Automatic transmission – gone into limp mode

[Dave Chaucer]

Hello,

I have only driven about 600 miles since I had the electrics kit (part No. A1402701161) replaced on my 320cdi auto (2001).

The gears have become erratic and unfortunately the car has gone into limp mode. I took the vehicle back to the independent Mercedes garage (who carried out transmission oil change/filter and had replaced the electrics kit).

The garage then hooked it up to the scanner and codes revealed the problem was down to faulty speed sensors. The garage cleared the codes and the car is running fine now. They want the car back next week to address the problem.

My understanding is that a new electrics kit contains the speed sensors and clearing the codes has just masked the issues.

I have a couple of questions, firstly are there any other speed sensors other than the ones in the electrics kit?

Also is it likely that the garage has not replaced the electrics kit or if they have it was not a new one?

Thanks in advance for your help.

Dave

 

[rpe2]

A failing battery will give similar symptoms to a failed electroplate.

 

[Dave Chaucer]

Thanks Richard, hopefully the battery is okay, it's only about four weeks old.

 

[MERCSPORT]

You have ABS Speed Sensors on each of your four wheels, which can affect a number of things, the trouble is finding which one is causing the fault, from what I know.

As for the electronics kit, it could have possibly been faulty, or fitted incorrectly etc. whatever the problem is, as long as the garage has agreed to fix it, and it is sorted.

Others who have more experience than me, will come along.

 

[Dave Chaucer]

Thanks mercsports

 

[Steve@Avantgarde]

The electrics kit only contain the speed sensors, but could you have a solenoid issue on electrohydraulic plate? A speed plate failure can often mask this.

A failing battery would only chuck it into limp mode, nothing more, so that isnt your issue and as the op has not mentioned anything about an ABS warning light I would assume it is not a wheel speed sensor causing this fault.

 

[Dave Chaucer]

Thanks Steve, Is the electrohydraulic plate the same thing as the electrics kit, conductor plate or electric plate?

Are these (green arrows pic attached) where the solenoids would sit?

 

[television]

The speed plate as its called is bolted to the valve block

 

[Steve@Avantgarde]

The electrohydraulic plate is what the electrics kit attaches to. There are also seperate valves which then are fitted to the electrics kit. Some of the valves arent available seperately and are supplied with a new EHCU. Which also has a new electrics kit.

 

[Dave Chaucer]

Thanks Steve, I have found an image (attached) so have a better understanding.

In late January the diagnostic test results showed the following

ETC - Electronic transmission control

13 Component y3/6n3 (speed sensor) is faulty

109 Component y3/6n3 (speed sensor) is sporadically faulty

130 CAN communicate with control unit N15/5 (Electronic selector lever module control unit) is sporadically disturbed.

148 The torque converter lock-up clutch causes a sporadic impermissible closing


ESM - Electronic selector module


P1856-005 Selector lever position has failed



The garage then proceeded to replace the electrics kit (electric plate) etc.

Is it correct that a new electrics kit would contain speed sensors of which y3/6n3 is one?


Is it usual that the speed sensors would have failed so quickly?

 

[Dave Chaucer]

http://www.youtube.com/watch?v=8c7pDR83d_E

That looks easy enough