Oil Pressure

[ss083]

Hi All,

I have a problem with my oil pressure gauge.

When I switch the ignition on the car but dont start the engine, the pressure
on the gauge states 30 psi, should this be zero.

If so, could the problem be a bad earth, again if so, how can I test and rectify?

Cheers.

Steve

[mikey]

Steve
It should definately be zero. I presume its an electric gauge? if so Wilf's one of the electrical geniuses around here. However it's Sunday and he always wants his weekly nooky up till about 2.00 pm followed by bacon and eggs, so be patient and you will get a response.
Mike.

[normanh]

HI,

Are you using the correct sender unit....most electrical sender units vary resistance as the pressure goes up, so allowing more movement in the needle.

Dont beleive its a dodgy earth (except see below)as the gauge has 12v on one side all the time and is earthed through the sender unit.

Try disconnecting the wire from the sender and see what happens, it should go to zero when the wire is floating, and all the way across when touched to earth.

If you gauge still says 30, disconnect the wire from the rear of the gauge and try again, if its still reading then it would point to the gauge.

If removing the wire from the sender shows the correct response then try replacing your sender, if the removal of the wire from the gauge shows the correct response then check your wiring loom for partial contact between gauge and sender (partial earth).

Hope this helps

Norm

[VinceGledhill]

Electrical guages have an ignition feed to one side. The other side goes to earth via the sender unit... wired like so (please forgive me if the diagram looks vague) -- =wires

--ign feed--Guage--Sender--Earth.

Now if you switch on the ignition and remove the wire from the negative side of the guage it should read 0. If it doesn't then the guage is faulty. If it does read 0 then wire an earth to this negative terminal. The guage should now read full. If it doesn't then the guage is faulty.

If the above test states that the guage is OK move on to testing the wiring and sender unit as follows.

Re-connect your origonal wire onto the negative side of your guage. Now with the ignition switched on remove the wire at the sender unit. The guage should read 0 at this point. If it doesn't and it checked out ok on test 1 then there is a problem with partial earthing on the wire. (replace this wire it's easier than tracing the problem)

If it does read 0 at this point then connect this wire to earth on the chassis or the engine. The guage should now read full. If not then there is a problem in the wiring (bad connection somewhere replace wire as above easiest) If the guage is reading full and all the other test work OK then it points to the sender unit.

Make sure that you have the right sender unit for your engine.

Hope this helps. Any further problems or need any clarification then please don't hessitate to give me a call on the mobile 07736 202101.

Regards
Vince
Time served Auto Electrician
Lucas Leeds 1979-1983