Ford 2003 Mustang Workshop Manual page 110

M4 INSPECT THE FRONT DRIVESHAFT
NOTE: Verify that the driveshaft and pinion flange index marks
are aligned.
Inspect the front driveshaft for missing weights, damage or
undercoating.
Inspect the U-joints and slip yoke for freedom of movement.
Check driveshaft runout and, if necessary, check the pinion
flange runout.
Is the driveshaft or U-joints worn or damaged?
M5 ROAD TEST WITH THE FRONT DRIVESHAFT ONLY
NOTE: Index mark the driveshaft to the pinion flange and to the
output shaft before removal.
Remove the rear driveshaft.
Plug the transfer case with an output shaft seal plug.
NOTE: Shift the transfer case into 4WD high so the vehicle is
driven by the front driveshaft only.
Test drive the vehicle.
Is the vibration gone?
M6 ROAD TEST WITH THE REAR DRIVESHAFT ONLY
NOTE: Index mark the front driveshaft to the pinion flange.
Remove the front driveshaft.
Test drive the vehicle.
Is the vibration gone?
M7 TRANSFER CASE TAIL SHAFT INSPECTION
Inspect the splines of the output shaft for wear or damage.
Inspect the splines of the driveshaft slip yoke for wear or
damage.
Are the splines worn or damaged?
Component Tests
Idle Air Control (IAC) Valve
1. Open the hood.
2. NOTE: Key symptom is elevated idle speed while noise is occurring.
NOTE: "Snapping" the throttle can induce the noise.
Verify the condition by operating the vehicle for a short time.
3. Inspect the IAC valve. If physical evidence of contamination exists, install a new IAC valve.
GO to M4 .
Yes
REPAIR or INSTALL a
new driveshaft as
necessary. TEST the
system for normal
operation.
No
GO to M5 .
Yes
INSTALL and BALANCE
the rear driveshaft.
TEST the system for
normal operation.
No
GO to M6 .
Yes
INSTALL and BALANCE
the front driveshaft.
TEST the system for
normal operation.
No
GO to M7 .
Yes
REPAIR or INSTALL
new components as
necessary. TEST the
system for normal
operation.
No
The transfer case is OK.
CONDUCT a diagnosis
on other suspect
systems.