sensor (Fig. 3), then to the bulkhead connector to cavity B1 to the engine harness wire to the left rear of the engine."

Does this sound right or do you guys think it is more likely the power supply? If this might be it, any suggestions on what might be the best way to clean up the ground problem and fix this?

 

That's exactly what it is. A bad ground. Fix it yourself for free and that should do it. Since you've had it apart once, one more time won't hurt.

Read this and it should tell you what you need to know.

Batee.com

This should be required reading for any 84-89 owner.

 

Greetings,

I have a 1985. I took the instrument cluster out and sent it for the necessary repairs including the power source. My dash lights work whenever they please. I have noticed when its raining, the entire dash will black out, then re-appear. I have tried to address this issue with a well-known mechanic and he tells me he can't find anything wrong. He said, "There are houses with strange occurences; I think your car is like one of those houses". Now come on, there has to be an explaination for this.

Lori

 

Greetings,

Very cool link. I think I will show this to the mechanic that told me the BAD HABT is haunted. LOL

Lori

 

You have to completely disassemble the dash, most mechanics will not want to touch it. You may be able to get them to take the panel out, and then you may need to take it to someone who is more comfortable with electronics (although the electronics in those old dashes are somewhat crude). But all it takes is simple soldering. It's actually straightforward, once you're in there.

 

Going out right now to pull the dash. Fortunately I am very good at electronics and am comfortable working my way around the cluster. Replaced the bulbs and LCD for speed before so not too worried. The BATEE is a great resource - Thank you for posting that!! Will go step by step taking my time to make sure to fix the solder joints properly so I don't have to do this again.

On a different note, really starting to looking at replacing with high quality guage package instead of Atari dash. Found a good link at corvette magazine and it seems pretty darn simple - just a little work intensive.

Thanks for all the good advice.

 

Do not know if it is the same problem. I have a 91 and the dash lights would go out every now and then. I found my problem was the light dimmer switch. Once replaced no more problems.

 

I believe the dash itself it relatively reliable, once the grounding problem is resolved. I also updated the ground down by the clutch side. I can't remember if that's noted on Batee or I found that somewhere else.

Bonus points to you if you document your work and add it to the Tech Tips. I would but I don't have the digital dash (at least not that one) anymore.

 

Well, turns out it may not be a ground problem. Spent quite some time working on the boards. Found some cold solder joints, fixed those but still no luck. Spent some time re-working the ground. Ran it to the ground near the door but still no luck. Sounding like it is the power supply. Anyone know where to get a new power supply board for this? I don't really want to have to send the unit out to have it fixed since I am very adept at electronics.

Thanks to all who posted. I have some pictures that I will post once I have a chance.

 

I may be late to this game but I'll still put my money on a bad ground. These plastic tubs can do some strange things with grounds.

 

Keep after the grounds. I eventually soldered new wires to the connectors near the cluster and ran them out to the frame.
One other area you might want to check is the wires connecting the power supply to the main pcb. I found a couple on mine that were broken.

 

The power supply doesn't have a thing to do with the backlight 882 bulbs! If you have an open ground, your high beam and turn signal indicators will stay on because the ground current for the cluster goes through them because they have their own separate ground. The back lights get their power through both the 10A tail fuse and the 3A inst fuse, but then so do the wiper light, telltale, map light, radio, heater a/c control, and auto gear shift, do they go out? First check the fuse clips to see if they are bright and making good connection to the fuse, use some contact cleaner on them even if bright. Unplug the two connectors going to the cluster and wipe the board fingers with contact cleaner. DO NOT use any kind of abrasive on the board fingers! Power to the lamps also goes through the dash dimmer (also to all the instruments mentioned above) and the dimmer may be intermittent, also unplug the light switch and use contact cleaner on it too. If the dash dimmer is at fault, you won't have 12v on the green wire from the light switch to the fuse block. If only the dash back lights go out, then see if there is power on the grey wire going to C9 on the cluster connector. If it has 12v, then the trouble is with either the cluster connector connection or inside the cluster.
The ground for the instrument cluster comes out of D1 (black) on the cluster to a large splice in the cable (S213) which grounds almost all dash components that run on 12v and is behind the instrument panel on the left side. You will have to cut through the wrapping. If you have the electrical diagnosis manual, look at page 201-10A, it shows where S213 is. You can also use a sharp needle or voltmeter test prod and measure the voltage on wire D1. If lamps are out and you read 12v on D1, you have an open ground. It is safe to splice into D1 and ground it.