P0122

Throttle Position (TP) Sensor Circuit:

Circuit Description
The Powertrain Control Module (PCM) supplies a 5V reference and a ground to the sensor. The Throttle Position (TP) sensor sends a voltage signal back to the PCM relative to throttle blade opening. The TP sensor signal voltage will vary from 0.45V at closed throttle to over 4.5V at wide open throttle.

Conditions For Setting The DTC
- The TP sensor reads less than 0.19V.
- The engine is running.

Action Taken When the DTC Sets
- The Malfunction Indicator Lamp (MIL) will illuminate.
- The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers.
- A history DTC is stored.
- The TP angle will default to 0% when the vehicle speed is less than 2 mph. The TP angle will default to 10% when the vehicle speed is greater than 2 mph. The scan tool will show the defaulted value.

Conditions for Clearing the MIL/DTC
- The MIL will turn "OFF" after three consecutive ignition cycles in which the diagnostic runs without a fault.
- A history DTC will clear after 40 consecutive warm up cycles without a fault.
- DTCs can be cleared by using a scan tool.

Diagnostic Aids
Whenever a DTC P0122 cannot be duplicated, use the information included in the "Freeze Frame" data to evaluate the conditions when the DTC set.

DTC P0122 - Throttle Position (TP) Sensor Circuit Low Voltage:

Test Description
Numbers below refer to the step numbers on the Diagnostic Table.
1. The OBD System Check prompts the Technician to complete some basic checks and store the Freeze Frame Data and the Failure records on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. This information on the scan tool can be referred to later.
2. The TP sensor has an auto zeroing feature. Whenever the voltage reading is between 0.20V and 0.90V, the PCM will automatically assume this as closed throttle position.
4. Whenever the PCM recognizes a high voltage signal, then the PCM and wiring are OK.
5. This simulates a high voltage signal which will identify an open in the signal circuit.
8. Whenever the test light illuminates while probing the TP signal circuit, then the TP signal circuit is shorted to ground.
11. Before replacing the PCM, check terminals for improper mating, broken locks, or physical damage to the wiring harness. Replacement PCM must be reprogrammed. Refer to the latest Techline information for programming procedures.