Client reversed polarity on 2006 MB C280

[Mobitechaz]

https://forums.mercedesclub.org.uk/index.php?threads/c240-key-locked-eis-or-a1-module.63474/

The thread above by OP "Michel" was most relevant to this scenario.
Client reversed polarity accidentally while installing new battery on 06 c280.
Upon initial scan there were numerous codes for CAN faults, most likely due to Battery.

Upon clearing codes, there were only two remaining, one code for central locking mechanism, the other ambient Air Temp (short circuit to positive battery), and 2 codes in the ABS/DSC for Steering Control Module alleging no CAN info from N73 or A1.

Following the OP's advice, I disconnected a fusible link and was able to get the key to turn in the lock cylinder and start vehicle. UPon starting, vehcile showing no alternator voltage. I suspect the ALternator voltage regulator has been compromised, and I'm ordering new VR.

Question is do these codes indicate a Front SAM (drivers or passengers side) issue? I've replaced all fuses and fusible links appear intact. Client reported some smoke when he crossed terminals, but i suspect that smoke was the alternator VR burning up. I didnt appreciate any melted or discolored fusible links.

Seems my situation is exaclty the same as the OP, but that post was 10 years ago, and I am not able to PM him. Thanks for a moment.

Mobitechaz, ASE cert german import

 

[alexanderfoti]

We had a w203 in with reverse polarity damage recently.

Similar codes, needed front sam, rear Sam and the cabke from the alternator to the starter replacing, as it has a 200amp non replaceable fuse in it. Check for continuity to batter plus from alternator plus before you replace the regulator.

 

[ajlsl600]

Expensive.little though this could have been made near impossible

 

[Mobitechaz]

We had a w203 in with reverse polarity damage recently.

Similar codes, needed front sam, rear Sam and the cabke from the alternator to the starter replacing, as it has a 200amp non replaceable fuse in it. Check for continuity to batter plus from alternator plus before you replace the regulator.

Thank you Alexander Foti @ AMF Automotive for responding to my concern. I removed the alternator and yes, confirmed that multiple diodes/wires had been burned completely through, seemed replacing the entire alternator was called for. Replaced alternator new, and now vehicle has proper voltage when operating (14+V).

Several codes however remain as mentioned, and the front headlights and high beams are permanently on, as well as a rear taillights are always on, leading me to consider Front and Rear SAM modules having been compromised. That is consistent with your suggestion above, so again, thank you. I will order Front/Rear SAMs and see if that resolves everything. It seemed the charge cable to the ALT was spared, as the alternator is feeding the battery 14V. Perhaps I got lucky in that regard?

 

[alexanderfoti]

Thank you Alexander Foti @ AMF Automotive for responding to my concern. I removed the alternator and yes, confirmed that multiple diodes/wires had been burned completely through, seemed replacing the entire alternator was called for. Replaced alternator new, and now vehicle has proper voltage when operating (14+V).

Several codes however remain as mentioned, and the front headlights and high beams are permanently on, as well as a rear taillights are always on, leading me to consider Front and Rear SAM modules having been compromised. That is consistent with your suggestion above, so again, thank you. I will order Front/Rear SAMs and see if that resolves everything. It seemed the charge cable to the ALT was spared, as the alternator is feeding the battery 14V. Perhaps I got lucky in that regard?

Yes you lucked out on that one so all good if your car starts and charges now.

For sure both sams will need doing. There may be some door control modules etc as well but you'll know if the door controls or something else stops working.