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Compressor relay: Diagnosis/troubleshooting

WARNING: This page is about a different car, the 2006 Porsche Cayenne, 2005 Porsche Cayenne, 2004 Porsche Cayenne, and 2003 Porsche Cayenne. However, it is still accessible from the selected car via links, so may be relevant.
DIAGNOSIS/TROUBLESHOOTING PROCEDURE

Work instruction Display OK If not OK
1 Lower vehicle to low level or loaded level several times if necessary → End Go to Step 2
2 Check fuse Check 1a
  • Switch off ignition.
  • Remove fuse 'F13' (40A) from fuse carrier in back-up fuse box and check for continuity.
 Go to Step 5 Go to Step 3
Check 1b
  • Re-insert intact fuse 'F13' (40A).
  • Measure voltage at output of fuse 'F13' and ground.
 11.4 - 14.5 V
Go to Step 4		 Go to Step 3
3 Replace fuse Fault is no longer present (fuse not faulty).
→ End		 Fault still present (fuse faulty again).
Go to Step 4
4 Inspect the wiring harness from 'F13 fuse output' to compressor relay 'pin A3B (terminal 30)' for pinches and chafing damage. No damage visible.
Go to Step 5		 Repair or replace wiring harness.
→ End
5 Check wiring between compressor relay and level control module for short circuit to B+
  • Switch off ignition.
  • Pull plug A off level control module.
  • Remove compressor relay 'relay socket 3 in relay carrier at left of dashboard'.
  • Switch on ignition.
  • Measure voltage between level control module plug A 'pins 31, 36' and ground.
 < 0.3 V
Go to Step 6		 Repair or replace wiring harness.
→ End
6 Check wiring between compressor relay and level control module for short circuit to ground
  • Switch off ignition.
  • Measure resistance between level control module plug A 'pins 31, 36' and ground.
 ∞ Ω
Go to Step 7		 Repair or replace wiring harness.
→ End
7 Check wiring between compressor relay and level control module for open circuit
  • Measure resistance between level control module plug A 'pins 31, 36' and compressor relay plug A 'pin 3F (terminal 85), pin 3D (terminal 86)'.
 < 5 Ω
Go to Step 8		 Repair or replace wiring harness.
→ End
8 Replace compressor relay → End Go to Step 9
9 Replace level control module → End
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