I have now resolved my none working oil temperature gauge in the instrument cluster. It was showing a constant -40F (which means no continuity to the ECU in one of the circuits)
I ended up making my own schematic for the ECU pin out so I could trace all the wires related to this (see the link below for the schematic)

https://mbworld.org/forums/coupe-roa...u-pin-out.html

Today I got the time to do the tracing and I found that I did not have continuity from the oil temperature sensor to pin# 36 of the ECU. I now have installed a new wire along the original harness and spliced it in at the sensor and ECU. All is well now zero SDS codes and the ECU distributing the proper signals to all the related modules that need to have the temperature input in order to work properly.

So now it was the right time to mount my new plates of the car.

After splicing all is resealed and connected

It used to read -40F for the oil temperature (-40F is the default is there is no connection)

 

Very cool...and appropriate plate Hendrik...Time for a Guldon Draak!

 

Great job with the fix though unusual to have lost connectivity to start with - has the car ever been hit/fixed or disassembled prior or was this always an issue since you got the car?

 

I knew that the car was never hit or wrecked but that it needed a motor to be replaced when I got it back in January, Before hand I had already located a replacement motor from a car with 13k miles on it that had been hit and was going to be parted out.

I normally do all my own work on my MB's and sometimes for others. I have a great working relationship with my nearby local MB dealer and as I was busy in the middle of a rebuild on a MB V12 at that time we talked and they where interested to do the engine swap for me based on a slack time fill in work (+/- 3 month). I did visit the dealers shop at least once every week to document, take pictures and discussed with the Tech the work in progress. It was during one of these session that since all of the drive line parts where out we decided to upgrade the carbon fiber drive shaft to the latest beefed up version.

Anyway at the end of 3 months I was getting anxious to pick up the car knowing that I would have to complete the AC work and deal with the none working oil temperature gauge issue (which initially was thought to be just a bad sensor).

So the issue of getting the oil temperature gauge to work got spread out over several weeks as I still have a few other cars to take car of as well.
Normally there wouldn't be a connectivity issue perhaps the engine swap caused it, who knows the final results are now there are zero SDS codes and the car runs great.

It looks like these hard to tackle jobs end up in my place often and in the end the research time to cure usually is longer than the time it takes to fix it ones you know what went wrong.

Go figure now when I get some spare time I get dig into the original motor that came out of the car to find out what went wrong! (I think the PO ran it out of oil, we shall see one day)

Thanks to all that replied, enjoy your cars, happy motoring.

Best H

She is ready

More MB work on hand

 

Gotcha, you were the one that picked up the car with the bad engine a few months ago and swapped in another - makes sense now. Btw, nice TX plates - I’m in north dfw!