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Warning lights gone

tasheido

Enthusiast
Messages
18
After the starter failiure, i had this weird problem. After fondling with some of the fuses that were making poor contact (changing them for new ones),both oil and water temperature warning lights failed to light before ignition. The battery light turns on but the other two don't. I don'n know if the problem is fuse related because all the fuses are good, and as far as i know there is only one fuse involved with the instrument panel (the 10A one to the right). I don't have the schematics for the R4 , so i started by checking if the lights were ok, and they are. I also found a diode on the panel that seemed to be involved in the warning lights part of the circuit, and the diode also tested out ok. I don't believe both sensors went out at the same time, anyway i checked if i had voltage on the temperature sensor, found 12v there, so at least it has voltage. Then i turned the car on and tried shorting the water temp. sensor and still the warning light didn't turn on. So i guess the problem might be in the fuse box because it was the last thing i messed with before i had the problem. Maibe a connection came loose inside or something, because on the outside all fuses seem to make good electrical contact, and the ones that where bad were changed. Is the sensors circuit protected by more than the panel fuse? doesen't make much sense but i don't know. I even taped a bit on the fuses and the box and still they don't turn on. So if any of you stumbled on something like this (both warning lights off before ignition) and could lend me some help, i would be very happy to hear from you!
 
All of the warning lights are fed from the same fuse - that's fuse 1 to the right of the fusebox. Also on that fuse are the foglamp and rear screen demist.

The circuit is fairly simple. Ignition --> fuse 1 --> warning bulbs --> senders. The diode just connects the temperature warning sender to the oil warning sendrer so that both come on for test when the ignition is switched on but there is no oil pressure.

If you have a voltage at the temperature sender feed (on the top of the block) then that would suggest the fuse, warning lamp bulb, and wiring is OK. Maybe if there was really high resistance in the system somewhere you would get a voltage with the tester but no current to operate the bulb.

The only other thing I can think of is if the wire to the oil pressure sender has become dislodged. Try earthing the oil pressure wire when the ignition is switched on and see what happens. Do both lights come on?

:clementi:
 
Got lights!

Dah! it was just a bad connection, but on the oil pressure sensor. I never checked that one. Some contact cleaner and i was done in less than 5 mins. Quickest repair so far! I missed the lights specialy the one that means "Your head gasket is cooked".

Thanks
 
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