722.6 Erratic Shifting Problems Solved - PeachParts Mercedes-Benz Forum

Southern · #1 09-30-2008, 07:21 PM

My 1998 E320 currently has 155K miles. Last year I had the car in the dealership to have new spring perches installed. While the car was in the shop (first time since I owned the car at 58K miles) they told me that the trans seal was leaking. I authorized the work since I was aware of this problem. When I picked up the car the invoice stated that they added transfluid. When I go home I checked the trans fluid level and it was low so I brought it back to the proper level.

Prior to this the car would have it's moments when shifting. When I punched it it would slam into gear. When I would accelerate moderate to heavy and maintain the gas peddle the car would go into neutral for a second as it was shifting from 3rd to 4th gear. When I didn't come to a complete stop and started to accelerate the car would jerk forward. Other then the above erratic problems the car shifted fine.

After researching this problem on the MercedesShop forum I read posts that suggested that the trans connector could have taken in some oil. I assumed that this was the connector at the transmission end but another thread pointed to the connector at the TCM. I figured that it was highly unlikely that the trans fluid would work it's way from the transmission to the TCM.

After removing the connector yesterday I was proven wrong. Below is a few pictures showing the trans fluid on the connectors:

http://www.peachparts.com/shopforum/attachment.php?attachmentid=59610&stc=1&d=1222816207
http://www.peachparts.com/shopforum/attachment.php?attachmentid=59611&stc=1&d=1222816279

As I started cleaning the connectors I noticed that trans fluid was leaking out of the TCM as I inverted it. So I popped the circuit board out of the plastic housing and here is what I found:

http://www.peachparts.com/shopforum/attachment.php?attachmentid=59612&stc=1&d=1222816451

So much for "sealed for life". There must have been over 2 tablespoons of trans fluid in there.

After cleaning up the circuit board and connectors the board looks like new again:

http://www.peachparts.com/shopforum/attachment.php?attachmentid=59613&stc=1&d=1222816579

I ended up cleaning up the board and connectors with brake disk cleaner. It is non-flammable, safe on plastic, cuts through oil and evaporates quickly.

After driving my car to work today, the transmission shifts normally again thanks to all you contributed to the various posts about the trans fluid on the TCM connector.