Circuit Description
This diagnostic monitors the TP sensor 1 signal. There are two TP sensors located on the throttle body inside of the throttle actuator control (TAC) module. All throttle control is performed by the throttle actuator control (TAC) system. The TP sensors, along with the accelerator pedal position (APP) sensors and the TAC module are mandatory components of the TAC system. The TP sensors are used to determine the throttle plate angle. The TP sensor is a potentiometer with a resistance value that changes along with the throttle valve position. The sensor uses a 5-volt reference supply, a low reference and a signal circuit. The TAC module uses the signal circuit voltage to calculate the actual throttle valve opening. The TP sensor is an integral part of the TAC module and is not serviced separately. Installing a new TP sensor requires the replacement of the throttle body assembly. For additional information on the operation of the TP sensor and the TAC system refer to Throttle Actuator Control (TAC) System Description . If the TAC module detects that the TP sensor 1 signal voltage is too low it reports the malfunction to the PCM and the PCM sets this DTC.
DTC Descriptors
This diagnostic procedure supports the following DTC.
DTC P0122 Throttle Position (TP) Sensor 1 Circuit Low Voltage
Conditions for Running the DTC
| • | DTC P0123 is not set. |
| • | DTC P0122 runs continuously once the above conditions are met. |
Conditions for Setting the DTC
| • | The TP sensor 1 voltage is 0.28 volts or less. |
| • | The above condition is present for less than 1 second. |
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Freeze Frame and/or Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A last test failed, or current DTC, clears when the diagnostic runs and does not fail. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Use a scan tool in order to clear the MIL and the DTC. |
Test Description
The numbers below refer to the step numbers in the diagnostic table.
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The Diagnostic System Check-Engine Controls prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool, if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
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This step determines if a fault is present. The normal TP angle at engine speeds above idle is more than 0 percent.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views | ||||
Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | ||
Did the TP sensor 1 angle remain fixed at the specified value at all engine speeds? | 0% | Go to Step 4 | Go to Step 3 | |
3 |
Is DTC P0122 set? | -- | Go to Step 4 | Go to Intermittent Conditions |
4 | Replace the throttle body. Refer to Throttle Body Assembly Replacement . Did you complete the replacement? | -- | Go to Step 5 | -- |
5 |
Does the DTC run and pass? | -- | Go to Step 6 | Go to Step 2 |
6 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
