Well, I've got a DTC on my S500 coupe... doesn't affect driveability at all (wouldn't have found it except testing a new scanner chip). No check engine light, etc.
According to manual, its "Right Adjustable Camshaft Timing Logic Chain"... hard to say that three times real fast!
Anyway, did the basic tests outlined in the manual (all of which have to do with testing the solenoid on the right bank) and can't find anything wrong. Solenoid tests out at 9 ohm (identical to left).
Next step in the "flow chart" is to jump into the wiring, but before I do that, thought I'd check with some of the experts here to see if this is a common issue and what probable causes may be... or, is it uncommon and I'll just have to slug my way through all the tests. I don't like the idea of jumpering main connections at the ECU unless I have to.
Is the mechanical part of the cam adjuster prone to failure... ? or is this almost certainly electrical? which is what the test procedures would suggest.
Thanks.

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KenP

1996 S500 W140 Coupe

Typically logic chain codes mean that all the components check out properly and yet the action desired didn't take place or meet a standard.

The test with a scanner activates the solenoid and the result is the engine runs poorly. The closest thing I have seen to your problem was such codes after head gasket repairs on 104 motors where the chain was off a tooth.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Hi Steve. Thanks for the note.
Sounds like failure of the adjustable cam timing mechanism isn't a common problem... at least if you haven't seen it. :-)
Don't think the valve covers have ever been off this motor, so doubtful it was assembled wrong... and it runs flawlessly.
From what I can read, the test that the ECU does is once per "trip" and it confirms that the intake manifold pressure changes by more than a fixed amount within a second after the cams are ordered to advance. This apparently happens around 3K rpm or so depending on load/etc. If this happens twice, the code is set, but no check engine light is registered.
Guess I'll have to dig deeper and do the harness tests that the manual calls for. Meanwhile I've cleared the code; we'll see if it comes back.
As you said, it also calls for the solenoids to be activated one at a time to see if the idle turns rough... i.e. the cam adjusters are working.
Thanks again.

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KenP

1996 S500 W140 Coupe