Fault code 1818: Diagnosis/troubleshooting

NOTE: Visual inspection: In the next troubleshooting section, please check first that the affected pins on the rear left door control module plug connection are neither damaged nor corroded. The wiring and plugs of the affected components must also be checked for external damage and correct contacts. Repair damaged or corroded pins if possible, otherwise replace affected pins. Repair or replace damaged wires.

NOTE: Sporadic faults: In the event of faults that occur sporadically, the wiring positions that are linked to moving parts on and in the vehicle must be checked for each system. Various statuses that can cause faults must be simulated with the help of the wiring diagram.

NOTE: Battery voltage: A battery voltage of between 11.4 and 14.5 V is required for the following troubleshooting procedure. This must be checked and provided, if necessary. On the vehicle electrical system, the voltage to the fuse (input side) must be guaranteed.

NOTE: The fault is detected if there is ground potential for more than five minutes on plug C, pin 9.

WORK INSTRUCTION CHART

Work instruction			Display OK	If not OK
1	Check rear left door handle	Use the 9588 System Tester II to switch to the menu "Input signals/Rear left door handle". Pull off plug connection to rear left door lock or micro-switch.	Status of rear left door handle changes from closed to open. Go to step 4	Go to step 2
2	Check wiring for short circuit to B+	Switch off ignition. Pull off plug C on rear left door control module. Measure voltage between control module plug C, pin 9 and ground.	< 0.3 V Go to step 3	Repair wiring. → End
3	Check wiring for short circuit to ground	Measure resistance between control module plug C, pin 9 and ground.	∞ Ω Go to step 5	Repair wiring. → End
4	Replace rear left door lock or micro-switch		→ End
5	Replace rear left door control module		→ End