So here's the story.. I took my wife's 99' ML320 out for a little off roading -- She was a willing participant as were my two kids so I don't feel too guilty. Anyway, we're out climbing hills, going through the mud... having a great time until the car totally quits. The battery died. After some quick investigation -- dodging the intense stares from my wife -- I figured out that the alternator was completely filled with mud. A few bottles of Evian and a quick charge from my buddies Land Cruiser and we were off again. Everything was fine until later that afternoon when I took the ML out of Low Range and started down the highway to head back to home. About a mile out of the off road park the ML came out of gear -- no warning, no lights, no noise, it just dropped out of gear. I proceeded to pullover and stop, put it in neutral and then back into drive which worked great... we drove it home 400 miles without a problem. The cars been running great until last week (3 months later) when it came out of gear again -- same fix... pull over, neutral, drive, zoom...) Well it happened again last night while my wife is down visiting her grandparents (500 miles away from home)...:-{ My wife is really starting to get worried, which worries me because she's hinting she wants a new car and I really don't want a car payment.

Anyway, enough of my drama... Any ideas what could be causing the car to disengage from drive? Other than this problem, the car runs great: it get great gas mileage, doesn't make any weird noises, and it's a real pleasure to drive. After reading the "ML320 Stuck in Death Valley" I beginning to believe it's an electrical issue with the transfer case. My dad seems to think I have a transmission problem.

Here is my plan of attack:
1) Pray that my wife makes it home
2) Check out the transfer case wiring connectors
3) Change the transmission fluid (did not know this was possible until I read this Form -- thanks)

Beyond that does anyone have any other ideas and/or experience with type of problem with an ML? Any helpful advice would be greatly appreciated!

Thanks in advance...

I would look at the electric actuator for the range selection in the transfer case.

I've never worked on one, so I don't even know what it looks like, but I've heard that this could be a problem. I would guess it is not moving a level far enough. Maybe caked with mud?

__________________
Thank You!
Fred
2009 ML350
2004 SL600
2004 SL500
1996 SL600
2002 SLK32
2005 CLK320 cabrio
2003 ML350
1997 C280 Sport

Yep, I bet you it is mud... just for fun here's the mud hole that killed my ML320.

I had the same symptoms in my 99 ml430. Acted the same way for a while until one day it didn't want to go any where. I cost almost $4000 to get the transmission rebuilt. There were so many pieces of metal missing from the "teeth" on a lot of the components the transmission shop laughed. Turns out it's a common problem and there is a redesign on some of the components.
Good luck.

My wife's a/c quit working and the vents would not stop blowing heat. Also we were finding oil on the floor in the garage which was coming out of the a/c compressor. we took the car into the local "Indy" for repairs.
He replaced compressor, replaced reciever drier, replaced heater control switch. Heat was still blowing out of vents. He tested Temp Controller motor & it was fine. He checked for fault codes again & a/c system would not talk to his code reader. Freon is new. I'm 1700.00 dollars into this & its still not working right. He currently has a/c working (with vents forced open I think) to give us a/c. He says we will not have heat if we need it. Anyone have any thoughts as to another cause. I took the car back after (4) days at the shop. Guy says needs a few more hours to trouble shoot I thought that was excessive considering the time already spent on it. He's also stumped. Any thoughts would be appreciated. Thanks.

The saga continues but there may be a happy ending...

On the way to my dad's shop yesterday I hit a big bump doing about 45 mph and once again our ML popped out of gear. I figured that's three times in three weeks, I better start forking over the $$. Well I made it to my Dad's and loaded the car on his rack. As planned, I checked the transfer case wiring first. Everything looked good: there was no mud, no dirty connectors... nothing. It all looked great. Next I drained the transmission and torque converter and proceeded to remove the transmission pan. When I checked the bottom of the pan I saw a light coating of material which is what I expected/hoped to see from a transmission that has not had its fluid changed in 115k miles -- I didn't see any metal shavings and fluid smelled okay although is was a little brownish. I also check the tranny level before I drained everything an it was correct. Heck I was a mechanic for three years back in my college days so, I've seen some pretty bad transmissions and this one didn't look bad! Next I removed the shield that covers the wiring connector that inserts into the front right of the transmission and then removed the connector. I found the outside of the connector -- the part external to the o-ring -- packed with dirt which was no doubt due to my little off road adventure described above. I don't think the dirt was my problem but it did lead me very quickly to what I think was the problem. The twelve or so wires in the transmission wiring harness that run down to the connector are wrapped in a heat resistant cloth. When I examined this covering I noticed that that the transmission wiring harness was resting against a heat shield that protects the car from the catalytic converter about 9 inches from the connector. When I examined it more closely I found that the heat shield edge had cut through the wiring harness heat resistant cloth and had warn away the insulation on one of the wires in the bundle, the black one. I repaired the wire with some insulating tape and used a zip tie to connect it to the fill tube thus ensuring that the wiring harness no longer makes contact with the heat shield. Once that was done, I changed the filter and gasket, installed the "new" magnet and vowed to change the fluid every 30k miles. The car has been running great.

So, here's my concern/gripe.. how may other ML users have wiring harnesses that are being damaged due to the poor wire route? I've got to believe that just about everyone's ML has this problem, as chassis wind will definitely push the wiring harness into the heat shield and over time it will wear. I fixed this problem with a 25 cent zip tie but, I wonder how many other ML owners have had their transmissions rebuilt unnecessarily...

Anyway, for all you ML owners out there you may want to check to see if you have this potential issue.