Earth issue? dull oil light random when driving

[Shinnster]

Hi all,

i'm having an issue that i think is the earth from the oil pressure switch but just looking for confirmation really that nothing major is wrong!

I had an issue with the buzzer and oil light going off (even though my pressure gauge reads ok when it happens)
i had diagnosed it as  a faulty switch / sender , the one below the water pump on 1.9 DG.  I am unable to get any of my sockets in that gap to get the thing out, so as a temp fix i removed the wire and put it onto the left side of the engine with another earth .

Now though, when i'm driving, at completely random times, it could be after 5 minutes, or 2 hours into a journey the oil light comes on really dull for about 6 - 8 seconds, then switches to the battery light for a split second then goes away.

so is this just me and ive done a dodgy attempt at earthing it? (which i'm guessing is the answer as it was fine before i done it) it was all cleaned up before i done so .
Any tips on getting the sender thing out ? as i'd rather just have it back to how its meant to be

[maxstu]

Check the dash multipin is fully seated.
Check the oil switch wiring back to the yellow connector for damage.
Release the three bolts on the waterpump pulley. Slacken alternator belt and remove waterpump pulley.
This will give better access to switch.
Remove switch and test.

[Shinnster]

thanks for the reply,
the dashboard plug is in fine, i also have the upgraded dash thing and no longer have the blue ribbon thing.
the wiring back to the yellow connector doesnt look too bad, a bit grimy but nothing major

i did have the waterpump pulley off when trying to get to the switch, but i couldnt get my socket in to seat on the nut properly, it seemed to have to go at an angle and something stopped it going all the way on.

i'll try again at the weekend and see if i can replace the older wire going back to the yellow connector too

[tobydog]

Try a box spanner for the switch

[davidoft1]

If the switch is factory there’s a small zip tie that make it difficult to get a socket on the switch, I would give the dash plug a wiggle

[mioba]

Check again the ribbon on the multi-pin connector. They wear the copper foil.
Easy but fiddly repair with silver conductive paint.

[Aidan]

I would also advise checking the alternator support bracket, when they fail the earth for the alternator becomes dodgy, they have a tendency to crack where the two distinct pieces of metal that make up the bracket join together and also sometimes break the studs that hold them in place; symptoms often starts as a dim flicker of the charge lamp only noticeable at night in my experience but could be related to your issue, so worth a good eyeballing