Oil pressure switch

Hi all,

I've just purchased an '89 Mk1 GTi cabby, and I have a few questions about the oil pressure switch:

- When I turn the ignition on, the oil pressure LED does not light on the dash; is this normal?  Sorry for asking obvious questions, but I don't have a user manual so I don't know what to expect.
- On further investigation, it seems that one of the previous owners has disconnected the connector for the oil pressure switch (the one on the right hand side of the engine) and clamped it onto the engine block (to earth).  Any idea why anyone would do this!?  I assume that the switch failed and someone tried to bypass it.  I suppose the alternative is that there is an oil pressure problem that someone has tried to hide, although the engine appears and sounds healthy and pulls strongly with no leaks or smoke at all.
- Whether the connector is clamped to the block or not makes no difference, the LED still does not light on the dash.  Does this indicate a problem with the dash display, or just that the switch failed?  Other LEDs on the dash seem to work OK.

I've ordered replacements for both pressure switches, I'll see if replacing these make a difference.

The GTI has 2 oil pressure switches, one for low pressure (0,3) bar and one for high 1.8 bar (on the oil filter cover i think). They're working together by sticking to the ground, low is sticking to the ground when the engine is not running - but when the pressure comes it is not sticking so the oil hazard light stop blinking. High pressure switch is sticking to the ground when too high pressure comes so the oil hazard light starts blinking. Sometimes there is a special switch for oil pressure when you have extra oil pressure gauge (it looks like little bootle). And there were two models of switch for extra vdo gauge. One with the integrated oil pressure switch for hazard light in it, and one simple just for pressure measuring. Sometimes there is an one extra switch on filter cover for temperature gauge VDO. Hope it helps

sounds like a wiring fault, trace the yellow wire as best you can. check the wiring behind the fusebox as well, if its had a missmatched engine loom fitted the yellow wire may be running to a spade rather than to the fusebox as it should

Thanks.  I changed the low pressure switch (on the side of the engine), this seemed to make no difference to the oil light on the dash.  However this morning when I turned on the ignition, the oil light flashed, and then went out when the engine started.  So, could be an intermittent connection which I'll need to trace.

right good news is the wire is in the right place, just got to track down the dodgy connection

Weirdly, the oil pressure light on the dash now works in the morning but not in the afternoon!  Also, the buzzer now intermittently comes on in the dash around 2000rpm and goes off around 2500 - but only in the afternoon, and not in the morning!  Sometimes the buzzer comes on at at lower engine speeds.  I think this all points to some wiring issues in the dash, think I need to take a look and see what's going on.