1998 ML320 shifting malfunction,no upshift - PeachParts Mercedes-Benz Forum

riske · #1 03-18-2007, 07:05 PM

This problem is intermittent. Here are the important details:
1. The vehicle shifts from 1st to 2nd but will not up-shift to 3rd gear and beyond.
2. This malfunction occurs intermittently during the course of any given day.
3. Engine temperature seems to have no affect on the problem as it occurs sometimes when the vehicle is stone cold as well as when the vehicle is at optimum operating temp.
4. The problem occurs more often during heavy acceleration than light acceleration, however it has occurred several times under light acceleration.
5. I serviced the transmission, replaced the filter, drained the torque converter, pan, and lines, and re-filled the correct volume of fluid with the correct MB trans fluid. I then re-checked the fluid level with the proper measuring tool. This had little affect as the problem still persists.
6. To-day I drove the vehicle about 60 miles. This problem occurred twice, both times after the vehicle was warm.
7. I have no sophisticated diagnostic equipment, only a $95.00 Innova code scanner capable of retrieving generic and some manufacturer specific codes. About a week ago the check engine light came on .I checked for codes and the only one set was PO700, Transmission Control System Malfunction. I erased the code to turn off the light, and the check engine light has not come on since then, even though the problem has occurred several times. However, when I scanned the car again to-day code PO700 was present.
That's about it...anyone know whats going on with this?

C32AMG · #2 03-18-2007, 09:15 PM

Quote:

Originally Posted by riske

This problem is intermittent. Here are the important details:
1. The vehicle shifts from 1st to 2nd but will not up-shift to 3rd gear and beyond.
2. This malfunction occurs intermittently during the course of any given day.
3. Engine temperature seems to have no affect on the problem as it occurs sometimes when the vehicle is stone cold as well as when the vehicle is at optimum operating temp.
4. The problem occurs more often during heavy acceleration than light acceleration, however it has occurred several times under light acceleration.
5. I serviced the transmission, replaced the filter, drained the torque converter, pan, and lines, and re-filled the correct volume of fluid with the correct MB trans fluid. I then re-checked the fluid level with the proper measuring tool. This had little affect as the problem still persists.
6. To-day I drove the vehicle about 60 miles. This problem occurred twice, both times after the vehicle was warm.
7. I have no sophisticated diagnostic equipment, only a $95.00 Innova code scanner capable of retrieving generic and some manufacturer specific codes. About a week ago the check engine light came on .I checked for codes and the only one set was PO700, Transmission Control System Malfunction. I erased the code to turn off the light, and the check engine light has not come on since then, even though the problem has occurred several times. However, when I scanned the car again to-day code PO700 was present.
That's about it...anyone know whats going on with this?

First step in diagnosing any electronic control transmission is to retrieve all fault codes, in all modules; another diagnostic tool is a copy of Transmission adaptation values. You will need a better scanner to properly diagnose the cause.

czopper · #3 05-23-2007, 12:33 PM

I have the same exact issue with a 99 ML320. I just had the transmission rebuilt ($3500) including torque converter, by Aamco, and the problem still happens! Now they are telling me that MB says it's either the MAF (mass air flow sensor) or the shift controller. I'm picking up an MAF today (local auto parts shop for $185 with core return) and will install it tonight. Will drive for a few days and let you know the results. If that doesn't work I'll have Aamco install a new shifter control ($475 for the part plus 3 hours labor).

Did you ever resolve your issue?

riske · #4 05-23-2007, 09:50 PM

Don't throw your money away on parts you are not sure you need. Take the vehicle to someone that is capable of proper diagnosis. You need to retrieve all the codes and go from there.I doubt that a place like Aamco has the equipment or knowledge to diagnose your actual problem.More than likely you paid $3500 for a tranny that you didn't need.

supradupe · #5 05-23-2007, 10:51 PM

Quote:

Originally Posted by czopper

I have the same exact issue with a 99 ML320. I just had the transmission rebuilt ($3500) including torque converter, by Aamco, and the problem still happens! Now they are telling me that MB says it's either the MAF (mass air flow sensor) or the shift controller. I'm picking up an MAF today (local auto parts shop for $185 with core return) and will install it tonight. Will drive for a few days and let you know the results. If that doesn't work I'll have Aamco install a new shifter control ($475 for the part plus 3 hours labor).

Did you ever resolve your issue?

chances are your $3500 was down the toilet for the unnecessary tranny rebuilt. sometimes it pays to have the dealer look at it before throwing your money away.

czopper · #6 05-24-2007, 10:45 AM

I did have MB diagnose the check engine code and all they got was PO700, Transmission Control System Malfunction. It's a very generic code so they told me it was most likely either the trans, MAF, shifter or Transmission Control Module.

Since I have a third party extended warranty they wouldn't pay MB to tear down the tranny so I decided to take it to Aamco. Once it was torn down the warranty company sent over an inspector who confirmed that it needed a rebuild. The warranty covered around 60% of the rebuild but it still has the intermittent issue of shifting from 3rd to 4th. Last night I installed a new MAF and it's probably to early to know if it resolved my issue but so far so good. Will post in a few days.

Thanks for all of your replies.

RISKE-Did you ever resolve your issue? What was it?

riske · #7 05-24-2007, 03:53 PM

YES....I resolved the problem. I took the vehicle to my MB Dealer and had the system properly scanned. Here are the results:

ETC-Electronic transmission control
CODE 41 Fault in CAN communication with control module N78(Transfer case module) or the transfer case position is implausible

CODE 137 A spuradic fault in CAN communication with control module N78(Transfer case module) or the transfer case position is implausible

ME2-SFI Motor electronics 2
CODE PO700-106

VG-Transfer case
P1831 Positioner motor or position sensor or power supply is faulty

When you have your vehicle properly scanned by someone competent who also has the right diagnostic equipment, you will obtain the transmission codes which are causing your problem. Code PO700 is a generic code ,NOT manufacturer specific to your vehicle.....

Take your vehicle to an authorized MB dealer and have it scanned. Insist on seeing and receiving a copy of the print-out of the scan. Only then will you know what is going on with the transmission.

After I had my ML scanned I bought a control unit from Caliber Motors, my cost as a repair shop was 211.56. It took me about 30 mins. to install. Its real easy to get at,it is located under the center console directly behind the shifter.

After the module was replaced the vehicle shifted perfect.

I also had a bad transfer case control motor which I replaced later replaced (also an easy job and inexpensive part)
I was told by some very knowledgeable techs that this could also cause a no up-shift problem. However in my case the problem was caused by the control module.

GOOD LUCK, and let me know how you make out
BILL

czopper · #8 05-25-2007, 02:53 PM

Bill-Thanks for the quick and informative reply. I'll take you advice and go back to the dealer and insist to see the codes. I'll keep you posted! Have a great holiday weekend.

supradupe · #9 05-23-2007, 10:48 PM

does the yellow triangle with ! flashes or stay on permenantly when this happened? It happened to my 98 few years ago and dealer replaced the transfer case position motor (163-540-06-88), problem solved.

lowpro · #10 06-11-2012, 03:34 PM

My Mercedes is not upshifting it won't go more than 30mph and when you release the gas pedal and press it slowly it wheel run better but still no more than 30mph even if It's hot or cold everyday

lowpro · #11 06-11-2012, 03:36 PM

Is anybody out there to help me