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Mercedes-Benz
ML320
27

Transmission May Leak Fluid and Damage Control Module on Mercedes-Benz ML320

Problem Description and Possible Solution

The electrical connector at the automatic transmission may leak fluid. Over time leaking fluid could migrate through the wiring harness and damage the transmission control module. If that happens a new harness and control module may be necessary to correct the problem.

Problem Data
RepairPal Verified
Average mileage: 146,647 (60,000–220,000)
6 model years affected: 1998, 1999, 2000, 2001, more2002, 2003
27 people reported this problem
Comments
Viewing 1 - 11 of 11 comments
Check engine lit came on. Vehicle went into "limp" mode. OBD II read 0715. Replaced conductor plate, harness connector, pan gasket and filter. Noticed leak at connector during disassembly and cleaned with WD40 prior to reassembly. Worked to get out. Of limp mode unseccessfully, but it did not throw the code again for 3 days. When it did, I went back under and pulled the harness connector to find more fluid, this time running down and out of the wiring harness itself. Inspection at the TCM shows the fluid had not made it all the way up. Now saturating lower part of harness and connector with WD40. This is thinning the tranny fluid and allowing to run out of the harness and connector. I am hoping this will keep the fluid from advancing any further toward the TCM. wish me luck. Otherwise it is a new harness.
My ml320 stuck in second gear, I change the transmission oil, and filter now, I notice it has a leak and still stuck on second gear
oil leaks underneath the dash passenger side, wiring to the electronic transmission unit I think part no. a 303 545 27 32, is this cable or wiring connected down to the transmission or if coming from the transmission, please let me know thank,s email artransmed@roadrunner.com
Had trans problem where would not shift into higher gears. Brought to Aamco, Henderson, NV and fixed the problem, said there was oil on the wiring harness. Now I cannot pass the emissions test because check engine light stays on and test says I have a transmission control module problem.
The gear was frozen, it would not change, wire harness to transmission needed to be replaced, transmission fluid was full. Still working on problem ordering wiring harness.
One of the top items on my wife's dream list was to some day own a Mercedes. Her brother in California had a 2000 ML 320 that he could no longer afford to drive so he give it to my wife. In November 2016 the Mercedes shows up in my driveway in Colorado.
I pulled it in my garage and there it sat until February 2017 ( I started it up each month and let it run for a few minutes to keep the battery charged up). I checked the gauges to make sure it wasn't over heating and other possible problems. In February when weather warmed up a little I started to check overall car closer. The first thing I noticed was big oil stain on my garage floor in transmission area. On February 24, 2017 I drove the car to my trusted service garage, discussed the history on the car, then asked them to do the following to ensure that it was safe to drive vehicle---
*Drain radiator, flush system, install new antifreeze for protection down to -30 degrees.
* Oil and filter change * Tire rotation * Perform detailed World Class Inspection on car and report back any findings
* I advised them about oil leak and asked them to locate leak and repair.
* I advised them of loud tapping noise in dash board (glove box area).
They located oil leak and "resealed transmission pan and sensor wiring harness(4- 00198968031 ATF, 1-Plug Adaptor, 1-Gasket)
Tapping Noise- Found blend door actuator failed, Installed new Actuator (Parts & Labor, $1326.98)
Total Invoice $2282.72
I picked up car on February 27th I headed for car wash (3 miles away) to clean car up for further detailing and to wash under carriage of car. When I left the garage the car seemed to running okay, on the way I had to stop for red light. When I got green light I pressed on the gas pedal and the car would not pull away in lower gear, just verily moved forward at slow pace. With many cars behind me it was getting interesting, thank goodness I finally got up to 50MPH and moved with traffic. Luckily, I made it to car wash with no more red lights, made it into car wash and through the car wash. I then spent 45 minutes wiping down exterior of car and vacuuming interior of car. Now the fun begins again, I pulled out of the car wash and headed for home. I started down the road okay, but then the car would not shift out of 1st or 2nd gear. I had to pull off the side of the road many times to allow cars to pass, the highest speed I could drive was 35 - 40 MPH. I also shifted car back into park and then back into drive to see if transmission would shift right. I drove the car back to the service garage and told them about the problem. After keeping the car for 5 weeks they replaced "Valve Body" but that did not resolve issue. They then sent car to a transmission shop for assistance in resolving problem, they opened up transmission and inspected everything. They were unable to resolve as well. Parts installed--- 1-Valve Body 1-Plug Adapter 1-Gasket 4-ATF Total Invoice $1081.13.
I drove the car home with transmission still stuck in lower gear on April 7, 2017.
I have read that this happens quite often in the 2000 ML 320 and it sounds like if you know what you are doing it is easy to resolve issue---HELP.
Educate me more on "wiring harness" located by transmission and BCM/ECU 787839 Trans located under dash board.
P.S. I forgot to mention that "Check Engine Light" come on as I was driving from car wash back to garage, it is still on.
Someday I would like to take my wife for a ride in her "Mercedes."
Thanks, Colorado Ed