[Techmann]

Hello, I have a 2008 Smart Passion with 118,000 miles and recently I've been having shifting issues. It doesn't matter whether I am using manual or automatic shifting and recently what has been happening is I will be driving in 3rd or 4th gear (going around 30-40MPH) on normal level terrain and not straining the engine at all and then all of a sudden the car will downshift into 1st gear without even going into 2nd gear first. Of course when this happens, the engine revs really high and the car starts slowing down abruptly due to the downshifting effect. Once this happens, the car stays stuck in 1st gear and I can no longer shift out of 1st gear even if I switch to manual mode. The only way I have found to fix this is to turn off the car and restart it...sometimes it fixes it but sometimes the problem persists. I'm worried to drive it on the freeway because if I'm doing 65 in 5th gear and it decides to do this, the engine will probably blow, or worse, skid and cause an accident. Has anybody seen this problem before or know what things I should start checking? Thank you.

 

[jwight]

Have you scanned the car for OBD codes?

 

[smark]

^^^^^^ ditto above comment. Transmission software is corrupted. Might have to take it to a MB dealership.

 

[twcom]

Please keep us updated on this issue and hopefully ultimate resolve.

My well wishes out to you.

 

[Techmann]

I plugged in my OBD scan tool and it showed no stored or pending error codes. I will drive it around some more and hopefully when it fails next time it will produce an error code.

 

[gtdump]

I plugged in my OBD scan tool and it showed no stored or pending error codes. I will drive it around some more and hopefully when it fails next time it will produce an error code.

You will need a tool which can scan CANbus, many basic OBD readers don't.

 

[Techmann]

Yes, the tool I used can scan CANbus. I did some more research and found this post Transmission Problem/Car switching into Neutral. The symptoms are the same as what I'm experiencing except my car goes to 1st instead of neutral. The problem turned out to be a bad transmission control unit (TCU). When I get a chance, I'm going to check all the electrical connections at the TCU to make sure nothing is corroded and also the connection at the Transmission RPM sensor and will report back.

 

[Rich Carson]

Hello, I have a 2008 Smart Passion with 118,000 miles and recently I've been having shifting issues. It doesn't matter whether I am using manual or automatic shifting and recently what has been happening is I will be driving in 3rd or 4th gear (going around 30-40MPH) on normal level terrain and not straining the engine at all and then all of a sudden the car will downshift into 1st gear without even going into 2nd gear first. Of course when this happens, the engine revs really high and the car starts slowing down abruptly due to the downshifting effect. Once this happens, the car stays stuck in 1st gear and I can no longer shift out of 1st gear even if I switch to manual mode. The only way I have found to fix this is to turn off the car and restart it...sometimes it fixes it but sometimes the problem persists. I'm worried to drive it on the freeway because if I'm doing 65 in 5th gear and it decides to do this, the engine will probably blow, or worse, skid and cause an accident. Has anybody seen this problem before or know what things I should start checking? Thank you.

Try watching this video:

Greasing the parts worked for me.