Circuit Description
The Throttle Position (TP) sensor circuit provides a voltage signal that changes relative to throttle blade angle. The signal voltage will vary from less than 1 volt at closed throttle to about 4 volts at Wide Open Throttle (WOT). The TP signal is one of the most important inputs used by the PCM for fuel control and most of the PCM-controlled outputs. The PCM monitors throttle position and compares actual throttle position from the TP sensor to a predicted TP value calculated from engine speed. If the PCM detects an excessively low TP sensor signal voltage, DTC P0122 will be set.
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
| • | TP sensor signal voltage is less than 0.1 volt. |
| • | Above conditions are present for greater than 10 second. |
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator lamp (MIL) during the first trip in which the diagnostic test has been run and failed. |
| • | The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed. |
| • | The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using a scan tool. |
Diagnostic Aids
Check for the following conditions:
| • | Poor connection at PCM. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection |
| • | Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the throttle position display on the scan tool while moving connectors and wiring harnesses related to the TP sensor. A change in the display will indicate the location of the malfunction. |
If DTC P0122 cannot be duplicated, the information included in the Fail Records data can be useful in determining vehicle mileage since the DTC was last set. If it is determined that the DTC occurs intermittently, performing the DTC P1122 Diagnostic Table may isolate the cause of the malfunction.
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table:
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board (OBD) Diagnostic System Check? | -- | ||
2 |
Important:: If DTC P1635 is set, refer to DTC P1635 5 Volt Reference Circuit first.
Does the scan tool indicate that the TP voltage parameter is less than the specified value? | 0.16V | ||
3 |
Does the scan tool indicate DTC P0122 failed? | -- | Go to Diagnostic Aids | |
4 |
Does the scan tool indicate that the TP voltage parameter is equal to the specified value? | 5V | ||
5 |
Does the voltage measure equal to the specified value? | 5V | ||
6 | Test the 5 volt reference circuit of the TP sensor for high resistance or an open and all 5 volt reference A circuits and connected components for a short to ground. Refer to Wiring Repairs . Did you find and correct the condition? | -- | ||
7 | Test the signal circuit of the TP sensor for a short to ground, a high resistance, or an open. Refer to Wiring Repairs . Did you find and correct the condition? | -- | ||
8 | Inspect for poor connections at the harness connector of the PCM. Refer to Intermittents and Poor Connections Diagnosis and Connector Repairs . Did you find and correct the condition? | -- | ||
9 | Inspect for poor connections at the harness connector of the TP sensor. Refer to Intermittents and Poor Connections Diagnosis and Connector Repairs . Did you find and correct the condition? | -- | ||
10 | Replace the TP sensor. Refer to Throttle Position Sensor Replacement . Did you complete the replacement? | -- | -- | |
|
Important: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Did you complete the replacement? | -- | -- | ||
12 |
Does the scan tool indicate DTC P0122 failed? | -- | System OK |
