mckcol

Hi All, problems with my R230 SL500 that I have owned for 3 or 4 years.

Roof was down, car left for an hour. On driving off, came up on dashboard with red battery on left display and visit workshop on right.
Roof refused to go up, various functions not working, fuel guage reading zero, rear indicators not working (front ok), windows not doing their auto retract when opening door.
I disconnected both batteries for 5 mins, no change.
Drove for 30 mins and stopped at services. After 15 min stop, all had reset and was fine. So put roof up to continue our trip.
Fault has now returned.
Obviously can't be a fuse.
Battery voltages seem ok, have repeated diagnostics with a charger connected (13.5V on battery)
Checked on diagnostics, all seem to be related to the rear SAM module. I have checked all fuses, and connections to this module.
Faults:
B1076 Control unit N10/8 (Rear SAM control module) is not transmitting data on the CAN bus.
B1021 Control unit A37 (PSE control module) is not transmitting data on the CAN bus
B1091 Control unit N52 (RVC Control module) is not transmitting data on the CAN bus
Faults are current and can't be cleared.
I am thinking (hoping!) that it could be simply a wire break on the CAN bus to the rear SAM module.

Can anyone point me in the direction of where this CAN bus runs, where the ends are, so I can try some continuity checks?
Sadly car currently unuseable
Thanks all!

MikeJ65

There is a CAN-B hub in the right rear cubby in the vicinity of the rear fuses. You probably have some corrosion that needs to be cleaned up.

mckcol

Thanks Mike - how do I identify this module?

MikeJ65

It is a long black plastic socket with 8-10 brown wire pairs plugged into it.

g0rsq

Quite fiddly to remove plugs

Squeeze to tabs at each end, and base slides sideways.

Once base removed then need to insert very small screwdriver to release each plug.

Fitting position doesn't matter, but better to keep original locations

aolexy

Did you find out what was the problem? I am having the same type of issue and looking for solution.

Thanks

mckcol

Hi, yes found fault. The car had had an automated roof module fitted that had failed.

This was fitted under the carpets on the driver side (RHD) - I removed the module (which is in series with the canbus) and connected the canbus back together as factory fitted.

All fine now - I don't have the automated roof functions now, which is a pain.

hhagens

What was the automated module ???

mckcol

It was an aftermarket fitted module that automated the roof function. One press to open or close roof (didn’t have to hold button), allowed roof function when vehicle was moving (up to 20 mph) and allowed remote opening and closing using keyfob.

MR.AMG.

Hi would you what guage wiring is used for the can bus? Let me know please