CLC 2008 (CL203) Wiring Harness possibly damage causing U0101 & Limp Mode

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New Member
Feb 13, 2017
Mercedes Benz CLC 2008
Help and advice would be very much appreciated.

Having some automatic transmission issue causing the car to go Limp mode. Car would drive but 30min into drive and the gear indicator and driving mode (P,N,R, D & C,S,M) in dash would disappear and reappear intermittently but would end up disappearing after causing the car to go Limp Mode. Scanned car with generic obd2 and it came with U0101, P0705 & P0720 (lost communication with TCM, Transmission Range Sensor Circuit Malfunction & Output speed sensor circuit malfunction).

The failed fix I have done so far to tackle this issue includes (in order);
1) topped up ATF oil to correct level (i.e. between the low and high marker at 80*C)
2) inspected TCM for oil whicking through the wires (no sign of liquid damage)
3) inspected 13pin connector for oil leaks on the auto gearbox and found a bit oil because I spilled some whilst topping up and the fluid run down the feeder pipe all the way down to the gearbox casing (although I should inspect this again just to make sure).
3) changed battery with new one
4) replaced gear selector module with a used one

Just to note, whilst inspecting TCM which was located underneath the passenger side foot area (bulkhead), I noticed that the area was damp and the NVH pad and the wiring harness going to TCM was wet (see attached photo). I inspected the leafscreen and found that the drain hose was not on properly to the leafscreen and it was also blocked. Unblocked now and fitted correctly into place.

I am not sure if the wiring harness is damage since it got wet but I thought I should check this since one of the code I got from Mercedes Dealers was an issue with CANBUS message from control fault (MB Star code: 2211001) after an hour session on the MBstar. So I would like to ask if anyone knows where I can get a electical schematic for my CLC 2008 CL203 so that I can check wiring continuity with a multi meter?

I am learning as I go along trying to fix this car and its been 2 months now since I have tried to fix it myself, hopefully there is light in the end of the tunnel.

Any suggestion is welcome!


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I inspected the 13 pin socket again today but this time I removed it to see if there was any leakage and it was dry and clean.

Kept looking around and I believe I found the ground wire to the transmission (can someone confirm) which looked rusty and brittle as if it was rusted (see attached photo). I began testing the wire for continuity by touching both side of the bolts with a multimeter but I hear no beep noise which normally indicates that there is no continuity. I only manage to get some beep noises when I touch the actually ground wire on certain areas. I also did a resistance check on the wire and it was giving me UL or unlimited resistance. So I am assuming now that I have a bad ground to my transmission.

Going to order a new ground wire and see if this fixes the issue.


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better perspective


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