mldisappointed

My 2002 ML500's transmission has recently acquired a mind of its own.

About 50% of the time it will only let me have First or Reverse at startup. HOWEVER, by parking the car, turning it off, and restarting it, if OFTEN (say 90% of the time) will start behaving normally. Sometimes I have to repeat this process several times to get it to wake up.

I've tried disconnecting the battery and reattaching it (with the idea that the computer was in need of resetting).

The car has a little over 65000 miles on it, and has had the B service.

Other problems (while we're at it):

Noisey fuel pump. Pump has just started making a loud whining sound (was very quiet prior to this). Checked the fuel cap, seems air tight. Fuel filter was replaced about 6000 miles ago (though with the maroons at the local dealer, this may not be a good thing). Noise is intermittent - more common after the truck has been warmed up and run for a while. No driveability issues (other than tranny issue noted above). Was there a recall for fuel pumps?

The Dolby audio head replacement (twice - the last one just before the end of the warranty) for volume fluctuations. This third one is now starting to demonstrate the same erratic behavior.

The truck went through 3 sets of pads in the first year (incl. originals of course), including resurfacing the rotors each time, with 1 set under warranty (Dealer insisted I pay for the third set as "normal wear and tear"). Next set wore out at 35,000 miles, Dealer installed another and warned me that new Rotors would be needed next time. I installed a set of MB pads myself at 50,000 miles, noted that the rotors were deeply worn - rotors WERE, indeed, almost worn out. Brakes ALWAYS squeaked by the way, day 1 until I lost patiance with Dealer.

I solved problem with new Brembo rotors, ERG green pads, and antisqueal compound when I installed new front brakes personally at 60,000 miles. First time the vehicle has not had noisey front brakes. I am about to repeat the process on the rears (which are, of course, still squealling at this time).

Common Issues I have personally fixed:

Coolant smell (rerouted overflow/vent hose with 18" extension - worked fine)

Washer fluid leak (epoxy fix)

Seat trim cracked (yelled at dealer until they fixed this problem for third time under warranty, now cracked again, now epoxied and ignored)

EGR valve and tube (trying to find parts - dealer says they are on backorder for last 2 months) Check Engine light now on. (Wonder if this has effect on fuel pump?)

Any help will be greatly appreciated. I am a moderately experienced mechanic, and having despaired of the lousey service at the dealers, I am now training up on ML's. I suspect the tranny has its own software/brain, and that it is losing its mind.

MBTech21

The most common problem with these trans modules is they fill up with oil- the electrical connector on the trans leaks and the fluid migrates up the harness into the module. Usely, change the plug on the trans, clean the harness out with brake cleaner, and the trans module (let dry over night) and should be good to go. In some cases, module is fried-sorry!!
No recalls on pumps, they get noisy sometimes, it's an electric motor- may die tomorrow, may last 5 years like that.
Sounds like you have had some issues...hope this helps...

mldisappointed

Helps a great deal (I had considered the idea that a coke had been spilled and done essentially the same thing).

I am in your debt. I suspect you are EXACTLY on the money. Another kind soul also has told me I probably should reset the ECU and change my fluid - all good ideas I think.

If the dealer was as helpful and knowledgeable as the folks on this site, I would have had a much better owner experience! I should have started doing my own maint. long ago.

C32AMG/02

A defective stop light switch ( brake switch) will prevent you from moving the selector lever with a touch shift lever. Check all modules for any codes

mldisappointed

I suspect the module is now full of fluid, for the ML will only give me first and reverse.

I am getting A Check Engine light, but my OBD reader says "No Trouble Codes".

Have just replaced the battery (dead), hoped that would help, but has no effect.

Where is the module located that is soaking up all the fluid, and how do you get to it? I have attempted to buy a shop manual for this truck, but Mercedes seems determined to prevent it.

If anyone has good pics and brief rundown to get the module in and out, I would really appreciate it.

It may also be that the Brake Switch that was mentioned is at fault - though would this prevent normal "D" functions as well as the manual shifts?

Thanks for all the help!

SUNILP

if the brake switch was bad:

a. the brake lights in the rear won't work (check those)
b. there would be other error bulbs such as ABS

mldisappointed

Brake lights work fine.

No other error lights.

Thanks!

mldisappointed

Gave up and have driven car in First gear (limp mode) to the dealership.

$100 worth of diagnosis coming up.

Will post results. I am betting its an electronic problem, but NOT the ETCM, but a switch or sensor located elsewhere (with my luck, deep within the transmission, requiring $1200 worth of labor to change ten cents worth of plastic switch).

Will advise...

MBTech21

Sorry, didn't have time to answer your post- the module is mounted under the drivers side underpanel- up next to the heater box. As far as anything electirc in the trans- there is nothing past the valve body, so it can all be done 'in-car' and hence, not more than a few hundred in labour usually. Let me know what they say..

mldisappointed

I expect to know today - the tech I spoke with yesterday doubted it was the ETCM (possible but rare is how he put it) - he seemed to think a drink spilled on the shifter console might have gummed up the switch or fried a connection (I'm sure my wife has had some spills, so this sounds possible to me).

Will advise. Thanks for the hand-holding. I'm trying a new dealer.

My last experience with the old one was unpleasant, involving work performed but not authorized (in fact, I wrote on the drop-off order specifically to call before performing any brake work, since I intended to perform that work myself). Got into a huge argument that it was a safety issue and they had done the work as a 'favor' to me. Of course, the "favor" was setting me back $1200, not counting the brand new parts sitting in my garage which I had purchased to do the work myself! Sevice manager also informed me that shade tree mechanics (I'm a professional industrial engineer, with 25 years experience) using substandard parts (brembo rotors and EGR pads) would just mess up the job anyway. I documented the whole thing and shot it off to the owner, who replied with a form letter about how much he valued my business.

There are two dealers in Atlanta. Stay away from the one that has a "C" in its name. I'll let you know how the other one works in just a little while...

mldisappointed

You were correct about it being the ETCM - new one on order (hopefully will come in tomorrow). Price:

$100 (appx. - diagnosis)
595 (ETCM)
50 (installation labor)
100 (reprogram)

$845 plus tax - out of my pocket, unfortunately.

They also spotted cracks in the catalytic converters, and those are being replaced under warranty.

Your advice and knowledge is greatly appreciated.

Afraid I'm still "mldisappointed". This car has been one constant headache. Next item (just put new battery in, by the way) is the car's third set of tires (forget Dunlops!). I'm trying Hankooks this time (higher wear rating than the Dunlops, cheaper price). I never liked the Dunlops (noisey, and short life spans) anyway.

Thanks again.

mldisappointed

Final tally went higher (what a non-surprise). $1014 including tax.

Turns out they spotted cracks in both catalytic converters (replaced under warranty), and a melted heater hose that had worked loose somehow. Anyone used to buying heater hose for a couple dollars a foot should avoid letting a Mercedes dealer charge them $72 for one. You can buy the identical item at any parts store for less than $8 or $9. (Assuming you can't avoid melting yours while working on your exhaust).

Atlanta Mercedes dealers are batting "000". Consistent, though.

Only dealership I've ever visited where you had to wait over an hour before anyone could take your order for work - guess its like some restaurants where they are empty but park you in their bar for an hour so you can buy some overpriced drinks. Here they park you in a waiting room surrounded with Mercedes accessories (with several sales clerks willing and able to sell you anything you want, so long as it doesn't have anything to do with fixing your car).

Bizaare.

Thanks to MBtech21 for all the help - I owe you one.