Oil Pressure Warning Light - 1994 Car

[Bob the Planner]

Yesterday whilst starting the car I noticed that the oil pressure warning light (red light at the bottom) failed to light on turning the ignition on. On starting the engine I got the nornal pressure indicated by the gauge so it does not appear to be a problem and I would expect the light to be on if there was.

I had a look in the bible for the location of the switch, however I could not find it. Is it the unit next to the oil filter with a single wire coming from it ? (There is a different unit slightly further aft which I believe is the oil pressure gauge sender).

The first thing I want to check is the switch as I don't want to get the dash off unless I need to !

[paulathome]

Take each wire off each sender unit and ground it on the chassis.
The oil pressure light should come on, or the gauge should go to full scale depending on
which wire goes where.
If the light does not come on, then looks like bulb has gone.
Dash off time
Hope that helps.
Cheers
Paul.

[Bob the Planner]

Do you which is which ? The unit next to the oil filter has no resistance as if it is a closed switch which points to a wire / LED failure so it may be dash off time

[Cider Andy]

The one with one wire normally drives the indicator lamp.

[Bob the Planner]

I'm only going by what the manual says. I have a red one at the top which does nothing, an orange one in the middle that goes off when I start the car and a red one at the bottom which used be on before I started the engine and now is off when the ignition is on. The manual says they should be battery, alarm and oil but gives no indication of colour.

I suppose someone might have mixed them up when the alarm was changed (I now have a bulb next to the ignition) which would sort of make sense as the top one never works (old alarm bulb ?), the amber one is a working oil pressure switch and the one that doesn't work would be the battery charging warning. Mmmmm - further investigation required I think !

[Dave 500]

My oil light is orange if that helps but its a 1997 car so might not be the same

[jason1788]

The lights on my '93 don't match the handbook, I have alarm (red/top), oil (yellow/centre) and ignition (red/bottom). Unlikely to be a bulb failure as they are LED's but if you want to change one they can be unscrewed out from the front (in theory anyway, you need to be able to grip it with something)

[Bob the Planner]

Thanks Jason.

So it lookes like the ignition light - NOT the oil pressure one. I suppose I can check by removing the lead from the oil switch and seeing if the orange light goes out too

What does the ignition light failing to come on indicate ?

[Cider Andy]

Most likely an alternator fault although it could also be a faulty connection on the back of the alternator (one of the thinnest wires).

Check the battery voltage with the engine running and stopped. It should read around 12V with the engine off and between about 14.2V and 14.8 with the engine running. If it does the alternator would appear to be working properly.

[Bob the Planner]

All the wires on tight and the light is now functioning - maybe there is a break in the wire somewhere and its now working having disturbed it a bit. 14.4 V from the (recently reconned) alternator so that looks OK.

Thanks for all the help guys.