ML 270 auto box limp mode

[kebo57]

Hi
I have had limp mode occurring progressively over the last month up to about three our four limp modes a day
But now its stuck in limp mode I would say stuck in second gear 30 mph = 2500 rpm

When I select reverse I get a clunk & slight lunge back wards
Then when I select neutral its slightly smoother no lunge
Then when I select drive I get the same clunk and a slight lunge far wards
Same as above when I go back to Park

I've had a few clunky changes over that time usually goes into limp after the clunky change

Also when you brake with out stopping and then accelerate it sort of looses its self and goes in to limp mode.

I've been careful with the box over this time

I've dropped the oil and pan today and its clean not bits, oil still has a reddish color it lookers better than the other times I have inspected it, oil level is OK

I've disconnected the battery, changed the MAF, still stuck in second gear
I'm going to Frank Masseys to morrow to get the codes cleared hope this will help

AS usual any help would be gratefully appreciated

Kevin

 

[television]

Sorry to hear this Kev.

One fault known is loose connector on the ECU and the other the speed sensor defective (common fault) gives codes
012,013,108 and 109 stored in memory.

I have met frank,,a super guy

 

[kebo57]

Sorry to hear this Kev.

One fault known is loose connector on the ECU and the other the speed sensor defective (common fault) gives codes
012,013,108 and 109 stored in memory.

I have met frank,,a super guy

Hi Malc and thanks for this
Where would I find the connector on the ECU
& is the speed sensor in the box our external
I'll take them code with me tomorrow
I was a bit down with this but feel better you are listening

Kevin

 

[television]

I have lost that page now, as to where the ECU is.

As it is intermittent it might be the loose connector

The speed sensor is in the box and not that expensive and easy to change, I can give you a how to paper if need be

Good luck tomorrow

 

[kebo57]

Hi this is the update
There is no response from the auto box control unit so frank couldn't tell me any codes clear/re-set anything. they cant communicate to where the speed sensor is to check it
So they suggested maybe oil in the loom so I should locate the unit and check all the connections my self to keep the price down, they had a quick wiz round but couldn't locate the unit, and then get back to them.

Just wondering now if when the earth lead (engine mount to chassis) broke of that it tried to earth through the auto box unit when I tried to start the motor.

Kevin

PS going to try and locate the unit

 

[Cole@MBS]

Hi this is the update
There is no response from the auto box control unit so frank couldn't tell me any codes clear/re-set anything. they cant communicate to where the speed sensor is to check it
So they suggested maybe oil in the loom so I should locate the unit and check all the connections my self to keep the price down, they had a quick wiz round but couldn't locate the unit, and then get back to them.

Just wondering now if when the earth lead (engine mount to chassis) broke of that it tried to earth through the auto box unit when I tried to start the motor.

Kevin

PS going to try and locate the unit

Its here Kev

http://www.detali.ru/cat/oem_mb2.as...GM=716.644&CT=F&cat=06H&SID=54&SGR=080&SGN=06

 

[kebo57]

Thanks sam
I looked in the drivers side foot well panel last night but could only see relays & fuses
Frank recond under the dash both side could be a good place to start

Kevin
OK got it but it looks OK, it was up behind the diagnostic socket

 

[television]

I will find it for you

 

[television]

Kevin, its under the kick panel drivers side

Activate your Email in you user CP and I can send you the paper,, poor connections like I said could be the cause then and STAR not making contact

 

[psmart]

Hi Kevin,

Zour PM box is full, tried to respond to your PM this morning but was unable.

If its not the ECU, then the Valve Body was to be my suggestion, as like you, I got the thud and then safe mode (always locked in 2nd at slow speeds, 4th at high speeds).

 

[kebo57]

Kevin, its under the kick panel drivers side

Activate your Email in you user CP and I can send you the paper,, poor connections like I said could be the cause then and STAR not making contact

I found it but edited three postes back with pics

Kevin

 

[kebo57]

Hi sorry phil iv'e dumped 12 messages

 

[television]

Yes you posted the same time as me, was the connector making good contact, the end 2 ones are the CAN communicating wires

 

[kebo57]

Hi Kevin,

Zour PM box is full, tried to respond to your PM this morning but was unable.

If its not the ECU, then the Valve Body was to be my suggestion, as like you, I got the thud and then safe mode (always locked in 2nd at slow speeds, 4th at high speeds).

Hi phil was you able to retreive the codes though

Kevin

 

[kebo57]

Yes you posted the same time as me, was the connector making good contact, the end 2 ones are the CAN communicating wires

Iv'e got 5 plugs to disconect, then the small black box center pic bottom right with the multi plug (same style as computer extra memory commection)
all conections look clean and good, I'm going to reassemble & try it again

Thanks all

 

[psmart]

Yep, I was able to read the codes, but I dont have to hand the exact number, but were firstly indicating a RPM 3 Sensor malfunction, then a total gearbox failure (this was when the box jumped out of gear and wouldnt select a gear until the vehicle speed got down to about 20mph).

If some earth fault has caused a power surge through the ECU, anything could have happened and quite often electronic parts dont look damaged (ie. the IC's). Consider this as a last possibility as they are expensive. To know if the unit was damaged, you would need a test rig (perhaps Fred Massey?). Did you check the connector on the box to see if it was leaking mentioned by Television below?

 

[television]

Yes the fault codes I put up were for the speed sensor, and failing to communicate with the ECU

There are only 2 plugs on the ECU

 

[kebo57]

Yes the fault codes I put up were for the speed sensor, and failing to communicate with the ECU

There are only 2 plugs on the ECU

Maybe I got the wrong item part no is below
http://www.mercedes-benz-parts.co.u...ls&flypage=shop.flypage&option=com_virtuemart
2 plugs on the ECU would this be back of the fuse box under the bonnet


Kevin

 

[television]

I have printed off a copy for you of the WIS but cant send it as no Email address and my PM box is full

 

[television]

Kev I have cleared a PM so one space to send your Email