Diagnosis/troubleshooting PSM 5.3

DIAGNOSIS/TROUBLESHOOTING PSM 5.3 (FAULT CODE 4266)

Work instruction			Display OK	If not OK
1	Check supply voltage of the relay for the return pump for open circuit	Switch off ignition Pull relay for return pump out of the socket Switch on ignition Measure voltage between relay for return pump of socket pin 4 and ground	>11 V Step 2	Open circuit in electric circuit between relay for return pump socket pin 4 and PSM control module pin 2 ->End
2	Check relay for return pump for short circuit to ground	Switch off ignition Measure resistance between relay for return pump of socket pin 6 and ground	Step 3	Short circuit to ground between relay for return pump socket pin 6 and PSM control module pin 7 ->End
3	Check relay for return pump for short circuit to B+/ open circuit in electric circuit	Switch on ignition Measure voltage between relay for return pump socket pin 4 and relay for return pump socket pin 6	>11 V Step 4	Short circuit to B+/open circuit between relay for return pump socket pin 6 and PSM control module pin 7 ->End
4	Check relay for return pump for short circuit to ground/ open circuit	Measure voltage between relay for return pump of socket pin 2 and ground	>11 V Step 5	Short circuit to ground / open circuit between fuse F1 and relay for return pump socket pin 2 ->End
5	Check ground supply for relay of return pump for open circuit	Switch off ignition Pull plug off the PSM hydraulic unit Measure resistance between plug on PSM hydraulic unit pin 13 and ground	< 5 Step 6	Open circuit between PSM hydraulic unit pin 13 and ground point 2 ->End
6	Check return pump	Connect plug of the PSM hydraulic unit Connect electrically protected wiring harness jumper to the relay for the return pump socket pin 2 and the relay for the return pump socket pin 8 (do not let return pump operate for longer than 5 sees!)	Return pump is operating Step 7	Open circuit between relay for return pump socket pin 8 and PSM hydraulic unit pin 14 ->End
7	Check voltage supply for relay of return pump for open circuit	Pull plug off the PSM control module Measure resistance between PSM control module pin 20 and relay for return pump socket pin 8	< 5 Step 8	Open circuit between relay for return pump socket pin 8 and PSM controle module pin 20 ->End
6	Relay for return pump faulty		->End