Checking the wiring
The diagnostic trouble code indicates that communication between the central electronic module (CEM) and the alternator control module (ACM) (not vehicles with a V8 engine), the left camera module (LCM) (optional extra) and the right camera module (RCM) (optional extra) is inoperative. This could be due to a fault in the signal lead between the control modules or a damaged communication unit in one or all of the control modules.
All vehicles from and including model year 2005 are equipped with a signal cable to the Left Camera Module (LCM) / Right Camera Module (RCM) even if the vehicle is not equipped with BLIS system. This means that measurements must always be carried out up to the 12-pin connector in the external doors when the diagnostic trouble code (DTC) has been detected on LIN bus 2.
Check the signal lead between the central electronic module (CEM) and the alternator control module (ACM) for an open circuit or shorting to ground.
Take readings between:
- Central electronic module (CEM) #C16 (#16) and alternator control module (ACM) #B1.
For vehicles without the Blind Spot Indication System (BLIS)
Check the signal cable between the Central Electronic Module (CEM) and the 12-pin connector in the outer doors. Check for an open-circuit. Check for a short-circuit to ground.
Check the connector in both doors.
Take readings between:
- Central Electronic Module (CEM) D24 (#24) and the 12 pin connector in the external doors terminal #12.
For vehicles equipped with the Blind Spot Indication System (BLIS)
Check the signal lead between the central electronic module (CEM) and the left camera module (LCM) for an open circuit or shorting to ground.
Take readings between:
- Central electronic module (CEM) #D24 (#24) and left camera module (LCM) #5.
Check the signal lead between the central electronic module (CEM) and the right camera module (RCM) for an open circuit or shorting to ground.
Take readings between:
- Central electronic module (CEM) #D24 (#24) and right camera module (RCM) #5.
Also check intermediate connectors.
Remedy as necessary.
Other information
- See Connecting the breakout box
- See Signal specification
- See Location of components
- Replace the generator (GEN) for gasoline engines, see Generator (GEN), replacing
- Change the left camera module (LCM)/right camera module (RCM), see Door mirror, replacing
- See Contents
Was a fault detected?
- YES
OKAY: Troubleshooting has been completed.
- NO
Refer to Checking the component