Fault code 2038: Diagnosis/troubleshooting

NOTE: Visual inspection: In the next troubleshooting section, please check first that the affected 'pins' of the transfer box control unit plug connection and the 'pins' of the plug connections on the servo motor are neither damaged nor corroded. Remove any soiling or corrosion/oxidation. Replace damaged parts/wires.

NOTE: Control unit replacement: Before replacing the 'transfer box control unit', the ground connections, power supply and plug connections on the control unit must be checked as OK. Please observe the coding of the control unit. After the test drive, read out the fault memory again with the Porsche System Tester II No. 9588. Additional causes of faults that could damage the 'transfer box control unit' should be detected and remedied.

DIAGNOSIS TROUBLESHOOTING PROCEDURE

Work instruction			Display OK	If not OK
1	Check voltage supply of potentiometer '1' and potentiometer '2':	Ignition off Pull sensor plug 'B' off servo motor Ignition on Measure voltage at sensor plug 'B' on the wiring harness side between: 'pin B4 and pin B3', 'pin B10 and pin B9' and 'pin B6 and ground'.	approx. 5 V Go to Step 2, measurement '2a'	Measured voltage > 5 V Go to Step 2, measurement '2b' Measured voltage < 5 V Go to Step 3
2	Check short circuit to B+:	Measurement '2a': Ignition off Pull plug 'A' off servo motor Measure resistance at servo motor plugs 'A and B' between: 'pin B10 and pin A1, A2, A3, A4', 'pin B4 and pin A1, A2, A3, A4' and 'pin B6 and pin A1, A2, A3, A4'.	∞ Ω Measurement '2b'	Short circuit between servo motor leads. Go to Step 4
		Measurement '2b': Ignition off Pull plug 'A' off servo motor Pull plug off transfer box control unit Ignition on Measure voltage between 'pins 1, 18, 29' of transfer box control unit plug and ground.	< 0.3 V Measurement '2c'	Repair wiring harness to servo motor. → End
		Measurement '2c': Ignition off Measure resistance at transfer box control unit plug between 'pin 1 and pin 15, 16, 21, 36', 'pin 18 and pin 15, 16, 21, 36' and 'pin 29 and pin 15, 16, 21, 36'.	∞ Ω Go to Step 5	Repair wiring harness to servo motor. → End
3	Check short circuit to ground:	Measurement '3a': Ignition off Measure resistance between 'pins 1, 18, 29' of transfer box control unit plug and ground.	∞ Ω Go to Step 5	Measurement '3b'
3	Check short circuit to ground:	Measurement '3b': On servo motor, pull off sensor plug 'B' and servo motor plug 'A' Measure resistance between 'pins 1, 18, 29' of transfer box control unit plug and ground.	∞ Ω Go to Step 4	Repair wiring harness to servo motor. → End
4	Replace transfer box servo motor		→ End
5	Replace transfer box control unit		See note on replacing control units! → End