oil pressure gauge goess off the scale?! help!

[Sleeper_Avant]

oil pressure gauge on my B4 goes right off the scale as soon as the ignition is on, any temperature and running or not.

pulled both wires off the sender with no difference?

anyone got any ideas?

also fitted new gauges today with no change, they have been "retrofitted" by the looks of it, any wiring diagrams etc?

not helped by "search function" or S2Central

cheers

Sean.

[UrS4boy]

If I remember correctly, when the oil pressure gauge goes off scale, it means that there is no signal to it, i.e. kind of a warning. Hence no difference when you unplugged it. Broken wire or broken sender.

[Sleeper_Avant]

after a bit of google action,

the big 2 pin sender and the single pin sensor BOTH feed the gauge? this correct?

also if i join the 2 contacts up from the big one it should read 0 bar?

[AndyP]

I'm sure only the big 2 pin sensor feeds the gauge, the single pin sensor is just for the autocheck low oil pressure warning.

[Monkeymagic]

possible one of the wires is shorting to ground giving full deflection

[Error404]

you have no connection to the WK post on the oil pressure sender

[UrS4boy]

after a bit of google action, the big 2 pin sender and the single pin sensor BOTH feed the gauge? this correct? also if i join the 2 contacts up from the big one it should read 0 bar?

The oil pressure gauge sender, F22, has two wires attached to it. Both are powered and ground through the F22. The F22 has both a gauge sender and a pressure switch inside. The pressure switch is 0.3 Bar and, on an AAN harness, the wire is Blue with a black stripe. The other wire is Black with white stripe and goes to the pressure gauge. If I remember correctly the harness either has different sized spade connectors or different sized ring terminals so you can't F it up too bad (only 50% bad).

The other pressure switch (the one that will die and p*ss oil everywhere), the F1 switch, is on a White/Grey wire on the AAN.

All three go to ground when they are active.

[Sleeper_Avant]

Dave, its on a non 5-cylnder, its a 4 cylnder 6a Sorry!

So again, joining the 2 wires with send the gauge to 0bar ?

[UrS4boy]

Dave, its on a non 5-cylnder, its a 4 cylnder 6a Sorry! So again, joining the 2 wires with send the gauge to 0bar ?

I missed the B4 part. My bad. Personally, I think joining the two wires together = bad idea. If they are like the AAN sender/switch, they both go to ground through the sender. Connecting them together = nothing to ground = electrical short??

[Rusty]

Have you got it warm or is that all when cold?

[Sleeper_Avant]

i see, i got lots of the car apart now anyway as its been nailed together very badly, might even pull the dash out to check for nasties!

will go and remove the harness and senders from the car i took the gauges from today, best idea i think.

is this a sub harness or part of the main loom that needs cut out on a B4?

[Sleeper_Avant]

Rusty, its all the time mate, had the car hot with the rad fans on and still off the scale so its not true pressure, its on the stop for max all the time! lol

[newsh]

IIRC on the UR this happens if the sensor wires are reversed, is it possible the wires are crossed over somewhere?

[Sleeper_Avant]

yes as they were just shonkey spade connector jobbies!

im just going to take the wiring from the donor car if its a sub loom, is it a sub loom or part of main harness mateys?

[Error404]

Try swapping the terminals at the sender. If that doesn't fix it, try grounding the wire going to the WK terminal on the sender (normally this has a plastic housing on it).
If the reading drops to 0 then the gauge is working fine, probably a connection or sender fault. If not, you have continuity issues between the sender and gauge. HTH