I bought this coupe last year and stored it inside a SeaCan over the winter. I got it out and had no issues and THEN... out of town, I drove to Timmins and as I stopped at the stop sign before turning onto 101 to go into Timmins, it HARD SHIFTED and went into Limp Mode! I pulled over and turned the car off. I sat and let it rest for about 5 minutes and then started it up. The Check Engine Light was on and I drove it with my Hazard lights on and in Limp Mode into Timmins. I had noticed a couple of times on previous trips that when I pulled out onto the highway and I got up to 100 kph that the rpms were at about 3500. I pulled over and turned the engine off and let the tranny settle for about 2-3 minutes then restarted it and got back up to 100 kph and the rpms were a normal 2400. I have to think that the Hard Shifting and the tranny not making the gear change into top gear must be related! I'm assuming the high rpms were because of it not changing gears.
I took it to the local Dodge-Chrysler dealership but they said they were way too busy and wouldn't be able to see it for 2 weeks! They recommended a local shop which is where it is right now! I dropped it off 2 days ago,.
If any of these symptoms sounds familiar, please reach out!
Cheers

 

1. Don't go to a Chrysler dealership with your Crossfire. They stopped servicing the Crossfire years ago and the fact that it is a Mercedes R170 their techs do not know a thing about it.
2. Best place for service is an independent shop that specializes in European autos with an emphasis on Mercedes.
3. Do you have any maintenance records for your Crossfire? When was the transmission fluid changed?
4. The shop you use must be able to use a scan tool to get into the Mercedes transmission codes; Scan as a 2004 Mercedes SLK 320 if your car is a Limited model. The DTC will tell them how to proceed.
5. To make things simple: Check the electrical connector at the transmission to be certain it has a tight solid connection that isn't leaking. If that has a lot of fluid on it you could replace the o-rings, check the fluid level to be certain it is at the full mark and give it a test ride.

If that fails to correct the problem drop the transmission pan, replace the conductor plate with a new one,and a filter change, refill the transmission and enjoy the ride.

 

Just a couple things to add to ZIP439's great advice.
There is a limp mode reset under the flap just below the D on the shifter.
If you have a lot of seepage at the transmission plug connector, make sure it hasn't wicked all the way up to the TCU.
You can replace the Orings on the plug or a new plug with Orings is under $15.

 

All above is good advice. If you are willing and mechanically inclined, all this work is medium level of difficulty. If not a tranny shop with European experience or a European mechanic. First check fluid level and will need a special tool. Second jack the car up and check the electrical connector. Tranny fluid leaks around the O-rink and can wick all the way the the transmission control unit (TCU).

Look up fluid changes on the site. Lot's of good information here.

 

This is a great write-up with photos on how to service your trans. Plus it gives you a list of what you will need. Don't forget you will need to purchase a trans dip stick if you don't have one already. And the car has to be running when you check the level.
https://www.fcpeuro.com/blog/mercede...-transmissions

 

Thank you so much for your advice! I will definitely pass this on to the mechanic who is working on the car!

 

The problem was diagnosed as a faulty Speed Sensor and Hydraulic Control Unit/valve body. They are having problems ordering the Hydraulic Control Unit...hard to find as they aren't made anymore. Does their diagnosis make sense to our more astute members? I WAS comfortable with the "O-ring and TCU diagnosis" by our contributing members! My radar is on high alert with this shop's diagnosis! I very well may Jack the car up when I get it back and take a look at the O-rings myself, just to be satisfied with this shop's diagnosis! Wait and see...

 

They do understand it is a 2004 Mercedes SLK320, as for as the mechanics and parts go, correct?

 

This is a link to the conductor plate I spoke of in my first post. They are readily available and not expensive. This link is the entire kit with a new connection plug. It is not a difficult job; conductor plate kit or here condutor plate complete be certain you purchase one that has all new valves and sensors already attached.
The "Speed Sensor and Hydraulic Control Unit/valve body." you mention are both located on the conductor plate and will be brand new as they are part of the new conductor plate.
Best to use only Pentosin or Shell ATF 134 fluid.

 

Just for clarification...my 2005 Crossfire has the 722.6 transmission? The same tranny as the 2004 SLK 320?

 

Yes. I had my valve body rebuilt and with a new conductor plate. There is no need to buy new when a rebuild can be done. A good shop should be able to do it for between 500 and 700 bucks.