ECM Code EO55, TPS Out Of Adjustment: Action:

At next key on, the ECM will see TPS out-of-adjustment flag, and set Code EO55 as current. No diagnostic light or service message will appear.

The TPS is self-adjusting. With key off, the ECM executes a TPS learning routine. After turning key off, the ECM will retract ISC until the ISC throttle switch opens and throttle linkage is resting on the minimum air screw. At that time, the ECM stores the TPS value and calculates a correction.

If the same correction factor occurs on 2 consecutive key off cycles, the TPS is corrected to zero degrees using correction factor learned. If value needs correction by more than -2.9 degrees or +3.0 degrees, Code EO55 will be stored in memory at next key on cycle. Parameter ED01 displays uncorrected TPS values.

NOTE: Test numbers refer to test numbers on diagnostic chart.

Test Number 1) This steps checks for TPS adjustment. ECM parameter ED01 displays uncorrected TPS so that it can be used to check TPS adjustment.

Test Number 2) If this reading is obtained, TPS adjustment is okay.

Test Number 3) If TPS adjustment is okay, ISC and throttle switch operation need to be thoroughly checked. The throttle linkage needs to be checked for proper operation, throttle and cruise cables, and throttle valve cables not binding, proper throttle return spring operation, and throttle shaft and blades free to move.