Circuit Description
The throttle position (TP) sensor is a potentiometer. The powertrain control module (PCM) supplies the TP sensor a reference voltage, a signal, and ground circuits. When the throttle is depressed, the TP sensor signal rises to near the reference voltage. When the throttle is released, the TP sensor signal decreases from the reference voltage. The control module monitors the TP sensor signal circuit voltage in order to determine the throttle blade angle, or opening.
This diagnostic trouble code (DTC) is designed to detect a TP sensor signal voltage higher than the possible operating range of a normally functioning TP sensor.
Conditions for Running the DTC
The engine is running.
Conditions for Setting the DTC
The TP sensor signal voltage is more than 4.7 volts for 1 second or more.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Diagnostic Aids
The scan tool reads the throttle position in volts. The scan tool should read between 0.45-0.85 volt with the throttle closed and the ignition switch turned ON or at idle. The voltage should increase at a steady rate as the throttle is moved toward the wide open throttle (WOT) position.
The scan tool will read the throttle angle percentage. 0 percent equals closed throttle. 100 percent equals wide open throttle (WOT).
Scan the TP sensor while depressing the accelerator pedal with the engine turned OFF and the ignition turned ON. The display should vary from less than 1.25 volts (1,250 mV) with the throttle closed to more than 4.5 volts (4,500 mV) when the throttle is held at the WOT position.
This DTC will result if the TP ground circuit is open or the TP sensor signal circuit is shorted to voltage. Refer to Symptoms - Engine Controls .
An intermittent may be caused by any of the following conditions:
| • | A poor connection |
| • | Rubbed through wire insulation |
| • | A broken wire inside the insulation |
Thoroughly inspect any circuitry that is suspected of causing the intermittent complaint. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
If a repair is necessary, refer to Wiring Repairs or Connector Repairs in Wiring Systems.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
If the TP signal measures more than 4.8 volts, then the condition exists.
-
With the TP sensor disconnected, and if the PCM and the wiring are okay, the TP signal should go below 0.25 volt. This test could set a DTC P0122.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 |
Important: Before clearing the DTCs, use the scan tool Capture Info to save the Freeze Frame and Failure Records for reference. The control modules data is deleted once the Clear Info function is used. Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
Does the scan tool display a TP sensor voltage more than the specified value? | 4.7 V | Go to Step 3 | Go to Step 4 | |
Does the scan tool display a TP sensor voltage less than the specified value? | 0.25 V | Go to Step 5 | Go to Step 8 | |
4 | The DTC is intermittent. Are any additional DTCs stored? | -- | Go to Diagnostic Aids | |
5 | Measure the 5-volt reference circuit at the TP sensor harness connector with a DMM connected to a ground. Is the voltage more than the specified value? | 5.2 V | Go to Step 9 | Go to Step 6 |
6 | Probe the TP sensor ground circuit at the TP sensor harness connector with a test lamp connected to B+. Is the test lamp ON? | -- | Go to Step 7 | Go to Step 11 |
7 | Replace the TP sensor. Refer to Throttle Position Sensor Replacement . Is the action complete? | -- | Go to Step 15 | -- |
8 | Check for a short to voltage in the TP sensor signal circuit. Did you find a problem? | -- | Go to Step 12 | Go to Step 14 |
9 |
Is the voltage more than the specified value? | 0 V | Go to Step 13 | Go to Step 10 |
10 | Measure the voltage on the MAP sensor 5-volt reference circuit at the PCM C3 connector with a DMM connected to a ground. Is the voltage more than the specified value? | 0 V | Go to Step 13 | Go to Step 14 |
11 | Repair the open in the TP sensor ground circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 15 | -- |
12 | Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 15 | -- |
13 | Repair the short to voltage on the 5-volt reference circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 15 | -- |
14 |
Is the action complete? | -- | Go to Step 15 | -- |
15 |
Does the scan tool indicate the diagnostic Passed? | -- | Go to Step 16 | Go to Step 2 |
16 | Does the scan tool display any additional undiagnosed DTCs? | -- | System OK | |
