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 below 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. DTC P0122 will set when the PCM detects an excessively low signal voltage on the throttle position sensor signal circuit.
Conditions for Setting the DTC
| • | The ignition is ON. |
| • | TP sensor signal voltage is less than 0.16 volt. |
| • | Above conditions are present for longer than 1 second. |
Action Taken When the DTC Sets
| • | The PCM will illuminate the 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 Fail Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn the MIL OFF during the third consecutive trip in which the diagnostic has been 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 the scan tool Clear Information function or by disconnecting the PCM battery feed. |
Diagnostic Aids
Check for the following conditions:
| • | Poor connection at the PCM - Inspect harness connectors for the following conditions: |
| - | Backed out terminals. |
| - | Improper mating. |
| - | Broken locks. |
| - | Improperly formed or damaged terminals. |
| - | 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 fault. |
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 Chart may isolate the cause of the fault.
Test Description
Number(s) below refer to the Step number(s) on the Diagnostic Table:
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||
2 |
Is TP Sensor display less than the specified value? | 0.16V | ||
3 |
Does the scan tool indicate DTC P0122 failed? | -- | Refer to Diagnostic Aids | |
4 |
Is TP Sensor at the specified value? | 5V | ||
5 |
Is TP Sensor at the specified value? | 5V | ||
6 |
Is the 5 volt reference A circuit open or shorted to ground? | -- | ||
7 | Check the 5 volt reference A circuit for a poor connection at the PCM and replace terminal if necessary. Refer to Electrical Diagnosis. Did the terminal require replacement? | -- | ||
8 |
Was a problem found? | -- | ||
9 |
Was the TP signal circuit open or shorted to ground? | -- | ||
10 |
Did the terminal require replacement? | -- | ||
11 | Check the TP sensor signal and 5 volt reference circuits for a poor connection at the TP sensor and replace terminal(s) if necessary. Refer to Wiring Repairs in Electrical Diagnosis. Did either terminal require replacement? | -- | ||
12 | Replace the TP sensor. Refer to Throttle Position Sensor Replacement Is the action complete? | -- | -- | |
Replace the PCM. Important: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming Is the action complete? | -- | -- | ||
14 |
Does the scan tool indicate DTC P0122 failed? | -- | System OK |
