URGENT !! ML270 Auto Box No Neutral / Park signal

rjevon

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Afternoon,

The ongoing saga of my ML270...

I have Starting issues where the Starter solonoid will not get an earth switch signal after the car has been driven, thus when I turn off the engine it will not start again until cooled down.

Had an auto electrician out today who can see with his STAR equipment, and a bunch of other stuff, that no earth switch signal is detected when the gearbox is in Park or Neutral... All other gears are recognised by STAR but not Park and Neutral..

This is stopping the K8 realy from getting an earth switch to engage and start the car.

Although applying a switched earth with a little device he had to the K8 relay brings the car to life..

I have had no limp mode on the gearbox for ages, although WMD in Perry Barr did fine the following and cleared them (which I thought was causing limp mode which went away after they cleared the codes)..

They said that a couple of codes stored pointed to the Electro Plate that needs replacing, these are :-

P2220 - Component Y3/6s1 (Starter lockout contact) or component Y3/6b1 (Transmission oil temperature sensor) is faulty or both.

P2222 - The signal of component Y3/6b1 (Transmission oil temperature sensor) and (or) Y3/6s1 (Starter lockout contact) is implausible.


I assume from the descriptions that these would cause the lack of Earthed Switch Signal to enable the K8 relay to switch.. ? As I assume the 'Starter Lockout contact' is the lack of signal to enable starting ?

HELP
Richard
 

Alex Crow

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Gears read out on Star will be from selector module and transmission ECU - in other words there are no gear position sensors in the gearbox as such.


Yes, the fault codes in relation to the trans oil temp sensor/starter lock out do point towards a fault with this switch or connections to it.

A curious design, the starter lock out/oil temp circuit.
Both the lock out switch and temp sensor share the same wiring, and are in series.
The lock out switch is open circuit when in park and neutral.
Hence oil temp can only be read out in gear!
 
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rjevon

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Gears read out on Star will be from selector module and transmission ECU - in other words there are no gear position sensors in the gearbox as such.


Yes, the fault codes in relation to the trans oil temp sensor/starter lock out do point towards a fault with this switch or connections to it.

A curious design, the starter lock out/oil temp circuit.
Both the lock out switch and temp sensor share the same wiring, and are in series.
The lock out switch is open circuit when in park and neutral.
Hence oil temp can only be read out in gear!

So Electroplate replacement is the most possible solution then ?

Its not intermittent, it can be replicated every single time after a run.

Richard
Richard
 

Alex Crow

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If symptoms are repeatable, do pin out tests at the transmission ECU or electroplate first.

Trans ECU is fitted above the parking brake foot pedal (just follow oil stain upwards).
You are looking for a variable resistance when in R or D, and open circuit in P or N.
At ECU, pins 33 Blue and 34 Green
At electroplate pins 4 and 12

Unusual for an electroplate to give an issue like this, although I have seen it before when a transmission specialist had not fitted the 'plate properly - they should have known better!
 

Steve@Avantgarde

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I have been mulling over this fault as it sounded familiar. About a year ago I had an ML which was going into limp mode intermitantly with speed sensor issues and Im sure it had a oil temperature fault code too.

I fitted an electro plate which didnt cure the problem, despite actual values in star giving all the usual indications it needed one. The issue I had was an issue I have seen about 3 times since, all on ML's. The wiring loom going to the electro plate is angled differently to other models and rests on theedge of the heatcover for the pilot bush. The heatcover had cut through to the wiring and it was arcing out on the cover storing fault codes for speed sensors and other things. I repaired the wiring loom and it has been perfect since.

I would check the loom going to the pilot bush to see if you havent got this issue first.

Just a thought.
 
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rjevon

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I have been mulling over this fault as it sounded familiar. About a year ago I had an ML which was going into limp mode intermitantly with speed sensor issues and Im sure it had a oil temperature fault code too.

I fitted an electro plate which didnt cure the problem, despite actual values in star giving all the usual indications it needed one. The issue I had was an issue I have seen about 3 times since, all on ML's. The wiring loom going to the electro plate is angled differently to other models and rests on theedge of the heatcover for the pilot bush. The heatcover had cut through to the wiring and it was arcing out on the cover storing fault codes for speed sensors and other things. I repaired the wiring loom and it has been perfect since.

I would check the loom going to the pilot bush to see if you havent got this issue first.

Just a thought.

Cheers,

Will check this later tonight or tomorrow if I can get access to a ramp.

Much appreciated.

Richard
 

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