1998 E320 won't engage into gear when car warms up. - PeachParts Mercedes-Benz Forum

BENZ TEK · #1 01-30-2013, 10:13 AM

Hello all. I have a 1998 E320 that will not engage into reverse or drive once the engine starts building some temperature. I checked for codes in the transmission computer but the last shop erased them before the car got here. This is what I found so far. The transmission computer had fluid in it so I cleaned and dried it out. The adapter plug was also wet so I changed that also. Neither of those items fixed the problem so I went into live data and found that the transmission does recognize the shifting thru the range from park to drive when the car is cold. When the car is hot, live data shows me moving from park to reverse and drive but the actual gear will not match up. I think I may have a bad conductor plate in the transmission but I'm not sure. Any help would be much appreciated!!

97 SL320 · #2 01-30-2013, 08:05 PM

The 722.6 defaults to 2nd and will still have reverse if the electrical system goes down.

Shifter position is referenced by a switch on the shifter in the car.

A clogged inlet filter can cause this but the debri has to come from somewhere. . . .

A large internal leak / worn pump can cause this, if there it a line pressure tap on the trans that would be a good place to start testing.

Southern · #3 01-30-2013, 08:22 PM

It could be a separate problem, sounds like the shifter electronics might have got wet (spilled drink, sunroof left open).

BENZ TEK · #4 01-30-2013, 08:27 PM

I think the issue is electrical. When you watch the live data feed shifting from park to reverse it syncs up correctly. When the car get hot both indicators show park but when you move the gear shifter the no longer sync up. When cold you will have P=P R=R N=N and D=D when the car gets warm you have P=P R=N N=N D=N. so the transmission stops recognizing the correct position of the shifter. Not sure if its the conductor plate or not.

Southern · #5 01-30-2013, 08:40 PM

The shifter assembly is electrical with wires going to the trans computer. Another problem with older W210s is that the shifter bushing gets worn causing slop in the shifter.

BENZ TEK · #6 01-31-2013, 08:06 AM

I checked the bushings and they are fine. No play or slop in the linkage. I am going to take a shot an change the conductor plate. Hopefully that will fix it. I will let y'all know of the outcome. Thanks everyone for the advice.

TimFreeh · #7 01-31-2013, 08:56 AM

I don't think the conductor plate plays any role whatsoever in determining/recognition of transmission drive range. That's a conversation that occurs between the transmission ECU and the shifter. Seems like the shifter and the trans ECU are not communicating properly.

TimFreeh · #8 01-31-2013, 10:44 AM

On second thought there is a reed switch that is mounted on the right side of the plate that indicates if the car is in Park? Maybe the reed switch is malfunctioning and confusing the gear selection logic in the ECU?

As I recall the transmission fluid temp sensor is wired in series through the reed switch and will only provide temperature data when the car is in drive or reverse? To check the reed switch you could monitor the transmission temp via live data while shifting the transmission from park to drive. If the switch (and wiring) is working correctly you should see the temp value change when the transmission is shifted into gear.

BENZ TEK · #9 01-31-2013, 01:48 PM

Thanks Tim. Let me try that first.

mespe · #10 09-03-2013, 08:18 PM

Outcome?