Uil pressure light staying on

diamond · Post by **diamond** » Sun Mar 01, 2009 6:22 pm

Just redone head gasket put everything back together. Started 1st time and ran ok. Oil pressure light went out while engine was runiing. But when took key out of ignition oil light stays on. Any ideas?

Engine is a V8 in an 1985 LR90

thanks in advance

Paul

ChrisJC · Post by **ChrisJC** » Sun Mar 01, 2009 8:37 pm

Weird!!

What parts of the wiring did you have to remove?

Are any other things 'live'?, e.g. temp gauge?

Chris.

diamond · Post by **diamond** » Sun Mar 01, 2009 9:21 pm

disconnected alternator, water temp wiring to sensor, lead from distributor to engine (earth i assume)

fuel guage and water work. other dash lights seem to work ok

I assumed that as the light goes out whilst running it is doing its job and that staying on after switch off is maybe a short circuit or bad earth?

ChrisJC · Post by **ChrisJC** » Sun Mar 01, 2009 10:56 pm

The thing is that the oil pressure sender forms the earth connection on the circuit.

So +12V is fed through the ignition switch to the oil light. The other side of the oil light goes to the sender, which earths unless there's some pressure.

So to get the light on with the ignition off, the oil light must be getting a 12V supply from somewhere!!?

Or alternatively the oil pressure wire is not connected to the sender, but something that is at +12V.

Chris.

diamond · Post by **diamond** » Mon Mar 02, 2009 6:55 am

Checked oil pressure connection/wire this morning and found a break in the cable. recrimped it and it now works. dont understand it myself but it works.

thanks for advice