Oil Pressure Sender / Center Console Oil Pressure Gauge

So my oil pressure gauge is not working correctly. I pulled the blue/yellow wire off the sender and i believe the gauge is supposed to peg out when you remove this. My gauge doesnt move at all. When i ground it, i believe it is supposed to sit at zero. So it kind of sounds like my gauge is permanently grounded maybe?

Also when i turn the ignition to run, the gauge pegs out and then returns to zero. is it supposed to do this? Kind of like a gauge test to let you know the gauge is working. But it doesnt read the pressure. and doesn't peg out when the blue / yellow wire is removed to test it. 

Also when I start the car the gauge pegs out. So something isn't quite working properly. Any ideas or pointers in the right dir ction would be appreciated.

Is yours a 1.6 GTI that had a pressure gauge or you fitted one to a later 1.8 GTI?

no its a 1.8L engine. JH code. Car came with it……….not a mod by me. 

Shubbs said

no its a 1.8L engine. JH code. Car came with it……….not a mod by me. 

you need to trace the wires, the factory loom wires will run to the MFA/cluster for oil temp and warning LED/buzzer, not to run a pressure gauge.

There are loads of wiring diagrams on google to follow

If the wires are reversed I do think that when you turn it on the needle will peg.  So we know that your meter at least works.
But are the wires in the proper location on the sender?

I "think" they are correct Briano1234 but not 100% certain so will try that today. I kind of assume they are correct as the yellow one when removed stops the red oil light in the dash from blinking which I saw somewhere was a test to verify it's good. So I think they are but will double check that today for sure as that is way better than pulling my dash out again to hunt down some bad wiring!

Here is a pic autistically drawn that shows the wire colors on my 90 cabbies, and the position.



Blue/yellow is the Oil Pressure sender side, where the yellow is the on/off pressure switch that lights the dash.

Hey thanks for this Briano1234! I literally just figured this out. So I ohm-d out the blue/yellow wire from the sender to the gauge. After checking the Bentley manual it's supposed to go from sender to inside of dash as blue/yellow then jumpered to a yellow/red then backs out to blue/yellow and runs to the gauge.

I also found out that the sender is labelled 'G' and 'WK'. The 'G' is the blue /yellow in the engine bay and the 'WK' is the yellow wire. 'G' is the gauge wire, 'WK' is the warning light.

So long story short the blue/yellow in my engine bay didn't ohm out to my blue yellow at the gauge. So I pulled the knee bar back out and managed to see the tail end of the yellow/red jumper connected to the blue/yellow for the gauge so I pulled that connector apart so I could ohm out from the blue/yellow connector there to the gauge. So that ohm-d out fine so then checked the yellow/red jumper from the same connector to the engine bay. That did not ohm out. So I then pulled the fuse box down and started hunting around for the other end of the yellow/red jumper wire. Now during that search I accidentally found a blue/yellow connector not connected to anything so just thought I would ohm that out with the engine bay blue /yellow connector and low and behold that's the wire. Which wasn't connected to anything. So I then tracked down the yellow/red jumper connector and found that I had that connected to my fuel pump / sender wires which happened to be RED/YELLOW not yellow/red so I disconnected that and connected it to the blue/yellow jumper and hey presto all working now.

Sorry for the long story but felt it was worth the explanation. Silly mistake really but hey ho such is life.

I'm on to the next issue now which is a darn freeze plug leaking!! Aaaarrrgh!! Brand new plug and total pain to access!!