This is the weirdest s*&t ever! My wifes ML320 beeps and lights up the first four warning lights from the left and the "brake" light on the right. Then when this happens the tranny gets stuck in whatever gear it's in at the time this happens. If you try to manually shift it (tiptronic thing + -) nothing happnes. If you put it in reverse it's like it's in neutral, and when you shift it back to drive, it's like in neutral...you accelerate and it revs, but nothing happens. Now, if you turn in off and then back on...it's OK till the next time. WTF? Help!

 

The only way to find out whats going on is to have the faults read out by an MB dealer with the STAR diagnostic system, not Autozone or any other but the dealer. That should pretty much pin point the problem but it sounds to me like the electronics module from the trans is the problem. Anyone spill liquid on the consol?? This one could be expensive.

 

SYMPTOM
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This is a common sign (early stages) of a transmission going bad!.

The best , and only effective diagnosis is to get the SDS connected at the dealer to read where the problem is (1. Transmission itself, 2. Gear Selector)

If the transmission is ok , then immediatly change the fluid. That improves things dramatically.....

PROBABLE CAUSE
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If you are lucky one of the rpm sensors in the ECU are gone bad ... that means you need to drop the pan, remove the ECU, replace the sensors. If you have an older ML320 then get the tech to put a magnet in the pan.
(see my diagram for the sensors). My tip is one of these RPM sensors are gone bad .... No point doing a repair if you have shinny particles in your fluid .... better off just getting an exchange transmission ... I have written a DIY for this!.

FYI: The electronics (ECU) of the transmision is buried in inside (bottom) of the transmission. There is an electrical connector from the outside. Sometimes the ECU supplies the correct information to the top gear selector inside the car, but the switches on the selector are damaged. This is however quickly diagnosed by the SDS.

The check you can do is to use the "fluid level " link below to make sure you don't have any particles in the fluid. Level checking unfortunately requires a separate dip stick, and reading via temperature of fluid.

If you have the "stuck in gear" "neutral" behaviour , then don't drive to vehicle. Have it checked immediately.

MB Transmissions (722.66x) usually last between 100k KM and 200k KM. After that they are definately going to fail!. If you have less than 100K KM , then Mercedes should take some of the costs of replacment.


LINKS
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Video
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http://www.auto-video.com/product_detail.php?id=10


Fluid Change
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http://www.mercedesshop.com/Wikka/Trans7226Fluid


Dip stick
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http://www.etoolcart.com/browseprodu...e-ASM7226.html


Quick Reference
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http://www.bulkpart.com/Merchant2/me...ercedes-lookup


Overhaul Kits
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http://www.drivetrain.com/mercedes_dt.htm



A reset of the Adaptive learning might help also:-
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This procedure resets the transmission ECU adaptive learning algorithm:
1. Turn the ignition key to the on (not start) position.
2. Press the gas pedal to the floor and hold for five seconds.
3. Turn the key to the "off" position (don't remove the key), then release the gas pedal.
4. Wait at least two minutes for ECU to reset.

 

So to sum things up ....

1. Get the SDS diagnosis ASAP to determine if it's just a sensor in the ECU, or at best a part in the Gear selector.

2. Check the fluid yourself!.

3. Change the Fluid (sometimes fixes shift problems, and the car will definately shift much smoother)

4. If it is the RPM sensors , then get it repaired. Otherwise get an exchange transmission (very expensive). If you are mechanically inclined , use my DIY. Given access to a car lift and support stand, it is a simple 6 hour job!

5. Don't buy an older used transmission. There were considerable design improvements (lessons learned from numerous failures on MY98/99 models).
Make sure you get exactly the same transmission that matches your engine ... They are specific to engine sizes , adn cannot be mixed (electronics control the shifting differently).

 

MB say that the fluid is "filled for life". This is total BULL****!. It is so rediculous that even MB dealerships are changing their customers transmissions fluid every 40k KM.

See gillies report on this.

http://www.mercedesshop.com/shopforu...ht=722.6+gilly

 

My DIY is on the P3 forum.

w w w . p o i n t e d t h r e e . c o m

 

I took it to the dealer. It's supposedly the ABS control module. It is covered under my extended warranty.

Also, the catalytic is sounding, dealers says it's $1102.00 to replace. The extended warranty doesn't cover it. I thought there was a recall on that? I have 93,000 miles, it's a 2000.