722.6 transmission electrical problems... - Mercedes-Benz Forum

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post #1 of 4 (permalink) Old 09-23-2012, 11:41 PM Thread Starter
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722.6 transmission electrical problems...

I need help diagnosing a 'power supply error' problem to my ML320 transmission.

Currently Carsoft 7.4 is reading the EGS (transmission control Module) as having the faults ;
010: Solenoid valve: Power Supply Error
106: Solenoid valve: Power Supply Error
107: RPM Sensor: Power Supply Error

These faults cannot be cleared. Carsoft is also reading the main 'ME' module as P0702: transmission Control Unit Electrical
P0715: Input/Turbine Speed Sensor Circuit Malfunction

These two faults will clear using carsoft but will return as soon as the car is started up again. But the EGS faults remain

The conductor plate has been replaced just 2 months ago along with all the o'rings, seals and the connector plug etc. I have since removed the 13 pin connector to check for oil but it was all clear and dry as was the TCU. I did not remove the 'male' version of the plug inside the transmission (the one secured by the 7mm nut/screw).

I changed the conductor plate due to errors related to various sensor faults. The vehicle ran fine for appx 2 weeks and then it went in to limp mode again to where i now have the 'power supply errors' to the solenoids and the rpm sensor.

ANY IDEAS...what i could do/check.. I also purchased a second hand 'Transmission control module' but that made no difference.

Also, when I removed the 13 pin connector plug to check for oil recently, I cleaned with electrical contact cleaner and reassembled. The faults cleared at that stage and the vehicle was fine for about day until it went into limp mode again. (having said that i dont know what the exact 'error codes' were then as I had to have the local service tech clear them for me)

The vehicle has done 273K.

Any help appreciated...
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post #2 of 4 (permalink) Old 09-24-2012, 04:05 AM
Date registered: Jul 2005
Vehicle: 90 300E, 99 ML430, 00 ML320, 05 E500 4matic Wagon
Location: WI
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The codes have to be cleared from the TCM and the ECU. If they are not cleared from both locations they will return.

You may want to post this in the W163 forum we have here.
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post #3 of 4 (permalink) Old 09-24-2012, 01:03 PM Thread Starter
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The codes wont clear from the TCU...
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post #4 of 4 (permalink) Old 09-27-2012, 12:37 PM Thread Starter
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To update my transmission problems.... I decided to investigate further the actual wiring harness that connects to the transmission. What I found was most of the heatshield wrap that encases it had gone/perished - within 200mm from the connector (at the transmission). I easily peeled back the outer sheath to expose the wires and 'whatdoyaknow'.. most of the wires had their insulation melted or perished leaving the wires exposed and perhaps even fused/shorting together. A new wiring loom wasn't an option (AUD$13,000) so i spliced in new wires - 12 or 13 of them, (tricky under there) and fully encased with a new heat shield.

Result... Perfect - No sign of any of the consistent problems with the transmission and going into the dreaded 'limp mode'. 'Touch wood' it stays that way.

It seems with all the techo's diagnoses including the replacment of the conductor plate and accessories, including the TCM (transmission Control Module) was perhaps the complacent 'simple' fix.
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