Some 2013-2018 Lincoln Navigator vehicles equipped with 4WD may exhibit an intermittent grinding noise while driving in 2-wheel drive mode, most commonly on acceleration.
This may be due to a loss of vacuum to the integrated wheel end (IWE) actuators and/or wear of the IWE components.
To correct the condition, follow the service procedure steps to reprogram the transfer case control module (TCCM) and replace any worn vacuum and/or IWE components.
1. If the vehicle is a 2018 Navigator built on or before Sept. 17, 2018, reprogram the TCCM using the latest version of the appropriate scan tool.
2. If not a 2018 built as stated earlier, inspect the IWE vacuum hoses. If any hoses are disconnected or damaged, reconnect or replace as needed.
3. Replace the vacuum check valve located near the vacuum reservoir.
4. Disconnect the vacuum line to the IWE at the vacuum solenoid.
5. Connect a hand vacuum pump to the IWE vacuum supply line and apply 20 in-Hg of vacuum.
Does the vacuum drop more than 0.5 in-Hg per minute? If yes, proceed to Step 6. If no, connect the IWE vacuum supply line to the solenoid and proceed to Step 10.
6. Using a hand vacuum pump, apply 20 in-Hg of vacuum to each IWE, one at a time, and monitor the vacuum gauge. If the vacuum drops more than 0.5 in-Hg per minute, proceed to Step 8. If not, proceed to Step 7.
7. Replace the vacuum lines between the solenoid and IWEs.
8. Remove the IWE from the affected wheel.
9. Inspect the wheel bearing splines for damage or excessive wear. If damaged or worn, replace the IWE assembly and wheel bearing. If not, replace the IWE assembly.
10. Test the IWE vacuum supply lines. Disconnect the vacuum supply line at the left or right IWE and connect a vacuum gauge to the supply line. Start the engine and allow it to idle for 5 minutes to build vacuum. Connect the scan tool and enter TCCM datalogger. Active-command the vacuum solenoid. Repeat this test on the opposite IWE vacuum supply line.
11. Is the vacuum at both left and right supply lines greater than 10 in-Hg? If yes, proceed to Step 12. If no, replace the vacuum lines between the solenoids and IWEs.
12. Road test for noise by performing heavy acceleration in 2WD. Engage the 4WD system to verify proper engagement/disengagement quality. Is a grinding noise present in 2WD that is not present in 4WD? If yes, proceed to Step 13. If no, the repair is complete.
13. Remove the IWE assembly from the affected wheel.
14. Inspect the wheel bearing splines for damage/wear. If damage/wear is evident, replace the IWE clutch ring and wheel bearing. If no damage/excessive wear is found, replace the IWE clutch ring.
