P055

DTC P055:

IAT, MAP And TPS Circuits:

CIRCUIT DESCRIPTION
The Throttle Position (TP) sensor on the PFI engine is self adjusting. When the ignition is turned "OFF," the Powertrain Control Module (PCM) executes a TP sensor learning routine. After key "OFF," the PCM will retract the Idle Speed Control (ISC) motor 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 (+/-) 6.5 degrees, PCM Code P055 will be stored in memory at the next key "ON" cycle. Note: Parameter PD01 displays uncorrected TP sensor values.

TEST CONDITION
Test continuously.

FAILURE CONDITION
Learned TP sensor correction 6.5 degrees or greater.

ACTION TAKEN
PCM learned TP sensor value set to 0.

NOTES ON FAULT TREE
1. Checking for ISC/TP sensor codes which could cause Code P055.
2. Checking if the TP sensor is really out of range or if the throttle position switch is open causing it to look that way.
3. Checking TP sensor adjustment. PCM Data PD01, 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, proper throttle return spring operation, and that throttle shaft and blades are free to move.