Elektrik: Tankanzeige

[Beumers]

Hi all

I've got this fuel gauge that is not working. When I turn the ignitionkey the orange low fuel level light works in check control mode. In the self diagnostic sequense everything works also the fuel gauge.
I checked the contacts on the fueltank with a multimeter and the measurements seem close enough to be right. The fact that I get a reading from the mm is reason enough to believe that the sensor in the tank is in working condition. The signal does not reach the gauge in the dash, At least that is my conclusion.
2 questions.
1 Could a defective capasitor on the electrical print in the instument cluster be the cause of this problem. I read that there are 5 of them and they seem to be the cause of a array of problems.
2 Does anybody has a diagram of the pins of the plugs that go in the back of the instument cluster, so I can see what pins are responsible for the fuel gauge. I've got the model with the blue backcover. I think it's a '92 model.
You don't have to reply in English. I fluently speak and read German but I stink in writing. Takes me to mutch time.

Gruss Henk

thanks again for the help last summer. My climate control is working like new again.

[Erich]

pinout is here
 Steckerbelegung Kombi

[Setech]

Zuerst mal prüfen, ob der Sensor wirklich funktioniert, kann man ja testen, indem man die Widerstand misst und dann einmal 5l Kraftstoff in den Tank füllt, der Widerstand sollte sich ändern.

Der graue Stecker am Instrument ist dein Freund. Farbe für den Füllstand ist braun/violett die Reservelampe ist schwarz/rot/gelb. Dort kannst Du auch messen.
Schaue dir den Stecker genau an, Korrosion ist nicht selten.
Wenn bis dahin alles i.O. ist, kann es eigentlich nur am Instrument selber liegen.
Die Kondensatoren der Stromversorgung altern und sind sehr häufig eine Ursache, aber das weißt Du ja schon.

Halte uns auf den laufenden.

[Beumers]

Thank you both Erich und Setech.
That is all I needed to know. I can now go on being sure what I'm doing.
The link in your post holds a lot of infomation. I wil be using this for many other jobs to come. Thanks Erich.
If the fuel gage will work again, I have fixed everything that did'nt work when I bouth this car some year ago.
I owned a 730iA (1991) for 11 years. Great car, but the one I own now is already in a better state even though it is 5 years older.

The only dark cloud on the horizon is the intention of the Dutch gouvernment to change the tax law by which we don't pay taxes for cars older than 25 years of age. Taxes and fuel are quiet high in Holland and alot of classic car owners will be forced to sell there car. Most of them invested a lot of money in them and they'll never get it back. Nobody will buy these cars anymore.

But in the meantime I'll try to spend some time by repairing the fuel gauge.

Thank you. I'll keep you posted.

[Beumers]

Hi
Today I checked the wires from the tank to the instrument cluster for continuity. The wire for the reserve lightbulb is oké. Full continuity. The one for the gauge keeps going up and down between 1100 and 1800 on 2000kohm and than drops to no reading. Open circuit. Disconnect / reconnect and the whole thing repeats itself. Have to figure out what that means.

Keep you posted. Henk.

[Beumers]

Today I bypassed the wire that runs from the tank to the fuel gauge. I was almost convinced that this would do the trick, But no. No banana's today. Fuel gauge persisted in it's silent mode, but the service interval display had every led burning so all green and orange leds where lit but also all the service indicaters. When I took the wire out and readjusted everything, all was well again. one green led.
I'm a bit puzzeled now. I have to rethink the matter. I noticed that the wire for the fuel gauge had a different color than it should have according to the manual. It was brown/green instead of brown/violet. But than I also noticed some sort of greace on the wires within the rubber cover. The violet could turned to green by that. I have to see where the wire shows up in the interior to find out.
Is it possible the instrument clusters have a different pin layout. It seems not likely because everything else functions just fine....
I should have the first version with the grey backcover. In the past it's replaced with the one with the blue backcover.(92) It's the 3rth and final version.

Keep you posted. Henk

[Beumers]

I noticed that I checked the wrong wire. Somehow I misread the wire numbers.
Now I have full Continuatie on both wires, so I'm convinced that the Elko's are faulty.
Have to find the parts and the time to do the job.

Keep you posted Henk.