ROG100

Hi,
I am in the process of troubleshooting an intermittent problem on my 93 GTS instrument cluster.
I lose all gauges apart from the volt meter. The digital readout goes as well and leaves an orange glow.
Most of the warning lights continue to work and the "check engine" light flashes. The cruise also stops working.
The problem usually happens under hard acceleration and can be sometimes rectified by hitting the kickdown again (power surge??) - not every time though.
Connecting disconnecting the battery used to work but does not anymore. Its getting hot here in TX and that could be a factor.
I started by checking all fuses, relays and then disassembled all grounds, cleaned and reconnected them.
Fitted a new ignition switch.
The PCB at the back of the cluster appears to be OK though I did clean some residue of some of the soldered points.
I have the cluster connected in the space where the pod sits and have wiggled all connectors I can find with no change.

1) Before I replace the PCB ($1000) I would like to ensure that all the 4 connectors on the back of the cluster are working. Most of the gauges get their signal from connector #4 and I need to know it works as far as that point.
I would like to check each connection to ensure the signal is being received - how can I do this? This will pinpoint the PCB as the problem if all the connectors are OK. I have all the wiring diagrams and know each pins source. I am a little "electrically challenged" so help at this point would be gratefully received.

2) Anyone have an instrument cluster/PCB for sale?

Any thoughts would be useful.
Roger

fst951

Hi

The car's instrument cluster also gets power from the interiror light circuit as I recall. You may want to make sure that the interior light fuse is in perfect working order and that it isn't corroded. I would also check and make certain that all the interior light bulbs are in good working order. I found a shorted wire in one of my cars that kept the digital dash from working well. The alternator charging circuit worked on mine as well. I found my short behind the passenger's side quarter cover.

Good luck!

worf928

Yes it does. And I was about to write the same thing. The described symptoms are almost exactly what happens to the cluster then the interior light circuit's fuse blows.

Check the front dome light. There is very little space between the fixture's spade connectors and the roof. And if one hits the other...

The rear dome light is probably just as tight too.

ROG100

Thanks for the replies.
The lights are all fine. I replaced the overhead ones (back and front) just to be safe. The fuses are all new and fine - no corrosion either - I also bent them and pushed them in and out a few times on every one to be sure.

How can I check the connectors?

Where does the speedo pick up its signal. I know it comes from the ABS sensor on the left rear wheel. At what point does it link in to the ABS system?

Thanks,
Roger

jamesld

I had a similar situation in my car and I found that the lug wrench in the rear panel was making contact with the rear hatch switch on hard turns or acceleration. I reseated the lug wrench and put shrink tape over the rear hatch switch connectors.

ROG100

Yes I tried that - after I read one of your previous posts - it couldn't be that easy for me!!

ROG100

Just to finish this thread off!

Managed to check all the panel connections in each of the four connectors by using an ohmmeter. All tested good. So I knew all signals were getting to the dash.

Checked the PCBs under a magnifying glass but could not see anything that indicated a failed component or bad joint.

I had considered a dry joint somewhere on the two PCBs and had noticed the problem occurred less frequently in the winter. However when the hot Texas weather came around the loss of instruments became nearly permanent.

Talked with some PCB experts and they confirmed that a dry joint could be effected by expansion and contraction. There was a liquid spray that could be put on the pcb to emulate the cold condition. I did not fancy spraying the boards with liquid so I placed it in the freezer for 20mins.
Success - after reconnecting the panel the instruments worked perfectly. An hour later when they warmed up again it failed. Back in the freezer and problem solved.

New PCB board from Porsche $1000 ouch and problem has gone away.

Hope this helps someone in the future.
Roger

Alan

Roger,
Congrats that its finally solved - I know this has been going on a while - but ouch! expensive way to go huh? At least you didn't spring for the replacement PCB and find that it wasn't that after all...

Hows the remote entry? got the lights & horn/panic hooked up yet ?

Alan

ROG100

Hi Alan,
Thanks for the kind words - however I solved one problem only to find another.
The speedo stopped working for no apparent reason, I can only think that I screwed up while stripping the cluster down.
I have another thread going if you want to follow my woes.

I will get back to other goodies once I have killed the pod gremlins for good!!

Remote entry is the best part of the car at the moment.

How are your front end mods going.

Best,
Roger

Alan

Roger,
All done - $4300 ouch but it looks better than it ever has since I've had it. Everything was done in a top notch way - factory all the way.
This included fixing the bent front poiler & supports

Looks beautiful again !

I'm happy except to see the insurance premiums go up (not yet...)

Alan

ROG100

Pictures Pictures please

ROG100

Just to finish this thread off for future use by someone.

Came to the conclusion that the speedo was the culprit. However it cannot be repaired. No one who specilizes in VDO will touch it or the digital cluster as a whole.
I had an option to replace one of the gauges from another cluster - however you run the risk of breaking the shaft as you take of the needle to release the gauge. To risky!

I checked all the wiring links and was finally checking the cruise for a speedo signal when I decided to check the FCU relay again (XIX). I stripped it down did a visual and found nothing wrong with it. Assembled the relay and placed it back in the board and guess what - the speedo worked.

I have now assembled everything back together and things are fine again.

Thanks to Borland and others who have helped me kill this GREMLIN!!!!

Thanks to Jim at 928Int - what a great company!!