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HomeTech Articles > Solving Strange 944 Gauge Problems...

Pelican Guest Technical Article:

Solving Strange 944
Gauge Problems

Michael Van Bibber (AFJuvat)
Vanbibma@cfl.rr.com


Tech Tip: Strange Gauge Behavior in a Late (Series 2) 944.

I wrote this article after having some strange readings on my instrument cluster – to include: fuel gauge reading ¾ full when I just filled the tank, voltmeter constantly reading 12 volts.

My initial thought was a bad ground (especially for the voltmeter) and a bad fuel sending unit. However, after replacing some burnt out instrument lights, I found a fix that took care of them both – for no cost at all!!!

WARNING/DISCLAIMER: This procedure involves removing your instrument cluster and manipulating some of the electrical contacts on your gauges. If you don’t know what you are doing, or are unfamiliar with proper electronics safety (static charge etc..) DON’T DO THIS PROCEDURE! The instrument cluster is HIDEOUSLY expensive. Pelican Parts has replacement VDO Gauges, but the circuitry is a dealer only part – and they only sell it as a whole assembly – prepare to spend in the neighborhood of $1500 or more if you screw up. Of course, if you screw up, I am not responsible, you have been warned.

Tools:

24mm Socket (for steering wheel)
Phillips Screwdriver
Flathead Screwdriver
5, 6, &7 mm sockets
metal polish (Never dull works great)
alcohol wipes (or alcohol and q-tips)
Light bulbs (available from Pelican)
Personal grounding strap (Highly recommended)
Beer or other favorite tasty adult beverage


Procedure, Removal:

1.    Disconnect the negative battery cable

2.    Disconnect the fuse for the instrument panel (yes, I know, paranoid, but better safe than sorry)

3.    Remove the steering wheel

4.    Remove instrument panel trim piece

5.    Unscrew the instrument panel

6.    Carefully disconnect the three cables from the instrument panel.

7.    Remove the instrument panel from the car

8.    Take the panel and your tools to a clean, dust free area where you can sit and work.

Procedure, Instrument panel tune up:

1.    Place the panel face down on a padded surface (clean towel works well)

2.    Ground yourself using a ground strap.

3.    If you have them, now would be a good time to change out all of those instrument panel bulbs.

4.    Now, look at the back of the panel – on each side, where the combo gauges live, you see 2 black football (or rugby ball if you are in the UK) shaped objects with a brass nut in the center. Loosen these with the socket. After you have gotten the nut and washer off, lift the football shaped thing off of the circuit board. – these are the main electrical connects for the combo gauges.

5.    Clean the nut, washer, and the brass posts, as well as the threaded post sticking out of the circuit board with metal polish – then wipe down with alcohol to remove any residue.

6.    Reassemble, making sure the nut is SNUG (DO NOT OVER-TIGHTEN!!!!!)

7.    Repeat for the other footballs…..

8.    You will also see a few SILVER, FLATHEAD, screws – snug these up as well, once again, do not over-tighten.

9.    Clean the cable attachment points with alcohol

10.    In the Haynes style, installation is the reverse of removal.

Michael Van Bibber (AFJuvat)
Vanbibma@cfl.rr.com
Comments and Suggestions:
porsche man944s2Comments: hi ive a 1987 porsche 944 s2 its was running fine and battery run flat over 2 weeks replaced battery with a new 1 and none of the gauges on the dash are working do you have any ideas i have checked fuses but all seem ok is there a relay for them any where your help is appreciated
December 10, 2011
SteveComments: I have a 1986 951. The tachometer and turbo boost do not function, but almost everything else does. Everything seems to be plugged in where its supposed to be. You said you do repairs, but I'd have to send you the entire cluster, correct? Also, my odometer does not work. Understand this is a common problem. Can this be repaired?
July 12, 2011
jhlComments: The tachometer in my 1986 944 Turbo now pegs out past the red line when started. All of the other gauges appear to work correctly. Any suggestions to this symptoms are greatly appreciated.
June 20, 2011
BURTComments: I HAVE A 1990 944S2 THE ODOMETER STOPPED WORKING, IS THAT A BIG JOB ,THAT'S THE ONLY THAT DON'T WORK
April 22, 2011
BrianComments: I have an issue where I have a 7.5 amp fuse in the circuit for the passenger headlight/fog light. I replace the fuse and turn the light on and it works. When I turn the lights off and later turn it on again, the fuse blows. I have replaced several with higher amp fuses just to guess how much current I am actually drawing. So far, I have blown fuses up to 25 amps. Any suggestions orhter than a complete rewire from the fuse panel to the light?
March 23, 2011
 Followup from the Pelican Staff: I'm guessing that you have some type of short in your headlamp switch. I have seen this many times before on other cars I have owned, although not exactly in this pattern. I would replace the switch and see if the problem disappears. - Wayne at Pelican Parts
scooter471Comments: 1988 944 s. Odometer and tripmeter not moving. The rest of the dash seems fine. Speedometer, fuel gauge, tach, oil, voltmeter all fine. ?? get it rebuilt??
October 17, 2010
CraigComments: I own a 1991 944 S2 Cab. The fuel gauge is not working it is all the way down. My mechanic changed a A/C relay and it seemed to quit working maybe a coinsidence however it is not working now. The yeloow reserve light comes on that is the only way I know to fill up Can you help? Craig
October 14, 2010
 Followup from the Pelican Staff: He probably bumped the connection to the gas tank level sensor. I would check the top of the tank and look at the sensor and/or simply take it back to him and ask him to replug it in. - Wayne at Pelican Parts
Porsche LoyalistComments: Ok thanks, where exactly are those connections I should be checking, are they directly behind the dash itself or under the hood as well?
August 22, 2010
 Followup from the Pelican Staff: Should be right behind the dash, but the problem is most likely with the gauge itself... - Wayne at Pelican Parts
Porsche LoyalistComments: I own a 1986 944 and my tachometer no longer works, whats the problem?
August 22, 2010
 Followup from the Pelican Staff: I would check the connections to the gauge, and/or the gauge itself. If you can find a replacement unit to plug in to test, that would be ideal. It's most likely the gauge itself. In some cases, these can be rebuild (we do this too), for about $150-$200. - Wayne at Pelican Parts
jzrasmussonComments: I have a 1987 944, the shift light and the MPG gauge seem to only work when the car is cold early morning. If you drive it long enough or turn off the engine after it's been a few minutes the shift light and the MPG gauge stop working again. I know these gauges are pretty much useless in general but it drives me nuts that I can figure out why they only work on really cold mornings. Any suggestions? Thanks!!
August 9, 2010
 Followup from the Pelican Staff: Hmm, the only thing I can think of is that there's a wiring connection that is becoming loosened when the car heats up. I've seen this sometimes on older cars. - Wayne at Pelican Parts
Surfman1124Comments: Got a 1985.5 Late NA Porsche 944. The Tach will run fine some times, but it will go up about 2,000 RPM over what I am running. If the car is running about 3,000 RPM, it reads 5,000 RPM. The car runs great, but it is kinda annoying. Any ideas?
May 28, 2010
 Followup from the Pelican Staff: The only suggestion I have is to have the tach removed and tested to see if it's broken or not. Or buy a used one on eBay for $10 or so, and see if it works more reliably? It sounds like an issue with the tach itself. - Wayne at Pelican Parts
TomComments: Have a 85 1/2 944. Speedometer and odometer don't move. Just replaced the whole instrument cluster and still no fix. Any suggestions?
April 19, 2010
porsche4lifeComments: http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/513424-dismantling-gauge-cluster.html
I took a cluster apart and posted in the forums... Go check it out....
November 28, 2009
jjComments: I try to restart my 1986 944 none turbo had been park in my garage for 6 months but, it does not cranking up at all. Can any body help for any possibility problems to fix it. Thank you so much
November 10, 2009
 Followup from the Pelican Staff: Sounds like a dead battery, I would try putting a battery charger on it and seeing if that helps? - Wayne at Pelican Parts
paulComments: i have a 1986 944 porsche. the speedometer needle goes up to about 20mph then stops regestering. can you give me any hints? thanks paul
November 10, 2009
 Followup from the Pelican Staff: Not off the top of my head. My only real recommendation is to pull it and have it rebuilt. Or find a good used one on eBay? - Wayne at Pelican Parts
mattComments: My needle doesn't move either. I let the gas pump automatically and ended up overflowing the tank. Is it the same problem?
October 7, 2009
 Followup from the Pelican Staff: There are multiple problems if the tank is overflowing. If your needle is not working then you probably have a defective gauge sender. - Wayne at Pelican Parts
BruceComments: Thanks so much for the info on the S2 with the airbag.
October 3, 2009
BruceComments: I have a 1990 944S2 and the speed gauge connection seems to be loose as it shows the speed but then suddenly can drop to zero.There is an airbag on the car.How to remove the steering wheel when there is an airbag?
Thanks for the info that you have provided,and for taking the time to type and post it!
October 1, 2009
 Followup from the Pelican Staff: The airbag is attached with two bolts from the rear of the steering wheel. I believe it's similar to the Boxster and BMW 3-Series - check those articles for more detail. The speed sensor is located on the transmission I believe on the S2 - check the connection, and/or replace the sensor. - Wayne at Pelican Parts
DRAWLIComments: THANK YOU FOR THE INFO
August 2, 2009

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