#PIP4862A: Service Rear Axle Message Displayed DTC C0407 Sym64 - (Sep 21, 2011)

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Wilfrid Cunningham
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1 Page 1 of 5 Document ID: #PIP4862A: Service Rear Axle Message Displayed DTC C0407 Sym64 - (Sep 21, 2011) Subject: Service Rear Axle Message Displayed DTC C0407 Sym64 Models: Buick Lacrosse Cadillac SRX Equipped With All Wheel Drive (AWD) This PI was superseded to update model and model years. Please discard PIP4862. The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI. Condition/Concern: Some customers may comment that the service rear axle message is displayed on the DIC. During diagnosis technicians may find a C0407 sym64 stored in the Rear Differential Clutch Control Module (CCM). Note: GDS diagnostics must be used to confirm what DTC is set in the CCM. Recommendation/Instructions: The C code is set when the oil is low in the Differential Clutch. There are several conditions that can cause the Differential Clutch to be low on fluid: 1. Improper filling of the Differential Clutch during the Differential Clutch filter/gasket service or pump replacement. 2. Differential Clutch oil leaking into the Rear Differential through the Limited Slip Differential Clutch. 3. External leakages on the Differential Clutch. Replacing the control module or module kit WILL NOT correct this condition. Removing the control module and valve will purge some of the air from the pump motor cavity, which will give a false condition that a new control module was the correct repair. Follow the procedures below to help diagnose the root cause of the C code. A) If the vehicle has had a previous filter or pump replacement and the C is set follow the instructions below; if not go to Procedure B. The Differential Clutch is properly filled when the fluid level is level with the bottom of the differential clutch cover plug and the pump cavity (4) is full. The pump cavity is full when the pump motor current is between A while the engine is running and the pump motor is running. The 2011 General Motors. All rights reserved.

2 Page 2 of 5 current cycles from 0 to A as the pump turns off/on. Both conditions MUST be met. If the pump motor current is consistently below 2.5A, then the pump motor cavity (4) is low on fluid. Important: When filling the differential clutch housing after repairs, the fluid must be able to flow over the top of the internal wall of the pump cavity (3 and 4), making it imperative that the fluid is filled through the vent opening (1) with the cover plug (2) installed. The bottom of the cover plug opening (2) and the internal wall (3) are at the same level. If the cover plug (2) is not installed, the fluid will fill the differential clutch oil sump (5) and run out of that opening (2) before it can flow over the wall (3) into the pump cavity (4). Fluid part number U.S. ( Canada) will be needed and can be obtained from GMSPO. If the fluid level is level with the bottom of the differential clutch cover plug (Fig. 3, B) and the pump motor current is below 2.5A then the differential clutch pump cavity is empty. If this is the case the Differential Clutch needs to have fluid added using the following procedure: 1. Clear all DTCs 2. Raise the vehicle and support the vehicle. 3. Remove the vent hose from the fitting. 4. Remove the vent hose fitting from the differential clutch cover. 5. Fill Differential Clutch with 50mL through the vent opening (1) on the cover, ensure that the fill plug (2) is installed prior to adding fluid through the vent fitting. 6. Install the vent hose fitting and tighten the fitting to 14 N m (10 lb ft). 7. Install the vent hose. 8. Remove the supports lower the vehicle. 9. To stabilize the oil level, let the vehicle rest 10 minutes with the ignition off. 10. Start the vehicle and allow running for 5 minutes at idle. 11. In park, cycle throttle from idle to wide open throttle briefly 5 times waiting a minimum of 30 seconds between each WOT cycle, to cycle solenoids to purge air. 12. With engine running, observe the scan tool Rear Differential Clutch Pump Motor Current parameter. If the parameter display is above 2.5A when the pump is on then go to Step 11. If the current is below 2.5A then shut the vehicle off and go back to Step Shut the vehicle off. 14. Raise the vehicle and support the vehicle. 15. Remove the differential clutch cover plug (2) and check the differential clutch fluid level. 16. The differential clutch fluid should be level with the bottom of the differential clutch cover plug hole (2). If the differential clutch is overfilled drain out fluid until it is at the proper level. Add fluid through the vent opening (1) if the differential clutch is low on fluid. 17. Install the differential clutch cover plug (2) and re-tighten to 14 N m (10 lb ft). 18. Lower the vehicle.

Page 3 of 5 19. Drive vehicle 3-5 miles to confirm that DTC does not reset. B) If the vehicle has not had a previous Filter or Pump replacements please follow the following steps. 1. Please check the RDM for conditions a) and b).

3 Page 3 of Drive vehicle 3-5 miles to confirm that DTC does not reset. B) If the vehicle has not had a previous Filter or Pump replacements please follow the following steps. 1. Please check the RDM for conditions a) and b). a) No external leakage visible. b) Rear Differential fluid level too high (overfilled). Use the Rear Axle Lubricant Level Inspection (Document ID: ) to check fluid level. The fluid level should be even with the bottom edge of the fill plug opening if not overfilled. If the rear differential fluid is too high drain the rear differential and replace the gear oil with the proper amount. Confirm that either the condition c) or d) exists. c) Differential Clutch fluid level low. Use the Differential Clutch Oil Inspection procedure (Document ID: ) to check fluid level. Fluid level should be level with the bottom of the differential clutch cover plug when fluid level is not low. d) Differential Clutch fluid level is OK but the current of the Differential Clutch Pump Motor Current is consistently below 2.5A (Diff Clutch Fluid level will NOT be OK if the pump motor current is consistently below 2.5A). Observe the current using the scan tool and monitoring the Rear Differential Clutch Pump Motor Current parameter. As the pump motor turns on/off the current will cycle from 0A to A if functioning normally. If conditions a) and b) exist and either condition c or d exists then differential clutch oil is leaking past the differential clutch internal seal (6 or 7 exploded view) into the rear differential. The service fix is to replace the Limited Slip Differential Clutch ONLY.

b) Leak from the Limited Differential Clutch pipes: replace leaking fitting and reattach pipe using a new clip. Refill differential clutch.

4 Page 4 of 5 2. Check the vehicle for external leakages. Below is a list of common leakages and suggestions for repair. a) Leak from the differential clutch oil cover: retighten bolts or replace gasket and refill differential clutch. b) Leak from the Limited Differential Clutch pipes: replace leaking fitting and reattach pipe using a new clip. Refill differential clutch. c) Leak from steel balls on the Differential Clutch: replace differential clutch assembly. Once a leak is corrected the Differential Clutch oil level should be confirmed with the Differential Clutch Oil Inspection procedure (Document ID: ). The Differential Clutch is properly filled when fluid level is level with the bottom of the differential clutch cover plug and Pump motor

5 Page 5 of 5 current is between A. Both conditions MUST be met for the differential clutch to be considered full. Follow the fill process in Procedure B if fluid needs to be added. See techlink article October 2010 for further clarification. Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information. WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION

Document ID: Some customers may comment that the service rear axle message is displayed on the driver information center (DIC).

Document ID: Some customers may comment that the service rear axle message is displayed on the driver information center (DIC). Page 1 of 14 Document ID: 2789612 #PI0703: Service Rear Message Displayed on Driver Information Center (DIC), DTC C0407 with Symptom Code 64 or C0403 with Symptom Code 62 Set - (Mar 20, 2012) Subject: