E320 CDI AUTO 2001 not changing gears, can anyone help please?

[tmirza]

Hi there, I am a new member and I don't know if you can help me but my merc won't change gears, it stays on 1st gear all the time, i don't think it can be the gearbox itself as it is not slipping and I am not hearing any rattling or broken bits coming from the gearbox so I was wondering if it could be the ECU or does the car have any other gearbox sensors which tells it to change gears?

At first when it wouldn't change gears if I switched the car off and then on again it would work fine but now it just won't change gears at all and even the tiptronic manual gear change won't work either.

Could it be the ECU or any sensors?

Would be very grateful for any advise.

 

[Xtractorfan]

oil contamination in the ecu will cause this, simple to fix, there are numerous threads on here about that problem.
also rad coolant leaking into the autobox again numerous threads on here
The ecu u can check yourself and basically repair/dry out.
Check on here for location of ur ecu and disconnet battery before removing or disconnecting it, and it will need resetting on a STAR machine
if u need more help shout

 

[Tontastic]

To state the obvious ...

Hi there, I am a new member and I don't know if you can help me but my merc won't change gears, it stays on 1st gear all the time, i don't think it can be the gearbox itself as it is not slipping and I am not hearing any rattling or broken bits coming from the gearbox so I was wondering if it could be the ECU or does the car have any other gearbox sensors which tells it to change gears?

At first when it wouldn't change gears if I switched the car off and then on again it would work fine but now it just won't change gears at all and even the tiptronic manual gear change won't work either.

Could it be the ECU or any sensors?

Would be very grateful for any advise.

It sounds like your car is in "limp home" mode, which sometimes clears itself on ignition and sometimes will only clear via a STAR computer. Search the forum, there will be a much better explanation of this mode.

 

[television]

This could be one of a few things like the loss of a speed signal , MAF down and in the limp home mode, or the conductor plate in the box

 

[Xtractorfan]

Malcolm just wondered and i am picking ur brains here would the MAF cause the gearbox to go into limp mode, or even engine limp mode cause the gearbox to vote in sympathy.. these things are good to know
thanks

 

[Dom320]

Hi there, I am a new member and I don't know if you can help me but my merc won't change gears, it stays on 1st gear all the time, i don't think it can be the gearbox itself as it is not slipping and I am not hearing any rattling or broken bits coming from the gearbox so I was wondering if it could be the ECU or does the car have any other gearbox sensors which tells it to change gears?

At first when it wouldn't change gears if I switched the car off and then on again it would work fine but now it just won't change gears at all and even the tiptronic manual gear change won't work either.

Could it be the ECU or any sensors?

Would be very grateful for any advise.

Mine displayed the exact symptoms you describe when my battery was on the way out. I changed the battery, and everything was fine again.

Would be worth checking.

Dom.

 

[television]

As Dom posted, do make sure that you have 12.5 volts before the start.

The MAF can put the engine in the limp home mode as the output will be down and the gearbox does not know what to do.

Unplugging the MAF will often restore the engine to full power, though the car may run rough.

 

[maddog]

Malcolm just wondered and i am picking ur brains here would the MAF cause the gearbox to go into limp mode, or even engine limp mode cause the gearbox to vote in sympathy.. these things are good to know
thanks

I dont know whether the maf could make the gearbox go into limp mode but when i had a maf failure on my car the gearbox was unaffected just the engine.

 

[OlafMaxwell]

I dont know whether the maf could make the gearbox go into limp mode but when i had a maf failure on my car the gearbox was unaffected just the engine.

I must add my comment to Maddog, I have had both problems.

The MAF goes and its like the turbo is off [which it is] and you lack power but have all the gears. Mine went some time back, I think about 85k.

The transmission problem...it stays in 2nd, not first, max speed is 40mph. To get from drive to reverse you have to turn off the engine first and then restart it. When this happened I had to get the servo changed. Mine went at 105k, and there does seem to be some coincidence with the battery failure which I also suffered but afterwards. If your battery is of unknown vintage or condition its worth a change. I got 7 years out of the original battery.

 

[tmirza]

Hi Guys,
Thanks for all your help and suggestions.
It does sound to me that the problem is more electrical as the car is in limp Home mode. The car will go about 30mph at maximum revs before it reaches the red but I'm not sure if it is stuck in 1st or 2nd gear.
Alao Going into reverse or from reverse to drive there is no need to switch the car off but it has started to make a noticeable jerk when selecting the gears. The tiptronic doesn't work either which I think it is a safety feature to prevent any further damage from occuring.
I have taken the car to an independant merc speacialist but no codes are showing on their computer.

So any more help and suggestions will be so much appreciated.

Thanks once again.

Tony

 

[Parrot of Doom]

Have you or anyone you know spilt any drinks into the gear selector?

Will the car start from 2nd gear if you select 'W' mode? I would be very surprised if you could reach 30mph in 1st gear.

 

[AnthUK]

Had similar problem with mine and dealer diagnosed contamination of some control unit on gearbox. They cleaned unit and moved it. Did not trouble me again.

 

[brad190]

Hi Timirza,
I am having the same probs with my gearbox & wondered if you got your sorted please?