P0123

Throttle Position (TP) Sensor Circuit:

Circuit Description
The Powertrain Control Module (PCM) supplies a 5V reference and a ground to the sensor. The TP sensor sends a voltage signal back to the PCM relative to throttle blade opening. The Throttle Position (TP) sensor signal voltage will vary from 0.2V at closed throttle to over 4.5V at wide open throttle. The TP sensor is one the most important sensor in the control of fuel delivery.

Conditions For Setting The DTC
- The TP sensor voltage is greater than 3.9V for 5 seconds.
- The engine speed is less than 1500 RPM.
- The MAP sensor is less than 65 kPa (0.33V).
- One or both of the following DTCs are not set P0107, P0108.

OR

- The TP sensor voltage is greater than 4.8V.
- One or both of the following DTCs are not set P0107, P0108.

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
- With the ignition "ON" and the throttle at closed position, the voltage should read between 0.20V and 0.90V and increase steadily to over 4.5V at wide open throttle.
- Check the connectors for proper mating, replace or repair as necessary.

DTC P0123 - Throttle Position (TP) Sensor Circuit - High Input:

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. When the throttle is closed, the TP sensor voltage should read less than 0.90V. When the TP sensor voltage does not read less than 0.90v check for a binding or sticking throttle cable.
5. Probing the ground circuit with a test light checks the circuit for high resistance which will cause a DTC P0123 to set.
7. A shorted 5 volt reference circuit may also set additional DTCs.
11. Before replacing the PCM, check terminals for improper mating, broken locks, or physical damage to the wiring harness. Replacement PCM must be reprogrammed.