This is one for the techs - MBDOC, Gilly. Larry - PeachParts Mercedes-Benz Forum

Will_w202 · #1 07-21-2005, 09:51 PM

97 c230 - ongoing trans issues - however seemingly minor from time to time - since purchased in 3/04, 30k miles ago. Car has 90k. Symptoms have changed over time. Initially I had a first gear hesistation, but I think that was tied to something else (can't remember) that was fixed. Nonetheless, fluid and filter changed at 65k, new conductor plate, electronic "board" replaced TWICE for erratic shifting, shifter bushings just done as well.

I have 2 issues that I SWEAR are tied together, but even my indie says not.

First, the shift lever itself, when first shifting into D after tha car has sat for a few hours, has very sloppy "lockage" into D. It will move up and down within the D slot. The other condition is, even after 2 elec. boards and conductor plate, is that sometimes the trans will star out on 3rd gear, or slam into another gear. VERY occasional, so much so that it cannot be reproduced when the dealer has the car. BUT IT IS THERE. AND, this only seems to happen when the lever has play in it. If I throw the lever in P, and shift back to D a couple times, it seats properly. Bushings were just replaced and it STILL does this. I think I have a serious trans issue and I have 7k left on my warranty. The shop foreman keeps mis-diagnosing it. What is the issue???

Again, this only sems to happen when the lever isn't seated, but Indie says the lever would have to be notched clearly into another gearslot for this to happen - he thinks failed spring in valve body or TCM - ideas?

whunter · #2 07-22-2005, 12:29 AM

Sounds like a bad shift lever, transmission or engine mounts.

Is the shift lever arm (in console) going up/down and/or rotating???

joeym · #3 07-22-2005, 05:36 AM

Hi Will You might be having a problem with the EGS trans control unit,or they did have a problem on your veh with a one way roller bearing it would hang up cause shifting problems and thumping I would have a good shop with a up to date tester go in check the wear limits,call the dealer with the trans # and see if the TB applies to your trans,when coming to a stop some times you will get a thump like some one hit you from behind.joeym PS was the valve body checked for an update when the replaced the conductor plate

mbdoc · #4 07-22-2005, 08:10 AM

Follow "joeym"'s advice!

IF the trans has problems WHAT codes are being read from the trans computer??

The trans computer is adaptative. IT also stores info of the transmissions ability to take the POWER (torque) from the engine. THAT info can be read with a MB scanner & even printed out! HAVE someone with that type of scanner read the "shift adaptation" values from the trans computer. IF they are near OR at max amount GET the transmission replaced.

Will_w202 · #5 07-22-2005, 07:14 PM

Thanks a ton guys, I will have this all looked into. It does indeed thump when coming to a stop, and always has. I'm taking it to my dealer's sister service dept for a fresh perpective. I also plan to pay my indie for a full going-over at about 97-98k.

Gilly · #6 07-22-2005, 08:48 PM

I would think in terms of checking out the shifter to find the cause of the looseness, it's a bit of a head scratcher on why it only is like this occasionally.
If the "board" that was replaced is the transmission control unit (ETC), you also need to know that these are paired with the valve body and they have to match. Someone may have sold you/them a control unit which no longer matches your valve body, this should be investigated.
Back to the shifter, yes it should be taken out. There was a part which routinely failed in this era called the "range recognition switch" and if it was replaced, on these slightly older ones it was a puzzle to tear down and replace this switch and reassemble it all properly.
On the 722.6, the sifter mechanically shifted only to park, reverse, neutral, and drive. The last ranges were done electronically via the range regognition switch, all you do by pulling back past "D" is to change this switch, the shift rod is NOT moving. So sounds very much like your concern may be related, although still you should start out in first from a stop, but who knows?

Will_w202 · #7 07-25-2005, 02:36 PM

Interesting. Now, I have to decide if I tell the MB shop foreman, and have him pissed at me for secind guessing him or knowing too much, or continue to play dumb and hope they find the right fix.

Suggestions guys?

On a side note, the behavior has become more predictable. It only displays this sloppiness after sitting for a while. Every day in the last week, when I crank the car and put it in drive after it has sat at least a few hours, it will be loose in D. Once it's been shifted back into P and out of D again, it is ok until the cycle of sitting is repeated. Also, it has been erratic every time the shifter does not seat. Today, it started in 3rd, slammed into 3rd later, and would not shift out of 2 until I jiggled the knob. I took it straigh to the dealer and the foreman looked at it and write down my VIN, saying he would be in touch. He also asked if the TCM had ever been replaced. Even if they put one in now, it won't fix the shifter, and it IS related.

Shop forman REALLY seems perplexed when I bring the car in for this issue.

mbdoc · #8 07-25-2005, 04:55 PM

There has to be a code in the trans computer! and The computer must store the self-adaptation of every clutch pack. IF not, then the pressure regulator spring(in the valve body) may be broken!

Will_w202 · #9 08-08-2005, 03:29 PM

After 3 days of diags, which I was told consisted of shop tests and road tests, both hooked to the laptop, the shop foreman has conferred with MBUSA and they both agree the car will get a new TCM.

Now, I have thought, based on erratic shifting since purchase, that the TCM was flaky. But what the heck does a TCM have to do with the physical position of the shifter itself? Not much I would think!

Oh well, baby steps I guess, right?

Gilly · #10 08-09-2005, 04:30 AM

It wouldn't have anything to do with the looseness of the shifter. The erratic shifting yes, but not the shifter being loose.
Gilly

Will_w202 · #11 08-14-2005, 10:17 AM

Well, they replaced the TCM. VERY interestingly, the shifter has not been "hunting" for the "D" gate as often, though it STILL occasionally doesn't want to seat all the way firmly until I re-shift it. Observations:

Since the new TCM was installed, the upshifts are much quicker - snappier - is this normal?

Secondly, this morning, it absolutely slammed into 2nd gear from 1st - it's usually from 2-3 - and shook the whole car.

I just want this fixed under warranty! They have replaced nearly EVERYTHING over 30k miles except a valve body, the entire shifter setup, and the transmission assembly itself. I'm at 93k. I've got 7 for MB to figure this out, and right now, I"m losing confidence. This last diagnosis came with 8 days of work, including the shop foreman speaking with MBUSA on the issue and cause. Oh, and this marks the 2nd time I have asked for adaptation values. They give me the runaround, sayign they didn't save them. Last time, it was that they couldn't give that info out.

What is causing this?

Moneypit SEL · #12 08-14-2005, 10:48 AM

I don't have a clue as to the problems, but I just wanted to say that you likely will be able to force MB to eventually fix this, even after the warranty expires. You have a well-documented history with this problem, and it's not your fault that they've taken so long to not fix it. I'd take it back, tell 'em to fix it, and don't bother me until it's fixed.

Will_w202 · #13 08-30-2005, 01:42 PM

Well, took car to sister dealership for a fresh perspective, and to add to the new trans computer, they diagnosed it as a problem in the shifter itself. So, I got a new "floor shift mechanism" and "selector module."

But when I drove it off the lot, it did the same thing!

I brought it back inside, where I noticed someone had also hit the car against something on the back lot apparently, causing a bend on the rear-door pillar by the quarter glass. They did light body and paintwork to it - ugh - but it looks fine now, and I'm ok as long as they didn't have to paint the whole panel.

Anyway, the foreman himself worked on the car, and found a loose screw on the shift rod at the transmission - so, for a loose screw, I got a new TCM, shift mechanism, selector module, and 3 qts of trans fluid (and some light body damage)

In their defense, my shop guy said he had NEVER seen this happen before, and has no idea how the screw became loose.

SO, the loose screw was causing the lever to not seat into "D" fully, and because the shifter was out of position and moving ever so slightly while I was driving, confusing the electronics.