Symptom Chart(s)

Diagnostics in this service information assume a certain skill level and knowledge of Ford-specific diagnostic practices. REFER to: Diagnostic Methods .

In most circumstances the PCM sets a DTC to help guide with diagnostics. Refer to the DTC Chart before using the Symptom Chart. The Condition column lists the vehicle condition. The Possible Sources column lists a detailed vehicle condition. The Action column lists the action to be performed to determine the cause of the condition. Each action lists the components that can cause the system and the individual components in that system. The components are listed in order of disassembly. Use the list of components and the required action to focus on disassembly inspections for the root cause of the concern.

Symptom Chart

Condition	Possible Sources	Actions
The power transfer unit makes noise	Tire inflation pressure	MAKE SURE all tires and wheels inflation pressures are correct.
	Tire and wheel size	MAKE SURE all tires and wheels are the same size and brand.
	Fluid level	FILL with the correct type and amount of lubricant. REFER to: Transfer Case Fluid Level Check .
	Internal components	OPERATE the vehicle in all gears. If there is noise in the transmission in NEUTRAL, or in some gears and not in others, REMOVE and REPAIR the transmission. If there is noise in all gears, INSTALL a new power transfer unit. REFER to: Transfer Case .
Leaking fluid from the power transfer unit vent	Power transfer unit is over filled	Drain the fluid to the correct level. REFER to: Transfer Case Fluid Level Check .
Leaking automatic transmission fluid	Power transfer unit intermediate shaft seal	REFER to Analysis of Leakage in this procedure below.
	Power transfer unit compression seal	REFER to Analysis of Leakage in this procedure below.
	Power transfer unit intermediate shaft bushing	REFER to Analysis of Leakage in this procedure below.
Leaking gear lubricant from the seals	The power transfer unit vent is plugged (located on top of the power transfer unit)	INSTALL a new power transfer unit vent. REFER to: Transfer Case Vent .
Leaking gear lubricant from the seals	Damaged seals	Replace leaking seal. REFER to: Transfer Case Input Shaft Seal LH . REFER to: Transfer Case Input Shaft Seal RH . REFER to: Transfer Case Rear Seal . REFER to: Intermediate Shaft Seal .
Vehicle has no or inadequate torque at rear wheels	Rear Drive Unit failure	REFER to: Rear Drive Axle and Differential .
Vehicle has no or inadequate torque at rear wheels	Power transfer unit mechanical failure	INSTALL a new power transfer unit. REFER to: Transfer Case . REFER to: Transfer Case .
Vehicle binds in a turn or resists turning/pulsates or shudders in a straight line	Wheels/tires	REFER to: Wheels and Tires .
	Brake system	REFER to: Brake System .
	Wheel bearings	REFER to: Suspension System .
	Halfshafts	REFER to: Front Drive Halfshafts . REFER to: Rear Drive Halfshafts .
	ABS system	REFER to: Anti-Lock Brake System (ABS) and Stability Control .
Loss of AWD function or partial AWD function	Power transfer unit overheating	INSPECT the duct that cools the power transfer unit sump is free and clear of debris.

NOTE: Inspection of the seal's mating journal should be performed every time a seal is replaced. The mating part/journal should be replaced if it has any of the following conditions: Radial wear groove that is felt by running a finger nail across where the seal lip runs. Scratches, pitting, galling, nicks or other shaft damage under or near where the seal lip runs. Discoloration or coked oil on the shaft where the seal lip runs. Shaft corrosion under or near where the seal lip runs. Sharp edges or burrs on the shaft lead in chamfer. NEVER use emery cloth on journal finishes, replace the part.

Analysis of Leakage

The power transfer unit may leak different color fluids, automatic transmission fluid and a brown/black gear lube for power transfer unit fluid. The power transfer unit seals prevent these types of fluids from leaking. Its important to note the color of fluid leaking to determine the most appropriate service procedure.

NOTE: Remove and replace leaking seals using the information found in the Input Shaft Seal or Cover Seal replacement procedure. The specified tools called out in this procedure allows seal replacement without causing damage to the power transfer unit casing/drive gear.

NOTE: Replace the intermediate shaft seal any time the intermediate shaft is removed.

Power Transfer Unit Leaks From the RH Side

If the leak is automatic transmission fluid, the intermediate shaft seal needs to be replaced. REFER to: Intermediate Shaft Seal .

If the leak is brown/black gear lube at the case to cover seam, the power transfer unit input shaft seal - RH seal and cover O-ring needs to be replaced. REFER to: Transfer Case Input Shaft Seal RH .

Power Transfer Unit Leaks From the LH Side

If the leak is automatic transmission fluid, the LH halfshaft seal and compression seal needs to be replaced. REFER to: Halfshaft Seal RH - AWD . REFER to: Transfer Case .

If the leak is brown/black gear lube replace the LH input shaft seal and the compression seal. REFER to: Transfer Case Input Shaft Seal LH .

Power Transfer Unit Leaks From the Rear

If the leak is brown/black fluid, the Pinion Flange Seal/Rear Seal needs to be replaced. REFER to: Transfer Case Rear Seal .

Power Transfer Unit Leaks From the Top Vent

If equipped with a vent hose, check for a missing or disconnected hose. REFER to: Transfer Case Vent . If the PTU vent hose is present and attached correctly, check the PTU fluid level. If the PTU fluid is overfilled, replace the intermediate shaft seal, LH input shaft seal and the RH input shaft seal. REFER to: Transfer Case Input Shaft Seal LH . REFER to: Transfer Case Input Shaft Seal RH . REFER to: Intermediate Shaft Seal .