CL500 Intermittantly Sticks In Low Gear

[OrsonCarte]

2001 CL500 63,000 miles 722.6 5-sp transmission.

Your expert advice appreciated.

My CL500 occasionally sticks in lowest (2nd?) gear.

I know when it's about to happen because the selected gear displayed on the dashboard display (next to the time) displays 'D' no matter which position the gear selector is in. The S/W button display is also inoperative.

Turning the ignition off and back on again solves the problem....for a while.

On the last occasion it occurred, I immediately parked the car and obtained the following diagnostics from the iCarsoft MBII scanner:

P1856 - shift lever position identification failure
P240C - the selector lever position sent from control unit N15/5 (electronic selector lever module control module) via the CAN bus is implausible
P2600 - circuit 87 voltage too low
Datastream - selected gear by means of selector lever (CAN) implausible

After turning the ignition off and back on, checking that the gear selector display was back to normal and rerunning the diagnostics, none of the above warnings were generated and I could continue driving as normal.

I have confirmed that the battery is good with a multimeter. The transmission fluid levels are absolutely spot on and the fluid is a brown-gold colour with no trace of burning. I have also confirmed that the kick-down switch is not sticking.

Besides this occasional glitch, the car runs like a dream. The problem appears to be sensor-related and the car has got previous in this department having displayed several erroneous error messages in the past.

I would be very interested to know if anybody has seen an identical set of symptoms and has identified the specific issue. I am reluctant to pull out the electronic gear selector mechanism when I don't really know what I am attempting to fix. Although I am still mobile, it is a little nerve-wracking not knowing when it is going to happen next.

Thanks in advance.

 

[Doodle]

The last time I recall mention of shift position failure/implausible selection, it was knackered engine/gearbox mounts allowing things to move around and push the selector out of range. One of Olly's customers with a CLK, I believe.

 

[OrsonCarte]

Many thanks for your input. I have taken a look at the mounts and they look OK to me. Also, there is no discernible vibration nor any unusual noise from the engine compartment.

 

[Doodle]

I wouldn't expect there to be. Even with engine mounts that are utterly destroyed like the below, there was nothing outwardly amiss.

 

[renault12ts]

I wouldn't expect there to be. Even with engine mounts that are utterly destroyed like the below, there was nothing outwardly amiss.

You think...start at 1:42

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[Doodle]

I know...the mounts pictured came out of my SL, it was nowhere near the symptoms shown in the video.

It does make you wonder just how bad those must have been.

 

[renault12ts]

I know...the mounts pictured came out of my SL, it was nowhere near the symptoms shown in the video.

It does make you wonder just how bad those must have been.

Utterly destroyed?

 

[Doodle]

Clearly, there must be a new level of totally borked that I had not yet encountered.

 

[grober]

For heavily electronic dependent cars like your Mercedes its imperative that all the control electronics get a stable power supply. First check would be battery[ age] and alternator [ regulator]- are they up to the mark. Next might be the K40 relay that supplies voltage to many drivetrain systems. Sounds as if your transmission is going into safe mode because its electronics are giving conflicting messages. Its perhaps a communication problem between the selector mechanism and the gearbox so it could be at the gear selector end or at the gearbox end. You car will have the 722.6 gearbox which can have problems with the electrical connection socket and/or internal conductor plate [ common problems on older transmissions].

some 722.6 lowdown
http://shop.ukrtrans.biz/wp-content/uploads/catalogs/722.6.pdf

 

[OrsonCarte]

Many thanks for the really useful PDF; serious bedtime reading. I'm a little disappointed to be driving a Chrysler though.

 

[OrsonCarte]

Yes, almost certainly a communication problem because once the car is on the open road it goes for miles without any issues whatsoever. The problem only occurs from standstill and then only occasionally.