Pinpoint Test A: Grinding / Moan / Drone From Transfer Case In 2H Only

WARNING: This page is about a different car, the 2021 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.

Normal Operation and Fault Conditions
All gear boxes, including the transfer case, generate some noise during normal operation. Some normal noises may be perceived as severe when the vehicle is raised on a hoist and the listener is closer to the transfer case.

In 2H mode, the transfer case input shaft / planetary carrier is connected directly to the rear output shaft via the reduction hub. The only loaded components are the input shaft bearing and rear output shaft bearing. All other components are stationary or are allowed to freewheel unloaded. Any noise generated by the input or output shaft bearings will be present in all 4WD modes of operation.

Noise heard from the transfer case only in 2H mode is mostly likely originating from the front axle components. In 2H mode, a worn or damaged wheel hub to halfshaft bearing can produce noise only heard in 2H mode. If only one IWE is engaged, the motion induced into the front differential and front driveline can produce noises inside the transfer case. Electronic shift transfer cases will produce a drone type of noise when one IWE is engaged and the other is disengaged.

Possible Sources
- Normal gearbox noise
- Wheel hub to front halfshaft bearing worn or damaged
- One IWE stuck engaged

A1 COMPARE TO LIKE UNIT
- Compare the noise to a similar vehicle. Use an NVH analyzer or a decibel meter app to quantify the noise volume/intensity. When selecting a comparable vehicle, attempt to match:
  - transfer case design (electronic shift, torque on demand, etc.)
  - vehicle build configuration (XL, Lariat, Supercrew, regular cab
  - tire brand, size, and condition
  - vehicle mileage and condition
  - NVH analyzer sensor or decibel meter location
  - vehicle location / environment (wall or building proximity, weather or environmental conditions)
Is the noise in the subject vehicle similar to the noise from the comparable vehicle?

Yes This a characteristic of the vehicle. Do not attempt any repairs for this condition.

No GO to A2

A2 CHECK FRONT DRIVELINE

Road test the vehicle in 2H mode for 2 mi (3 km) to complete front axle warm up strategy. Do not shut off the ignition.

Continue road test by driving under conditions that duplicate the customer concern.

When the concern is present, shift the vehicle to 4H (or 4A) mode.

Was the concern only present in 2H and gone in 4H (or 4A) modes?

Yes	The noise concern is originating in the front axle. Do not shut off the ignition. GO to A3

See Symptom Chart - NVH for additional symptoms. For 2-Speed Torque on Demand Transfer Case, REFER to: Four-Wheel Drive Systems - Vehicles With: 2-Speed Torque On Demand Transfer Case . For Electronic Shift Transfer Case, REFER to: Four-Wheel Drive Systems - Vehicles With: Electronic Shift Transfer Case .

A3 CHECK FOR LH (LEFT-HAND) AND RH (RIGHT-HAND) IWE (INTEGRATED WHEEL END) DISENGAGEMENT

NOTE: The ignition must remain in the Run position from the previous test. If the ignition was turned off, repeat the 2 mi (3 km) road test to complete the axle warm up strategy.

With the vehicle in N, position it on a hoist. Raise the vehicle until all 4 wheels are off the ground. REFER to: Jacking and Lifting - Overview .

Select ATCM mode 2H

Rotate the LH front tire one revolution forward and one revolution backward while observing the LF halfshaft.

Rotate the RH front tire one revolution forward and one revolution backward while observing the RF halfshaft.

Did both halfshafts remain stationary?

Yes

GO to A4

If only the LHIWE rotated, follow diagnostics for C06A1:92. REFER to: Four-Wheel Drive Systems - Vehicles With: 2-Speed Torque On Demand Transfer Case . REFER to: Four-Wheel Drive Systems - Vehicles With: Electronic Shift Transfer Case . If only the RHIWE rotated, follow diagnostics for C06A2:92. REFER to: Four-Wheel Drive Systems - Vehicles With: 2-Speed Torque On Demand Transfer Case . REFER to: Four-Wheel Drive Systems - Vehicles With: Electronic Shift Transfer Case .

A4 CHECK FOR LH (LEFT-HAND) AND RH (RIGHT-HAND) IWE (INTEGRATED WHEEL END) ENGAGEMENT

Vehicle on hoist with all 4 wheels are off the ground.

Select ATCM mode 4H or 4A

Rotate the LH front tire one revolution forward and one revolution backward while observing the LF halfshaft.

Rotate the RH front tire one revolution forward and one revolution backward while observing the RF halfshaft.

Did both halfshafts rotate?

Yes

If the LHIWE did not rotate, follow diagnostics for C06A1:92. REFER to: Four-Wheel Drive Systems - Vehicles With: 2-Speed Torque On Demand Transfer Case . REFER to: Four-Wheel Drive Systems - Vehicles With: Electronic Shift Transfer Case . If the RHIWE did not rotate, follow diagnostics for C06A2:92. REFER to: Four-Wheel Drive Systems - Vehicles With: 2-Speed Torque On Demand Transfer Case . REFER to: Four-Wheel Drive Systems - Vehicles With: Electronic Shift Transfer Case .