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 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 MIL 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. |
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 Chart 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 |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
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? | -- | Go 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 Diagnois. Did the terminal require replacement? | -- | ||
8 |
Was the TP signal circuit open or shorted to ground? | -- | ||
9 | Check the TP sensor signal circuit for a poor connection at the PCM and replace terminal if necessary. Refer to Electrical Diagnois. Did the terminal require replacement? | -- | ||
10 | Check the TP sensor signal circuit for a poor connection at the TP sensor and replace terminal if necessary. Refer to Electrical Diagnois. Did the terminal require replacement? | -- | ||
11 | Replace the TP sensor. Refer to Throttle Position Sensor Replacement . Is th eaction complete? | -- | -- | |
Replace the PCM. Important: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | ||
13 |
Does the scan tool indicate DTC P0122 failed? | -- | System OK | |
