Ford 2003 Mustang Workshop Manual page 52

Did any abnormal occurrence coincide with or proceed its appearance?
Use the information gained from the customer to accurately begin the diagnostic process.
Pre-Drive Check
It is important to do a pre-drive check before road testing the vehicle. A pre-drive check verifies that
the vehicle is relatively safe to drive and eliminates any obvious faults on the vehicle.
The pre-drive check consists of a brief visual inspection. During this brief inspection, take note of
anything that will compromise safety during the road test and make those repairs/adjustments before
taking the vehicle on the road.
Preparing for the Road Test
Observe the following when preparing for the road test:
Review the information recorded on the NVH Diagnostic Guide. It is important to know the
specific concern the customer has with the vehicle.
Do not be misled by the reported location of the noise/vibration. The cause can actually be
some distance away.
Remember that the vibrating source component (originator) may only generate a small
vibration. This small vibration can in turn cause a larger vibration/noise to emanate from another
receiving component (reactor), due to contact with other components (transfer path).
Conduct the road test on a quiet street where it is safe to duplicate the vibration/noise. The ideal
testing route is an open, low-traffic area where it is possible to operate the vehicle at the speed
in which the condition occurs.
If possible, lower the radio antenna in order to minimize turbulence. Identify anything that could
potentially make noise or be a source of wind noise. Inspect the vehicle for add-on items that
create vibration/noise. Turn off the radio and the heating and cooling system blower.
The engine speed is an important factor in arriving at a final conclusion. Therefore, connect an
accurate tachometer to the engine, even if the vehicle has a tachometer. Use a tachometer that
has clearly defined increments of less than 50 rpm. This ensures an exact engine speed
reading.
Verify the Customer Concern
Verify the customer concern by carrying out a road test, an engine run-up test, or both.
The decision to carry out a road test, an engine run-up test, or both depends on the type of NVH
concern. A road test may be necessary if the symptom relates to the suspension system or is sensitive
to torque. A drive engine run-up (DERU) or a neutral engine run-up (NERU) test identifies noises and
vibrations relating to engine and drivetrain rpm. Remember, a condition will not always be identifiable
by carrying out these tests, however, they will eliminate many possibilities if carried out correctly.
Road Test