DirkSx1

Instrument cluster failed on my 1989 944 turbo. All instruments on the cluster are not working, including water temp, oil pressure, fuel gauge, tach, speedometer, odometer and voltmeter. Can't close the sun roof and the air conditioning quit as well. How all this started. At 1st, the main red idiot alarm light went on and then off, then it started to flicker, and shut the car down and then all went blank. Then shut down the car again and restarted and everything worked for a little while and then all quit for good. All this happened while participating in an autocross event. Drove the car home without instrument, about 40 miles without any problems.

Car start and runs OK, lights work, cooling fans and heater fan all working including radio.

When I turned ignition on the next morning, instruments went on momentarily and then nothing again. seems strange that the instrument cluster, sun roof and air conditioning compressor are all dead.

Here is what I have done so far.

1- Re tightened battery ground
2- Have checked all of the grounds under the dash. They we clean and tight but undid and re tightened them anyways
3- Took out instrument cluster and checked connectors (all three) and all of the bulbs, lighting and warnings. None looked blown.
4- Checked instrument fuse # 18 and connector. Changed the fuse just in case and verified 12 volt power
5- Checked relay G18 per one post even though it did not seem to make sense as this is the alarm relay on US cars. Opened the relay and it looked OK.


OK guys, what do I check next? Change the G18 relay? Changes or even remove all the bulbs in the instrument cluster even though they look good. Anything else i should be checking??

ehall

bump

jc in rb

I had most of these symptoms also. instrument cluster would come and go, sun roof blah blah ect. turns out my battery cables were toast. had them changed and all is good now.

ehall

That makes sense. The aux wires to the fuse box come off of the positive cable as well.

DirkSx1

Thanks guys, will start checking the positive wire out this evening. From your comments, its not necessarily the main feed that is the problem as starter and other heavy load system seem to be working but rather the smaller aux wires. I take it one goes to the relay/fuse panel. Notwithstanding, it does not entirely make sense to me as I have confirmed there is 12 volt at the panel fuse. I presume then the problem is not so much power to the panel but power to the various sensors etc that feed the instrument panel gauges are the one not getting the required power.

Got the get this fixed soon as I have club road trip in the mountains along with an autocross event.

ehall

IIRC there are three aux wires, attached to the batt + that terminate at the fuse box. If they are original, you may have a bad wire causing the problem.

jc in rb

How old are your cables......

DirkSx1

Cables are original, car only has 50k miles on it.

I quick glance the battery end suggest they are OK but I haven't had a chance to thoroughly check them yet as I was away on business trip. I will let you know what if anything I discover this weekend. I am beginning to think, it might be the connection at the back of relay/fuse panel. Or is this bad deduction.


Must be a pain to replace them.

jc in rb

Its a pain to inspect them as they dive into the depths of the engine bay. If they are that old(regardless of miles, they prob have cracked insulation and corrosion which acts as a bunch of resistors. Mine would start and run , but did not flow enough current to run all electric systems properly.I also had the harness from the alternator changed . car runs much better now.

ehall

Might be a good time to get an iceshark kit fron Robby, with the additional positive to fuse box.

DirkSx1

Well no success so far. I checked the two power leads to the central panel, they look fine, both end are pristine with like new copper. no oxidation, the jacket on them is also in great shape.. I also undid all of the connectors at the back of the panel and they look OK as well with no loose wires.

As previously mentioned fuse 18 going to the panel checks good as well. Even if it wasn't it would not explain why the sun roof does not work anymore. Next I am going to take every fuse in and out a couple of times to make sure that there are good connections and will do the same thing with the relays. However, at this point I am at a loss as to where I should be looking next particularly given the car starts and runs well .

Is there a particular relay that could be causing this. On another post they suggested changing G18 but that is the alarm system relay and does not make sense to me but again, i don't know.. Could it be the instrument cluster itself, the resistor on the circuit board on the cluster, could they have blown.

Any other suggestions.

ehall

Well, I'm certainly no expert on electrical, but the damned relays, on these cars, always seem to have ten extra unknown functions, and changing them miraculously fixes crap that I didn't even know were broken. lol. Good luck!:-)

DirkSx1

Yes I am hoping that it is a relay. I discovered a thread on a Pelican forum which goes back to 2009 which described my exact symptoms. Their problem after pretty much what I did , where relays which don't seem to have any relevance to the instrument cluster. Subsequent readers, having done exactly what I have already did, discovered the same thread and tried its recommended relay changes with great success. They mentioned G2, G14 as the culprit and in another thread G18. Replacement relays have been ordered and will be trying those once I receive them. If will post the results once done.

DirkSx1

For reference purposes, I finally fixed the problem. As previously mentioned, what appear to be unrelated relays can be the cause of the problem. Received my replacement relays this morning, G2 and G14 where only $7 each. Replaced G2 and instantly all is well again. 2 weeks of frustration for a 1 minute fix.

If anyone has this problem in the future, try replacing the relays 1st before checking everything else. it takes a lot less time.