Annoying electrical fault

[SootySport 23]

Have a 1990 1.6gti.   The ignition and oil warning lamps in the Instrument panel have stopped working,  when key is turned to ignition on.  They were ok a week ago and engine started and ran ok.  
I have the Haynes wiring diagrams to hand and managed to fix all the lights, wipers and washers but now I’m stumped on this problem so what do these two warning lights have in common?  The cluster background illumination bulbs all work and the engine starts but won’t run longer than a couple of seconds.  
Any ideas, Bernie.

[Telf 222 2 Cars]

wiggle the key in the ignition barrel, maybe its a worn ignition? 

 

thats a guess btw but i've had a worn barrel that caused everything to randomly turn on/off/flicker. car wouldn't run either or just cut out

[SootySport 23]

Thanks Telf, I’ll check that out.

[SootySport 23]

Not the ignition switch I’m afraid. Anyone know where the ‘oil indicator unit” is?

[Telf 222 2 Cars]

the oil pressure lamp is put on by the oil px switch on the front of the block next to the pressure transducer . Next to the oil filter.

[SootySport 23]

4 hours ago, Telf said:

the oil pressure lamp is put on by the oil px switch on the front of the block next to the pressure transducer . Next to the oil filter.

According to the wiring diagram, the oil pressure sensor and oil level indicator go through an oil indicator unit which control the warning lights.  That’s what the Haynes manual diagrams show but are they right or are the diagrams for for a later model? My engine code is XU5JA.

[Tom Fenton 1,524]

Oil level indicator is a sensor in the back of the block, but I've never seen one in use on an 8v engine. The 16v's Mi16 etc usually have them. Not sure what wiring diagram you have but it doesn't sound right for a 205 GTI.

[Ryan 99]

The very early 1.6 GTIs had an oil level sensor. It was wired through an adaptor box that converted one of the other gauges into an oil level gauge for a few seconds when the ignition was switched off. I think they stopped fitting it after about 1986.

 

Some of the info in the Haynes manual only applies to the early models, so it might include the wiring diagram.

Edited November 20, 2020 by Ryan

[SootySport 23]

On 11/20/2020 at 10:34 AM, Ryan said:

The very early 1.6 GTIs had an oil level sensor. It was wired through an adaptor box that converted one of the other gauges into an oil level gauge for a few seconds when the ignition was switched off. I think they stopped fitting it after about 1986.

 

Some of the info in the Haynes manual only applies to the early models, so it might include the wiring diagram.

Ive already found out the diagrams are not 100per cent accurate for all years.  Have the pressure sensor on the front of block and the oil pressure gauage works ok. The oil level sensor fitted in the rear of the sump so I guess that operates the dash oil light.

I'll be back in the problem in a couple of days and I'll ground the sensor wire and see if the dash light lights up.

As for ignition light,  when engine running I see 12v coming from the alternator with the exciter wire disconnected and 12v coming from the dash light which is correct but the ignition light never lights in either ignition key position.  Battery charges ok at 14.3v.   All very strange and I'm wondering if a loom has been squashed somewhere under the dash when I fixed the clock and radio.

[Tom Fenton 1,524]

Pressure sensor for the gauge is in the front of the block near the alternator. Next to it is the pressure switch that turns the light on and off. In the bottom of the sump is the temperature sensor that does the temperature gauge. The oil level sensor is not usually fitted but lives in the block not sump.

[SootySport 23]

Ok Tom,   That’s cleared up which one does what, thanks.

[SootySport 23]

Mystery solved,  all the sensors are ok and alternator was tested ok.  It was just some of the instrument panel lamps that had popped or had bad contact with the printed cct. film, a bag of bulbs, holders and cleaning the printed cct. Fixed the problem, easy in the end.