abcorsi

So my 89 944 S2 is having [what appears to be] some mysterious electrical issue(s). I've seen some good comments for point problems on this forum, but starting to think they might be connect going through perhaps a main circuit. Here's the situation:

1. The fuel tank was only registering 3/4 Full (even after filling) and stayed there until it dropped below 1/2 and then seemed to be accurate. I had my shop replace it, but it is still acting the same.
2. My father recently had the "you left your lights on" warning sensor replaced, but it doesn't work again
3. The cruise control doesn't work
4. The oil light just popped on, I checked the oil level and it's fine, and not a drip of oil anywhere - thinking it is the low oil pressure warning

Some of this issues may be connected, and some might be independent, but I have seen a few posts on the fuel gauge reading issue and the check oil light. Anybody have any insights in terms of what it could be and/or how much the repairs cost? Thanks!,

Zirconocene

The first place to start is with all the grounds on the car: have you cleaned every single one of them? I don't have a link handy, but there are schematics available. You want to go through and scuff sand every ground connection to make sure that you're getting good contact. While you're there inspect the ground wires themselves to look for oxidation. If you can see a little bit of green on the end, it may have traveled up the wire a bit, under the sheathing, and not be visible. Try adding a little bit of DeOxit both to the connection point (prior to re-connection) and on the exposed wire.

Start with that and see if things improve.

Good luck

abcorsi

I'll give it a try, thanks!

Niku

I've also got a similar issue with my fuel gauge and just came across this great video about cleaning the sender. It's for an early NA, so you'll want to do some more research about your car specifically.

When you say you had 'it' replaced do you mean just the gauge, because if so the sender might still be your issue and it seems like a fairly common problem, and pretty cheap to fix.

Zirconocene

Ed Redas has lots of great content for these cars, that's a good call.

abcorsi

Thanks everyone, I checked all the grounds that I could find, but the car has been extremely well cared for and always in a garage, so the grounds I can find all look pretty pristine and there is zero oxidation. I took her out yesterday, and the oil pressure gauge was frozen at 5 for the duration and the voltage appeared frozen too. But then after a few bumps on the road, the oil pressure gauge broke free and started functioning correctly. But I'm thinking it's less a Fuel Sensor or Sending Unit, and more electronics issue. So I'm going to explore to see if I can find a specific ground for the Dash, but I'm pretty sure it's this - which I found the solution on Pelican. https://www.pelicanparts.com/techart...e_problems.htm

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 1/2 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

abcorsi

Just an update, I got my shop to do the procedure the Pelican article had in terms of cleaning all the dash leads, and it worked like a charm and fixed all the issues. Now the oil pressure gauge works correctly, the check oil light no longer lights up, and the fuel gauge reads correctly. Thanks to the creator of that article, that was a great find and time & money saver on my end!