Airbag

Thanks, this one is really interesting.

nzaudia6

Audi performed the tests today by isolating the instrument cluster and sending various signals to the gauges to check their function. The tech explained that they cycle through the gauges one by one sending the needles to full position then to half to check they are calibrated then back to zero. The Oil Temp gauge was functioning correctly under the VAGCOM. They also swapped the oil level sensor with one they knew worked just to be absolutely sure (and then swapped it back again later to my new one that I put in last weekend).

Knowing all of this it is now pointing me to the wiring between the oil level sensor and the dash. Dare I say it Airbag but your Post #15 to check the wiring seems to be spot on.

Does anyone have have a wiring diagram for this or a part number for that part of the loom because I'm having trouble locating it in ETKA. Looking at the plug to the Oil Level Sensor, the 3 wires disappear into a sheath - I'd like to know where they go to from there..

Airbag

i have a schematic but that is about it .. i can maybe see where it runs , are you talking about the sensor in the oil pan ? are we in agreement the oil level and temp comes from that sensor in the oil Pan ?

..okay her is what i got .. fuse 5 is a 10 amp fuse and it dedicated to supplying power to the oil level/ temp sensor ( pin one ) .. schematic says it will be a blk/red or red/white wire ( may depend on engine type .. )check for voltage at the connector first .. will be hot with ignition on.

Pin 2 is brown and will be ground .. check that for continuity to ground for sure..

pin 3 red/green or brown/ red and goes to pin 15 of T32A of the instrument panel connection.

Good luck ..

pretty fancy engineering if they can get temp and level off one wire .. i have a feeling it may have something to do with voltage level outputs and a fancy algorithm .. still pretty impressve tho .. when it works i guess

nzaudia6

Thank you Airbag. Huge help. Here is what I did today.

You are right that the oil level sensor has 3 wires and yes we are in agreement that the oil level sensor and oil temp sensor are the one and the same. The sensor has 3 wires; brown, black/red, and red/grey

Brown is earth.

I researched the net last and found a post that explained where the wires from the oil level sensor end up. If you open the box that contains the ECU which on my car is at the base of the windscreen on the RHS. Behind and under the ECU box are the main body harness plugs from the engine wiring loom.

There is a black plug, a red plug, white plug, and a brown plug. The brown plug is called T10A. It looks something very similar to this picture (not taken from my car but is a pic off a year 2000 Audi S4).

Then you have to find the Brown ten pin T10A plug (second from the bottom in the pic). Pin #8 on that plug is black/red one that goes to pin #1 on the sensor. Pin #9 on that plug is the red/grey one that goes to pin #3 on the sensor. The brown wire is earthed through the loom.

I check the resistance through the wires and all three are good up to that plug.

I'm now going to focus my attention on that Fuse #5 - that's gold that you confirmed that is a dedicated fuse for exactly the two things I'm having problems with. I'll replace that one tonight.

If that doesn't change things ill be looking at the connector plug at the back of the dash cluster.

Thanks again for your continued help

Airbag

Check voltage from pin 8 ( pin 1 on the sensor ) to ground with your multimeter. If you have 12v with the ignition on You are good.

nzaudia6

I changed Fuse 5 in the weekend hoping for an easy fix but it didn't make any difference.

I will try to check the voltage as you suggest over the coming week.

One thing I noticed after changing the fuse was that when the oil was hot after driving, if I turn the engine off and then on again the oil temp gauge rises to what I presume is about the correct indicated temp (around 90 degrees C) but then over a period of about 30 seconds it sinks back down to the low mark (60 degrees). I had never noticed this happening before so I can't be sure that it is related to the fuse change or is just coincidence?

It was almost like there is some internal resistance building in the signal increasing immediately after start-up over that 30 sec period.

Airbag

Just to confirm, you have a hella sensor in there right?

nzaudia6

Absolutely! And the Audi dealer checked the operation of mine to confirm it was ok.

Airbag

Well if the wiring checks out I don't know what else to suggest. Has to be a resistance building up at a connection somewhere.

nzaudia6

Latest update.

Checked the red/black wire at the sensor with ignition on - 12V. All good there.

Checked for 12V at the brown connector. All ok too.

Then followed it through to Pin 15 on the green T32 connector at the back of the cluster and that is ok too.

This leaves only the dash cluster as the culprit. To confirm this I borrowed a dash from my friends B5 RS4 and plugged it in after a drive and the oil temp immediately rose to around 80 degrees and stayed there (rather than the needle sinking like on my dash).

Unfortunately the cluster for my car is about NZ$1800 (USD$1400) from the dealer so I'm now going to be hunting around for a used one.

I'll be starting a new thread soon around cluster compatibility starting with this thread as a base;

https://www.audiworld.com/forums/sho....php?t=2798354

Thanks for all your help along the way.