Ford 2003 Mustang Workshop Manual page 4024

Retrieve/Clear Continuous DTCs
During vehicle operation, the restraints control module (RCM) will detect and store both intermittent
and hard fault DTCs in nonvolatile memory. The DTC strategy employed by the RCM incorporates a
time-out scheme for determining when a concern exists in the system. This requires a concern to exist
for up to one minute in the system before the RCM will detect it. For the RCM to determine that a
concern no longer exists, the concern must be absent for up to one minute. The actual detection time-
outs vary with each DTC. The DTCs can be retrieved with a scan tool. Any DTCs stored in the RCM
will be displayed on the scan tool along with a brief description of the DTC. If no DTCs are present, the
scan tool will display a SYSTEM PASSED message. This option can also be used to clear DTCs from
the RCM memory, as long as the concern no longer exists. Once 128 key cycles have been recorded
since the concern was last detected, the DTC will automatically be removed from memory.
To retrieve or clear DTCs, follow these steps.
1. Connect the scan tool to the data link connector (DLC).
2. Turn the ignition switch to the RUN position.
3. Follow manufacturer's instructions for the scan tool being used.
4. All continuous DTCs will be displayed. Before proceeding with the clearing operation, make
note of the DTCs displayed because, once cleared, they cannot be retrieved.
5. The scan tool will retrieve DTCs again after clearing DTCs and, if any remain, they will be
displayed. Hard DTCs will be redisplayed after clearing DTCs since they cannot be cleared from
the RCM.
On-Demand Self Test
The On-Demand Self Test option is used to verify that no electrical concerns exist with the air bag
supplemental restraint system (SRS). Upon entering the self test, the restraints control module (RCM)
will make an electrical check of each electrical component in the system. If a concern is detected, a
DTC is displayed on the scan tool with a brief description of the DTC. Concerns detected during the
self test are not stored in memory, unless the same concern was also detected during normal vehicle
operation. The self test should always be run after any repair to verify that the repair was successful.
To run the On-Demand Self Test, follow these steps:
6. Connect a scan tool to the data link connector (DLC).
7. Turn the ignition switch to the RUN position.
8. Follow manufacturer's instructions for the scan tool being used.
9. The RCM will run the On-Demand Self Test and display on-demand DTCs (reflecting hard
system concerns) on the screen.
PID/Data Monitor and Record
The PID/Data Monitor and Record option allows the scan tool operator to read the state of several
parameter IDs (PIDs) to aid in diagnosing the system. PIDs are real time measurements of parameters
such as voltages, resistances, etc., calculated by the restraints control module (RCM) and sent to the
scan tool for display. Many of the PIDs supported by the RCM are calculated periodically and are,
therefore, not true real time readings.
To retrieve PIDs, follow these steps:
1. Connect the scan tool to data link connector (DLC).