Powertrain Controls - ECM/PCM

DTC 22 Throttle Position (TP) Sensor Circuit (Signal Voltage Low):

Throttle Position (TP) Sensor Schematic:

CIRCUIT DESCRIPTION
The Throttle Position (TP) sensor provides an output voltage relative to throttle position angle. The Powertrain Control Module (PCM) supplies a 5 volt reference and a ground to the TP sensor and monitors the voltage returned. The TP sensor voltage will vary from about 0.2V to 0.9v at idle or with ignition "ON" and engine "OFF" to over 4.5V at wide open throttle.

DIAGNOSTIC TROUBLE CODE (DTC) 22 WILL SET WHEN
^ TP sensor signal voltage is less than 0.21 volt.
^ Engine run time is greater than 5 seconds.

ACTION TAKEN (PCM WILL DEFAULT TO)
The Malfunction Indicator Lamp (MIL) will illuminate. If the Vehicle speed Sensor (VSS) reads less than 2 mph, the TP sensor will default to 0%. If VSS reads greater than 2 mph, the TP sensor will default to 10%. The cooling fan will enable.

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

1. The TP sensor has an auto zeroing feature. If the voltage reading is within the range of 0.2 to 0.9 volt, the PCM will use that value as closed throttle. If the voltage reading is out of the auto zero range at closed throttle, check for a binding throttle cable or damaged linkage, if OK, continue with diagnosis.
2. Simulates DTC 21 (high voltage). If the PCM recognizes the high signal voltage then the PCM and wiring are OK.
3. Check for a good connection. If connection is good, replace TP sensor.
4. This simulates a high signal voltage to check for an open in CKT 417. The Tech 1 scan tool will not read up to 12 volts, but what is important is that the PCM recognizes the signal on CKT 417.

DIAGNOSTIC AIDS
^ Scan TP sensor while depressing accelerator pedal with engine "OFF" and ignition "ON." Display should vary from 0.2V when throttle is closed, to over 4.5V when throttle is held wide open.
^ If DTC 21 and 23 are also set, check CKT 452 for faulty wiring or connections.
^ If DTCs 22, 34 and 66 are also set check CKT 474 for a short to ground.
^ Check condition of connector and sensor terminals for moisture or corrosion, and clean or replace as necessary. If corrosion is found, check condition of connector seal and repair or replace if necessary.
^ Refer to "Intermittents," in Diagnosis by Symptom. - Intermittent Malfunctions