Reverse not possible

[Ash1999]

Hi all
I have a Mercedes Benz cla 2.1 auto and this morning I got an error on the dash saying reverse not possible. Does anyone no the cause of this and how to resolve.

 

[brandwooddixon]

Sounds like a STAR will be needed to read any codes, but before that check that the battery is in good order.
Low battery voltage can cause no end of issues on start-up.
If you restart the car, after running it for a while (to charge the battery up) and the problem goes away then I'd suspect the battery is at fault.

 

[alexanderfoti]

This is usually caused by a software fault, requiring an update. Either way, that step has to be done first before proceeding with diagnosis of this fault. It will need Xentry or authorised independent workshop with up to date xentry diagnostics equipment to resolve.

 

[Blobcat]

This is usually caused by a software fault, requiring an update. Either way, that step has to be done first before proceeding with diagnosis of this fault. It will need Xentry or authorised independent workshop with up to date xentry diagnostics equipment to resolve.

Software stopping me selecting reverse, please can we stop this madness I'd like to get off...
@ajlsl600

 

[alexanderfoti]

Software stopping me selecting reverse, please can we stop this madness I'd like to get off...
@ajlsl600

Well, its actually an issue with the shift fork actuators. When it detects an issue with number 2, it only gives 2nd, 5th and 7th and you loose 3rd, 4th, 1st and reverse.

It doesn't tell you about the other issues, but does tell you about reverse on the dash.

Most codes say 1. Do software update if its not current then check again. In my experience, this fixes 50% of the cars with no further input, in the others it can be oil level/quality related. If not that then usually actuators/valve body/etc.

But, it has to be diagnosed in that order!

 

[Blobcat]

Well, its actually an issue with the shift fork actuators. When it detects an issue with number 2, it only gives 2nd, 5th and 7th and you loose 3rd, 4th, 1st and reverse.

It doesn't tell you about the other issues, but does tell you about reverse on the dash.

Most codes say 1. Do software update if its not current then check again. In my experience, this fixes 50% of the cars with no further input, in the others it can be oil level/quality related. If not that then usually actuators/valve body/etc.

But, it has to be diagnosed in that order!

So.... if a software update fixes it, then it was a software issue... and mechanically all fine... So the added complexity causes the issues...

 

[alexanderfoti]

So.... if a software update fixes it, then it was a software issue... and mechanically all fine... So the added complexity causes the issues...

Yes exactly. We had one customer say the previous garage instructed them to replace the gearbox or sell the car.....

 

[Ash1999]

So how much is an update at a Mercedes garage cost roughly

 

[LostKiwi]

Software stopping me selecting reverse, please can we stop this madness I'd like to get off...
@ajlsl600

Don't wind up poor Andy!

 

[Antonio1111]

Well, its actually an issue with the shift fork actuators. When it detects an issue with number 2, it only gives 2nd, 5th and 7th and you loose 3rd, 4th, 1st and reverse.

It doesn't tell you about the other issues, but does tell you about reverse on the dash.

Most codes say 1. Do software update if its not current then check again. In my experience, this fixes 50% of the cars with no further input, in the others it can be oil level/quality related. If not that then usually actuators/valve body/etc.

But, it has to be diagnosed in that order!

Hi Alex , I have at the moment one Gla with same issue , they done software update on gearbox and it is still not working .
Did you have problems with forks or ?