Help, I know nothing! Trans Toast?
 

I took my 99 S320 (109,000) in for CA smog and it passed great, with no problems. On the way home the trans began to slip a bit and then it went into limp mode. I got the car towed home. My check engine light is on and the code read P0763.

I took it to a local Mercedes shop and they told me they think the transmission is toast and that I should have been changing the fluid every 40K. I told them I thought it was a lifetime fill. They said no there have been too many problems. They say the dipstick fluid looks black and the only computer codes they are getting are from the trans. ($98.50 diagnosis).

They want to replace the trans with a rebuilt $3700 plus $800 labor. Does this seem reasonable? Should I consider towing for a second opinion? I doubt the car is worth much more than $10K . Just nauseus right now.

Thanks for any knowlegable advice . chris

get another diagnoses first.

george

If they pointed to the black fluid as a sign of a transmission problem it would be time to look for another shop.

cemii -

The code 'P0763' is for 'Shift Solenoid C Electrical'. I'm no tech, but that seems like it could be an electrical part failure in the tranny (solenoid). I would imagine the part is relatively cheap and could be replaced within a few hours. Perhaps add the charge for a new sealant/fluid and maybe you are looking at a few hundred bucks.

Bring it to a shop that KNOWS Mercedes.

Good luck.

Get a second opinion.

Call a local dealer or two and find out who THEY send their trans to for repair and go there.

Here is an old write up from "Gilly" (a respected tech and past moderator) regarding teh 722.6 trans. You do need to change fluids. IMO 60k is prob OK. Use MB fluid for the 722.6, or the newer backward compatible 722.9 (G-Tronic 3353) MB fluid only.

http://www.peachparts.com/shopforum/702285-post8.html

Terry, I am also in the Walnut Creek area. If you have any recommendations on service places, i'd appreciate leads. The place i took it is "German Sport", behind Midas on Autocenter dr. off north main. I need to either get it out of there on monday or authorize the work. Any recom. for second opinion? Stead is my only thought.
I'm very thankful for everyone's input.
chris murphy

Get your car away from there. Many of these transmissions are misdiagnosed because shops have not made the transition from dealing with vacuum controlled to electronically controlled transmissions. If the code says "shift solenoid electrical" then it is pretty certain that it is indeed an electrical and not a mechanical problem. This could be further diagnosed without disassembling anything, provided the shop has the correct diagnostics equipment and is actually willing to use it.

Diagnosing the 722.6 transmission is no big deal. The first step depends on the fault code(s) retrieved. In this case there are two options, depending on the test equipment that's available. The solenoids are located in the valve body and can be activated with SDS. The resistance of each solenoid can also be checked with an ohm-meter from the connector at the control unit. Personally, the first thing I would do, would be to check the ECU to see if it's full of ATF. If the ECU is clean, the solenoids can be tested right from the connector. The resistance values can be found in the Web ETM, available at all MB dealers. Serious indies' who subscribe to Startekinfo also have access to this information. This test only takes a few minutes. Also, at 109K, the pan should be removed to check for signs of internal damage.

I can't overstate how helpful SDS can be in diagnosing 722.6 transmission issues. My advice is to let a dealer check it out. An independant shop equipped with SDS and MB transmission experience would be a good alternative if you're not crazy about the dealer. Good luck

First check the TCM, Transmission Control Module for Tran’s fluid contamination, passenger side rear fender by the fire wall, black box. Look at the wires on the controller (SIEMENS EGS) if you see fluid on the wires that’s your problem.


A while back I posted the complete test For the TCM voltage and resistant test thru the TCM, I did an search and can not find it, maybe you will have better luck than me.

The last thing that happened before the transmission acted up was you had the smog test done. Is that test done on a chassis dynamometer in California? If so, did they disengage the traction control first? I am not sure the car would turn the rear wheels in that situation without disengaging the traction control, but maybe the transmission control unit is confused because the rear wheels were turning and the front wheels were not.

Update: I called AAA for a tow to the dealer. The T/T driver told me he knew a great MBZ only shop a couple blocks away and they would be way cheaper than the dealer. I took it there and they also told me trans was toast ($120 analysis; $5350 estimate on a rebuilt). They, of course badmouthed the last place I took it.

Well, know I'm really confused and feeling really stupid for listening to the T/T driver who may have had a vested interest or not, so I guess I'm going to try a third opinion at the dealer. I'm getting stubborn now and it's the only way I'm going to get an SDS opinion. But then what, I still don't really have faith in either of the two shops I've visited.

Since there are many other small cumulative small shortcomings with the car (tires, rims, 2 rock chipped headlights and a windshield bullet chip, non working auto aerial, window activators weak, etc) I am closing in very quickly on net deducts from FMV that are fast approaching a big zero. It may be time to think about a headstone!

i'll update again after the dealer with whatever the next quantum leap is, just to update for all who have been so very helpful and to reaffirm how lucky you are to know what you're doing.

I also thought it was interesting that neither one of these two MBZ shops would have thought that it might be necessary to turn off the car again in limp mode to get it to engage from R to FWD as I had learned from pure trial and error. Both pushed the vehicle into their shop. But maybe this is unusual and only particular to my problem?

Can anyone lead me to a resource that would tell me which other Mercedes yrs./models used the same 722.6 as my 99 320S. This just so I can look at a potential junkyard swap as an alternate though i recognize the risks inherent.

The 722.6xx started showing in late 97 I believe.

Do mention to the dealer your problems began when the car was on the dyno getting a smog test. THat point seems quite relavent.

My gearbox fluid was as black as diesel oil when I changed it, and that was done at 168,000 miles.

http://homepage.ntlworld.com/tom.jef.../old%20atf.jpg

You have good advice above, before you spend any money, follow it. The gearbox electrical connector is a good place to start, when those seals fail the ATF will wick its way up the cable and into the ECU, making a right mess of things (although it can be cleaned and restored 100% with alcohol or lighter fluid).

Oh, and changing the ATF would be a very good idea. Get yourself a dipstick, and read this:

http://forums.mercedesclub.org.uk/showthread.php?t=25566

follow
 

i did get a code printout and can make a pdf of it attached, but i don't understand