722.6 transmission issues, P2500, P2502, P2503, P2222
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Joined: Feb 2019
Posts: 13
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2001 ML55 AMG, 2003 CLK500, 2003 C320 4matic, brabus monoblock IV 18”
722.6 transmission issues, P2500, P2502, P2503, P2222
I currently own a 2003 CLK500 coupe (purchased for the beautiful blue interior) that I’ve owned for about 2 years, but haven’t driven much. Few thousand miles, as I currently daily my lifted ML55. The car drove great upon purchasing… for a while, until it recently started having trans issues.
important note, the car currently has 74k TRUE MILES
trans codes
P2500: transmission has impermissible transmission ratio
P2502: The gear is implausible or the transmission is slipping.
P2503: gear comparison is negative or target gear not reached
P2222: signal of component Y3/6b1( Transmission oil temperature sensor) and(or) Y3/6s1( Starter lockout contact) is implausible
I’ve owned plenty 722.6 cars, and have found them to be relatively bulletproof, with most issues being derivative of electronic part failures. So I assumed the same for this case.
Symptoms began with slow/jerky shifts. Assumed it was the trans plug, got that replaced. Drove fine for a while, problem persists. Eventually, the car began getting stuck in 1st gear. Turning the car off and on always fixed this, though once it started doing this, it began doing it frequently. Again at the same time, it progressed by beginning to slip gear and free rev anytime you put your foot on the gas, typically in 2-3rd gear shift.
When the car free revs, it seems to be partially in gear, as it will allow you to (very slowly) accelerate at very low RPM, like +1 mph ever 2 seconds. But try to give it any more than 1900-2k rpm and boom, slip and free rev. 1-2nd still has noticeable lag, but don’t seem to slip.
Got a trans service, only code shown was P2500. Got fluid, filter, gasket, etc. Old ATF was very dark brown-red, with some aluminum shavings.
Weird thing is, the valve body was quite rusty… car does not seem like a flood car, possibly radiator fluid contamination??? (Waiting on the photos) Also, based on threads concerning this contamination by a faulty radiator seems like it happened fairly early on in these vehicles lives, and were typically addressed early.
I have also checked the TCM in the footwell for the heck of it. Had an oily smell/residue, but didn’t seem to be anything of concern, visually it looks clean/not oily.
Does this seem like the time for a replacement trans (after the radiator is checked and replaced if bad)? I truly did not expect to have serious mechanical issues with a 722.6 on a 74k mile car.
important note, the car currently has 74k TRUE MILES
trans codes
P2500: transmission has impermissible transmission ratio
P2502: The gear is implausible or the transmission is slipping.
P2503: gear comparison is negative or target gear not reached
P2222: signal of component Y3/6b1( Transmission oil temperature sensor) and(or) Y3/6s1( Starter lockout contact) is implausible
I’ve owned plenty 722.6 cars, and have found them to be relatively bulletproof, with most issues being derivative of electronic part failures. So I assumed the same for this case.
Symptoms began with slow/jerky shifts. Assumed it was the trans plug, got that replaced. Drove fine for a while, problem persists. Eventually, the car began getting stuck in 1st gear. Turning the car off and on always fixed this, though once it started doing this, it began doing it frequently. Again at the same time, it progressed by beginning to slip gear and free rev anytime you put your foot on the gas, typically in 2-3rd gear shift.
When the car free revs, it seems to be partially in gear, as it will allow you to (very slowly) accelerate at very low RPM, like +1 mph ever 2 seconds. But try to give it any more than 1900-2k rpm and boom, slip and free rev. 1-2nd still has noticeable lag, but don’t seem to slip.
Got a trans service, only code shown was P2500. Got fluid, filter, gasket, etc. Old ATF was very dark brown-red, with some aluminum shavings.
Weird thing is, the valve body was quite rusty… car does not seem like a flood car, possibly radiator fluid contamination??? (Waiting on the photos) Also, based on threads concerning this contamination by a faulty radiator seems like it happened fairly early on in these vehicles lives, and were typically addressed early.
I have also checked the TCM in the footwell for the heck of it. Had an oily smell/residue, but didn’t seem to be anything of concern, visually it looks clean/not oily.
Does this seem like the time for a replacement trans (after the radiator is checked and replaced if bad)? I truly did not expect to have serious mechanical issues with a 722.6 on a 74k mile car.
Thread Starter
Newbie
Joined: Feb 2019
Posts: 13
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2001 ML55 AMG, 2003 CLK500, 2003 C320 4matic, brabus monoblock IV 18”
that was my thought originally, but the local indie pulled the valve body when doing the trans service, and stated the conductor plate was fine. There was also substantial rust on the valve body itself, which I am still at a loss for how that would happen.
will DAS scan be able to tell if the conductor plate is faulty? Or will it continue to be a guessing game replacing parts?
I can get a 90k mile trans with 6 months warranty delivered and installed for $1300 all said and done. Shop will drop the pan and make sure all is good.
that is my predicament, try replacing part after part to see if that fixes the issue, or just drop in a whole new unit.
will DAS scan be able to tell if the conductor plate is faulty? Or will it continue to be a guessing game replacing parts?
I can get a 90k mile trans with 6 months warranty delivered and installed for $1300 all said and done. Shop will drop the pan and make sure all is good.
that is my predicament, try replacing part after part to see if that fixes the issue, or just drop in a whole new unit.
MBWorld Fanatic!
Joined: Jan 2014
Posts: 3,967
Likes: 1,315
From: Republic of Texas
'99 and '05 E55 AMG
The codes indicate a failed conductor plate or bad clutch packs slipping in the transmission; if clutch packs are bad should be noticeable with RPM flares between shifts. Yours is a low-mileage transmission and s**t happens but I discount bad clutch packs. My car is at 240K miles and clutch packs are finally beginning to reach the end of acceptable engagement values. Yours would have to be failing very early and possible if you had a 2003 model with the radiator that leaked coolant into the transmission fluid and dissolved the friction plates
FWIW, if me, I would go for a new conductor plate as the least expensive option. If not, a full rebuild by Southern Hot Rod in Kenner, Louisiana, for $6200.
Does the used transmission guarantee cover the labor, the towing, the rental vehicle, and your time dealing with a failed "guaranteed" used transmission? Or do "they" just send you another transmission and you suck up the costs?
Your circus, your monkeys. I've been there multiple times and have the T-shirts...
Edit: DAS/Xentry can read transmission health; pressures, solenoid response times, clutch and brake pack engagement times, etc. Good diagnostic tool.
FWIW, if me, I would go for a new conductor plate as the least expensive option. If not, a full rebuild by Southern Hot Rod in Kenner, Louisiana, for $6200.
Does the used transmission guarantee cover the labor, the towing, the rental vehicle, and your time dealing with a failed "guaranteed" used transmission? Or do "they" just send you another transmission and you suck up the costs?
Your circus, your monkeys. I've been there multiple times and have the T-shirts...
Edit: DAS/Xentry can read transmission health; pressures, solenoid response times, clutch and brake pack engagement times, etc. Good diagnostic tool.
Last edited by bbirdwell; Dec 10, 2024 at 08:32 PM.
Thread Starter
Newbie
Joined: Feb 2019
Posts: 13
Likes: 2
2001 ML55 AMG, 2003 CLK500, 2003 C320 4matic, brabus monoblock IV 18”
I really appreciate the advice, this is why I’m here. Conductor plate was my first thought based on symptoms, but seeing the rust on the valve body once the trans was opened up scared me a bit… I typically do most of my own work, but thus far all the 722.6 cars I’ve owned have been relatively low mileage, so I’ve never had issues further than the trans plug.
Luckily this isn’t my daily, so I don’t have to worry about transportation for the time being. Bought the CLK for better gas mileage on longer drives, as my ML55 on 33” A/T’s absolutely drinks fuel. The fact of the matter is I am simply trying to sell the car, and of course as soon as I get a bite, the car decides to act up. I am moving in ~6 months and will be bringing the ML and hopefully will have this car gone by then. Don’t wanna be a total POS and hide the issues to pass off to the next guy without getting it sorted/driving right again.
Gonna go ahead and see about find a shop with STAR to see if that might tell me anything if pricing is reasonable. Been looking to buy a system for years but have been able to accurately diagnose via carsoft thus far so I didn’t bother. Kicking myself for that, I’ll be ordering a kit soon.
Luckily this isn’t my daily, so I don’t have to worry about transportation for the time being. Bought the CLK for better gas mileage on longer drives, as my ML55 on 33” A/T’s absolutely drinks fuel. The fact of the matter is I am simply trying to sell the car, and of course as soon as I get a bite, the car decides to act up. I am moving in ~6 months and will be bringing the ML and hopefully will have this car gone by then. Don’t wanna be a total POS and hide the issues to pass off to the next guy without getting it sorted/driving right again.
Gonna go ahead and see about find a shop with STAR to see if that might tell me anything if pricing is reasonable. Been looking to buy a system for years but have been able to accurately diagnose via carsoft thus far so I didn’t bother. Kicking myself for that, I’ll be ordering a kit soon.
Thread Starter
Newbie
Joined: Feb 2019
Posts: 13
Likes: 2
2001 ML55 AMG, 2003 CLK500, 2003 C320 4matic, brabus monoblock IV 18”
So, read a post on here saying the trans operates more mechanically under WOT than during regular driving. Tried giving her the beans, and… what do you know, buttery smooth shifts 1-4. Tried in manual mode, same thing.
It still acts strange, as soon as throttle is let go, it refuses to upshift… only wants to change gears under WOT. Once I let off the throttle, it tends to get stuck in whatever gear it is in. Sometimes it will kick into gear (roughly) once speeds have slowed to ~20mph, sometimes gets stuck in that gear until the key is cycled.
Also, the trans kicking into free rev seems to be RPM dependent- after WOT, the car remains at high rpm in the gear it is in, and any throttle modulation and the car accelerates as it should. When the car is in low rpm range though, any throttle modulation causes free rev. Seems like this is primarily an issue in the ~2200-3500 rev range?
On a particular stoplight there was a VERY harsh downshift resulting in tire chirp while coming to a stop. Car was stuck in 4th(??) gear, and at about 20 mph it kicked down hard, causing the car to lurch and lock up the rear wheels for a fragment of a second.
Trying to provide all data/observations i can, that’s the scientist in me
It still acts strange, as soon as throttle is let go, it refuses to upshift… only wants to change gears under WOT. Once I let off the throttle, it tends to get stuck in whatever gear it is in. Sometimes it will kick into gear (roughly) once speeds have slowed to ~20mph, sometimes gets stuck in that gear until the key is cycled.
Also, the trans kicking into free rev seems to be RPM dependent- after WOT, the car remains at high rpm in the gear it is in, and any throttle modulation and the car accelerates as it should. When the car is in low rpm range though, any throttle modulation causes free rev. Seems like this is primarily an issue in the ~2200-3500 rev range?
On a particular stoplight there was a VERY harsh downshift resulting in tire chirp while coming to a stop. Car was stuck in 4th(??) gear, and at about 20 mph it kicked down hard, causing the car to lurch and lock up the rear wheels for a fragment of a second.
Trying to provide all data/observations i can, that’s the scientist in me
