Powertrain Controls - ECM/PCM

DTC 55 Chart:

CIRCUIT DESCRIPTION
The Throttle Position (TP) sensor is "self adjusting." When the ignition is turned "OFF," the PCM executes a TP sensor learning routine. After key "OFF," the PCM will retract the ISC until the ISC throttle position switch opens and the throttle lever is resting on the minimum air screw. At that time, the PCM stores the TP sensor value and calculates a correction. If the same correction factor occurs on two consecutive key "OFF" cycles, the TP sensor is then corrected to 0 degrees using the correction factor "Learned." If the value needs correction by more than ± 6.50 degrees, DTC 55 will set and be stored in memory at the next key "ON" cycle.

DTC 55 WILL SET WHEN
Learned TP sensor correction is 6.50 degrees or greater.

ACTION TAKEN (PCM WILL DEFAULT TO)
- The PCM learned TP sensor value set to 0.
- With a current DTC 55 set, the PCM will illuminate the Malfunction Indicator Lamp (MIL) (Service Engine Soon).
- Current DTC will clear when fault no longer exists and the ignition is cycled.
- History DTC will clear after 50 ignition cycles.

DTC 55 WILL CLEAR WHEN
The fault no longer exists and the ignition switch is cycled "OFF" and "ON."

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.

1. Checking for ISC or TP sensor codes which could cause DTC 55.
2. Checking if TP sensor is really out of range or the throttle position switch is open causing it to look that way.
3. Checking TP sensor adjustment. TP sensor displays uncorrected TP sensor so that it can be used to check TP sensor adjustment.
4. If TP sensor is within range, ISC and throttle switch operation need to be thoroughly checked. The throttle linkage needs to be checked for proper operation, throttle and cruise cables not binding, throttle shaft and blades not binding.