analystguy

I am at my wits end chasing down the cause of the intermittent limp home mode.I am hoping other owners have had similar experience as to what I should try next. Please help.

Symptom - 2002 ML320 was intermittently (every other day and usually first thing in the morning) hard shifting into drive yet the indicator will show position other than drive. At this point a P0705 code was generated causing CEL to illuminate. ATF was evident on the transmission pan. As well, the Transmission control module was slightly damp - evidence of wicking ATF from the pan to the TCM.
Low Range Transfer Case motor does not work and Low Range Light flashes numerous times before it extinguishes.
Truck appears sluggish to drive.
Truck has 200,000 km


What I did.
1. replaced the transmission fluid and filter as well as the connector plug (brand new O rings).
2. Opened the Transmission Control Module to discover almost no AFT had leaked inside the unit (only 1 drop that I could see). Cleaned unit and connectors the best I could using contact cleaner and compressed air and reinstalled unit.
The result:
Still getting intermittent P0705 errors.

Some History:
A couple of years ago I pulled the shift module from the truck to try in another ML to make sure part was defective. It seems to me I dropped and lost one of the 3 anchor bolts that secure the shifter into place

Car seemed to drive ok. I can up shift and down shift to all 5 speeds.But the car does feel sluggish when compared to my other 2001 ml320.
I noticed that after cleaning the TCM and reinstalling it, the truck tends to go into limp mode more often.

Question: What should I try next? Given the intermittent nature of the problem, could the issue be a misaligned shifter?

Thanks
Dave

khomer2

No mention of scanning and erasing the codes after your repairs.

Maj. Dundee

Codes must be read and deleted in both the ECM and Trans. Cont. Module before you can getting back to working order.

analystguy

I neglected to mention that after each error I would use my scan tool to delete the error and rescan to ensure no DTCs present.

One thing else I neglected to mention is that before draining the transmission fluid I was able to view real time transmission data on my scanner. Now N/A displays on all transmission values. Could I have improperly placed the transmission harness into the transmission adapter plug?

analystguy

khomer2 - If it makes you feel any better spent about 3 hours reading through the different post and searching for the P codes I was receiving prior to posting.

khomer2

Why the dig?

Check your connection with the adapter again to ensure all the pins are aligned and not bent when you re-installed the GENUINE adapter plug.
Other area of issue of the generic P0705, can be your conductor plate ====> possible warping = speed sensor issues.

Lastly, sluggishness could be an entirely different issue.
Go search and research some more - 3 hours of reading is nothing in the scheme of things - you seem to have a handle on things

analystguy

khomer2 - no dig intended. I appreciate your reply - thanks.

Because of the amount of ATF showing on pan, I replaced the transmission adapter plug and locked the harness without issue. There is no additional leaking that I can see three days after the repair so I believe the source of the leak is repaired. As mentioned the other end of the harness showed some ATF on both connectors that plug into the TCU. I cleaned these out with contact cleaner and compressed air as best as I could. I also disassembled the TCU and noticed only a single drop of ATF on the board. I cleaned this off with a shop towel and reassembled and reinstalled it.

After repairs, I used my MB specific scan tool to remove all DTCs from the car. The very first attempt at putting the car in Drive results in a hard shift (car in drive but indicator showing neutral). The problem was still there only it seemed worse and more frequent than before I cleaned the TCM.

I again removed the TCM and this time cleaned it with MAP cleaner as others on the forum suggest. I also sprayed MAP cleaner on the connector plugs. I let everything dry before reconnecting. Using my scanner I again removed ALL DTCs from the vehicle before starting. It has now been an entire day and I've not experienced any further shift issues.

I know this might be premature, but the lesson I have learned from this is to use MAP CLEANER to clean the TCM and connectors. I will report if anything changes in the near future, but for now, everything looks good.

analystguy

I guess the lull was too good to be true. Hard shift has returned.

Following are the DTCs present -
Transmission
P240c the selector lever position sent from control unit N15/5 (electronic selector lever module control unit) via the CAN bus is implausible

Esm - electronic selector module
P1856 shift lever position identification failure
P185602 not found in db

Me2- sfi motor
P0267-004 not found in dB
P0267-016 not found in db
I am now in the process of replacing the shifter. Stay tuned.

Maj. Dundee

Try and replace the shifter correctly this time and get a new bolt that you lost.

analystguy

I replaced the shifter with one I ordered on ebay that appears to be in brand new condition. While it is true that it "fits" a 2002 ML 320, the part number is different than the shift module already in the vehicle.

Origin part number - A 163 545 84 32
New part number - A 163 545 92 32

After replacing the shift module, I re-connected the battery, reconnected my MB scan tool, turned the ignition on to position 2 (ON- not started) and proceeded to clear any DTCs.
With respect to Transmission Module itself, I could not clear code P2313 (a new code associated with the new shifter). In addition the vehicle would shift hard into any gear I tried.

After meeting with failure, I again disconnected the battery, removed the new shifter and replaced it with the old one. After reconnecting the battery, I was able to scan and clear all codes in all modules including the P2313 code associated with the new shifter. With no DTCs present, I am now able to smoothly shift into any gear with the old shifter. But at some point the P0705 P240C codes will come back as this still is a transient problem.

My take away is that you must make sure to replace with the correct part number. I know it sounds trite, but it is not sufficient to rely on the fact it "fits" your year make and model.

Maj. Dundee - thanks for the schematic. As it turned all the bolts were there.
khomer2 - I am hoping its not a conductor plate although it remains a possibility. (Especially after just having replaced the ATF and connector plug with parts ordered from MB).
My next step is to pull the shifter out of my daughter's 2001 ML320 and give it a try. It is brand new. If the faults don't return, they I will buy the correct shifter. If they do return, then its time to look at the conductor plate as I'm satisfied the TCM itself is in good condition.

Another reason why I am leaning toward the shifter being faulty is that I notice when downshiftng from drive to fourth, or from fourth to third - as soon as I release the shifter the transmission reverts immediately into drive. I must keep pressure on the stick in the negative direction to maintain a lower gear down a hill..

If anyone needs a shifter that appears in near new condition, let me know. Part number is A 163 545 92 32 I believe it belongs to an ML55.

Dave

Maj. Dundee

What is you full vin#

analystguy

Maj. Dundee - Full VIN is
4JGAB54EX2A347538

Maj. Dundee

According to your vin #, you have a 2002 ML320. Your veh was produced Apr. 8 2002.

And according to your vin#, this is the correct part #.

Please update your profile to make it a 2002.

analystguy

Wow - thanks for the research!

Not to introduced confusion but I actually have two ML320s- one of which I gave to my daughter and I maintain it for her. I have the 2001 - she has the 2002. Go figure.

According to your schematic, the correct MB part number of the shifter is 163 260 10 09. That is the part number of the shifter I purchased from ebay and the one that is giving the P2313 code that I cannot delete.(see picture below).

Given it is the correct part number, was I sold a defective shifter?

Maj. Dundee

Well then there must be a problem with the replacement shifter.

analystguy

I bought this shifter from Gold star auto parts on ebay and they refused a refund or exchange. Buyer beware. I'm out $700 with shipping.

I note that the R&I Shifter 2000 #2.pdf above shows an adjusting shift rod that comprises a rod head and bolt (items 98 and 99) where the shift rod joins onto the intermediate shift lever. The below picture shows that this seems to be missing on my shift rod end. Could that play into this? I also note what appears to be ATF at the base of the shifter pad.

Maj. Dundee

This is what happens when you try to replace the shifter from above and that's why I posted to get a new bushing in post #9.

analystguy

I think the shifting issue has been resolved as I've not experienced limp mode or a hard shift during the past seven days. I attribute the success to replacing the connector plug and cleaning the wiring harness connectors at the shifter and transmission control module as well as the transmission control module itself. It seemed to me that if the issue was a shifter or transmission control module (electronic components) the problem would be there all the time. The intermittent nature of the problem led me to thoroughly clean the wiring harness and connectors as best I could using MAF cleaner.

Hope this helps someone else.