The Dreaded 722.6 Auto Box Problem

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Donie

New Member
Joined
Aug 17, 2017
Messages
4
Car
W107 300SL
Hello All,

I know from the search facility that there was a thread started by Triplespeed in October 2016 regarding his ML270's auto box going into second on kick-down and not changing up, even with triptonic.

That thread never reached a solution so I've started this one in the hope of a definitive answer.

I have exactly the same problem.....kicks down into second and will rev on to the moon (so not Limp Home Mode) but will not change up, and when coming to a complete stop will emit a squealing sound similar to brake pad squeal.

I know it's most likely the electroplate, but wondering if anyone with experience can relate their story, and if replacing the electroplate alone totally cures the problem by itself.

Here are the error codes produced :-

P220A Y3/6N2-Y3/6N3 Speed Compar Implausible
P2502 Gear implausible or transmission slipping
P2600 Circuit 87 voltage too low
P2500 Transmission has impermiss transmission ratio

I'm hoping that someone who has been through this can take a few moments to help me.

Thanks in advance.
 
When did it last have an ATF/Filter change?

P220A Y3/6N2-Y3/6N3 Speed Compar Implausible = Electroplate

Not a too expensive repair
 
You should check first supply voltage at terminal 87.Low voltage in these cars cause to much troubles.
 
markmifsud,

No way way of knowing when the ATF/Filter change since I'm only in the process of acquiring the ML270.

Hopefully a replacement electroplate, fluid and filter will leave her happy?

4life211

Where do I find terminal 87 to check the voltage?
What is the cause of low voltage on this terminal?


My thanks to you both for your input.
 
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