99 ML320 Shifting Problem. Please Help - PeachParts Mercedes-Benz Forum

xbrxx · #1 10-02-2004, 03:29 AM

After going through the many threads regarding transmission issues, I have yet to pinpoint exactly what my problem is. I have a 99 ML320, that is out of warranty. A very good friend of mine is a ASE master technician and he is helping me repair the vehicle. He has the scantools to extract tranny codes, so I have those codes available to anyone who could help me out.

Anyhow, a couple months ago, every couple of days the car would either not shift up into a higher gear, stuck in 2nd gear it seems, or get stuckin 3-4th gear, and will not downshift when vehicle has slowed down to a stop. This means at a stop light it would accelerate extremely slow due to the higher gear. I would then turn the car off and turn it back on, and the problem would be gone. Back to normal.

A couple of days ago, the problem has came back, but this time, it is here for good. I tried turning off and back on to no avail. So right now, it wont upshift past 2nd gear. I initially presumed it was limp mode related, but my friend says a code related to the RPM sensor is being indicated in the computer. I dont remember the exact code number off hand, but I can get it again.

Anybody have any ideas? I'm guessing that the RPM sensor is faulty or something with the conductor plate and the RPM sensor. Is changing the RPM sensor something easy to do, and how much does it run cost wise?

Thanks,
xbrxx

sdanville · #2 10-02-2004, 12:18 PM

Hows that ?
My 99 has a dip stick in it.
A mechanic showed it to me after I said my manual said no checking or replacing of fluid for the life of the vehical was required.

sdanville · #3 10-02-2004, 12:38 PM

The mechanic pointed to the dip stick,
Thats what happens when one assumes.
I never pulled it out.
I'll check it out.. If there is a stick on my top I will send a photo.
at this point I doubt it.

supradupe · #4 10-03-2004, 01:38 AM

Does the low range lamp also flash? if so, the transfer case position motor may be bad, my 98 ml had the same problem. Dealer replaced the motor and all is good. The part # for the motor is 163-540-06-88, cost was $232 2 years ago and 2 hours of labor.

Gilly · #5 10-03-2004, 08:22 AM

2HOURS?????? Man that's a 1/2 (.5!) hour job, tops.

Gilly

sdanville · #6 10-03-2004, 08:52 AM

Gilly, don't mechanic's just go by the book.
if they are fast - good for them.
if they are slow the customer doesnt get burned.

supradupe · #7 10-03-2004, 12:26 PM

that's what the invoice shows, I didn't have any info to compare with or argue with at that time. Meat is on the butcher block, not much I could do. Where exactly is the transfer case position motor anyways?

Gilly · #8 10-03-2004, 07:23 PM

It's the "transfer case low range motor", there are some motor position switches built into this electric motor that tell the low range control module the actual position of the motor. The switch assembly isn't available seperately, so a failure means you need a new low range motor.
It's bolted EXTERNALLY onto the back of the case, one electrical connector and 3 bolts and it's in your hand. I could have it removed in less than the time it took to write this (assuming it was up on the hoist ready to go).
It looks like a wiper motor, it's pretty easy to see it.

Gilly

xbrxx · #9 10-08-2004, 01:41 AM

Thanks for everyones reply. While I was away on business for a couple of days, my friend replace the conductor plate. Still same problem. I'm thinking perhaps I should just bring it to the dealer. Aftermarket service manuals do not provide enough information. Alldata, Mitchell, useless.

BTW, with the new conductor plate in, we are getting the code P0715, Input/turbine speed sensor circuit/ RPM sensor function. I have no idea what this means at this point, anybody got any ideas?

jfreezn · #10 10-08-2004, 03:14 AM

Quote:

Originally Posted by xbrxx

Thanks for everyones reply. While I was away on business for a couple of days, my friend replace the conductor plate. Still same problem. I'm thinking perhaps I should just bring it to the dealer. Aftermarket service manuals do not provide enough information. Alldata, Mitchell, useless.

BTW, with the new conductor plate in, we are getting the code P0715, Input/turbine speed sensor circuit/ RPM sensor function. I have no idea what this means at this point, anybody got any ideas?

Since your friend was in the trans, did he change the oil and filter?

A strong possibility is the shift lever is out of adjustment. There is a feedback electronic circuit that tells the computer what gear you have selected. If the linkage has slipped, you can confuse the computer and throw it into the limp home mode. Put the trans in park and look to make sure the shift lever on the side of the trans is touching the metal stop bracket. If all is in proper adjustment, you will not a very smooth movement of the shift knob through all the gears with no hangups.

If not, loosen the "torques" set screw on the shifter rod and move the shift arm over to the stop.

Jim in Phoenix

#11 10-08-2004, 09:23 PM

Quote:

Originally Posted by jfreezn

Since your friend was in the trans, did he change the oil and filter?

A strong possibility is the shift lever is out of adjustment. There is a feedback electronic circuit that tells the computer what gear you have selected. If the linkage has slipped, you can confuse the computer and throw it into the limp home mode. Put the trans in park and look to make sure the shift lever on the side of the trans is touching the metal stop bracket. If all is in proper adjustment, you will not a very smooth movement of the shift knob through all the gears with no hangups.

If not, loosen the "torques" set screw on the shifter rod and move the shift arm over to the stop.

Jim in Phoenix

before you make any adjustments, make sure the shifter bushings are still intact!

Gilly · #12 10-08-2004, 09:36 PM

He first shopuld try clearing the code, see if that fixes it or if it's still a current code. If it's still current it could be a bad electrical coupler (that's the part the harness attaches to the transmission with, but kinda doubtful on that. He can laso look in the actual value screen and compere front and rear rpms.
Other possiblity would involve removing the valve body again; he can remove the valve body and look at the small square "window" in the bottom of the case and make sure he can see the slotted sheetmetal bracket that surrounds the front cluster, they were originally pressed into place and can slip so the sensor can't "see" the slotted bracket any more and won't pick up the speed. The newer versions were spotwelded.
Gilly

Jim_P · #13 10-09-2004, 10:05 PM

Isn't this the speed sensor in question ?
http://www.carsoft.ru/avtorepair/722_6_5.html
I am having the same exact problem with my 97 SL600. I am nervous about diving into the transmission blind. I get ODBII code P0715 the car shifts hard into drive becuase the eletronics of the transmission are disabled when in limp mode. If somone has detailed info on removing the valve body and could share it with me I would really appreciate it.

I'm losing patience with this car very quickly. I just got done replaceing the master cylinder ($1400), all for shock accumulators ($800)and now this happens

I do all my own work and save quite a bit on the labor, but this is getting out of hand. I was reading a little further in the forums and I see that this is related to the condutor plate. I think that is my next logical move. So it's off to the dealer Monday to see about getting a new one.

xbrxx · #14 10-10-2004, 09:47 PM

Thanks for the tips you guys. When we initially removed the valvebody last week to change the conductor plate, he also changed the oil, filter and gasket. He also cleared the memory, hoping to get it out of limp mode, but after 2 restarts, the code reappears.

On friday, we removed the valve body again, this was before Gilly's tip, and checked to see if perhaps the conductor plate was somehow properly installed, incase of any human errors. Nope, everything looked good. We also looked to see if that shifter was out of place, everything was right. However, when we took out the valve body for the second time, I do not recall seeing any sloted sheet metal in the windows. Perhaps, I wasn't looking carefully though. I am going to ask my bud if he remembers. Is the sheetmetal you are referring to the impulse rings as shown in Jim P's picture?

xbrxx

Gilly · #15 10-10-2004, 11:18 PM

Yes, the part they call the impulse rings can come loose on the early models. The originally "staked" these into place around the drums, oops found out they might not be staked very well, started spot-welding them in place. So yeah if you look where the 2 speed sensors enter the case when installed (look like squared-off holes) you should see these sheetmetal "bands) with square holes, these are what the rpm sensors "see" when the transmission is running.

Gilly