I have installed the engine loom and dash loom out of a AU II LTD into my EL and rewired the rear section to match. So basically everything forward of the dash is AU.

However the XR dash I have, the oil gauge doesnt work, have checked the sender, they are the same as the EL XR one, previous EL XR dash worked fine. Checked all the wiring between the sender and the cluster all good. The odd thing is, disconnect the sender and the gauge reads 3/4, earth it and it reads 0.

At first I thought I had a faulty dash so got a new 2nd hand one and it does the same thing. Tried in another car and still the same. From what I have I gleaned from the workshop manual, the wiring is the same for the LTD and the XR for this part of the dash.

Anyone got any ideas on the cause?

Hmm so your trying to use an el xr cluster, but the oil guage is playing up, is the temp sensor working? and is the rest of it working?
have you tried another oil pressure sender, I've heard they can be a bit temperamental.
I would've thought the LTD cluster would be a bit different as you've got door sensors etc. running through it, even isn't traction control run through there?

I've got an au3 fairmont cluster sitting here by the way if your interested.

No I'm trying to use a AUII XR cluster. Everything else is working as it should be. Even with a brand new sender same problem. Tried a different cluster with the same result. Next thing I want to try is plugging my cluster into another XR and see what happens

What I wanna know is how you managed to fit such a cluster into an EL dash??

easy once you have AU wiring. Slight modification on the EL facia, and the AU dash will sit in place, then the facia keeps it there.

have a look HERE (registration required unless already a member)

Man that AU XR cluster looks pretty good in the EL. Great work!! So its basically an EL with almost everything AU now

The problem with the oil pressure gauge seems very odd, especially when you disconnect the sender and it starts reading, it doing the exact opposite of what it should be doing when connected lol

Could the dash loom be at fault? Lol i wouldnt have a clue but just throwing it out there

The oil pressure "gauge" on the AU2/3 is a fake. Just like the temperature gauge in the same models.
It simply has two positions, its just a pretty warning light.
The AU1 had both gauges as working items.