Fault code 1135: Diagnosis/troubleshooting

NOTE: Visual inspection: In the next troubleshooting section, please check first that the affected pins on the rear convenience system control unit plug connection are neither damaged nor corroded. The wiring and plugs of the affected components must also be checked for external damage and proper contact. 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.

WORK INSTRUCTION CHART

Work instruction			Display OK	If not OK
1	Check fault type using [F8]		'No signal/communication' Go to step 2 'Faulty' Go to step 7
2	Check fuse	Check fuse in left fuse carrier (F34, 5A)	Go to step 3	Replace fuse and remedy the cause, if necessary → End
3	Check power supply (terminal 30)	Switch off ignition Pull plug off passenger compartment sensor Measure voltage between pins 3 and 4 on plug	11.4 to 14.5 V Go to step 4	Repair line → End
4	Check serial port for short circuit to B+	Pull plug B off rear convenience system control unit Measure voltage between pin 1 and ground on control unit plug B	< 0.3 V Go to step 5	Repair line → End
5	Check serial port for short circuit to ground	Measure resistance between pin 1 and ground on control unit plug B	∞ Ω Go to step 6	Repair line → End
6	Check serial port for open circuit	Measure resistance between pin 1 of control unit plug B and pin 5 of passenger compartment sensor plug A	< 5 Ω Go to step 7	Repair line → End
7	Replace passenger compartment sensor		→ End