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 1.0 volts at closed throttle to above 4.0 volts at Wide Open Throttle (WOT).
If the PCM detects an excessively high TP Sensor voltage, DTC P0123 will be set.
Conditions for Running the DTC
The ignition is on.
Conditions for Setting the DTC
| • | TP sensor signal voltage is greater than 4.9 volts. |
| • | The above conditions present for more than 10 seconds. |
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive 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. Use a corresponding mating terminal to test for proper tension. Refer to Intermittents and Poor Connections Diagnosis , Repairing Connector Terminals and Connector Repairs . |
| • | Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the TP sensor 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. Refer to Wiring Repairs . |
| • | Faulty TP sensor: With the key on, engine off, observe the TP sensor display on the scan tool while slowly depressing the accelerator to wide open throttle. If a voltage over 4.90 volts is seen at any point in normal accelerator travel, replace the TP sensor. |
If DTC P0123 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 P1121 Throttle Position (TP) Sensor Circuit Intermittent High Voltage diagnostic may isolate the cause of the fault.
Test Description
The numbers below refer to the step numbers on the Diagnostic Table:
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain on-Board Diagnostic Check performed? | -- | ||
2 |
Is TP Sensor above the specified value? | 4.9V | ||
3 |
Does scan tool indicate DTC P0123 failed this ignition? | -- | Go to Diagnostic Aids | |
4 |
Is the TP Sensor near the specified value? | 0.0V | ||
5 | Probe the sensor ground circuit at the TP sensor harness connector with a J 35616-200 test light connected to battery positive voltage. Is the J 35616-200 test light on? | -- | ||
6 |
Was the TP sensor signal circuit shorted? | -- | ||
Does disconnecting any of these components cause the TP Sensor display to change? | -- | |||
8 |
Was the 5 Volt Reference A circuit shorted? | -- | ||
9 | Check for poor electrical connections at the TP sensor and PCM and replace terminals if necessary or open sensor ground circuit. Refer to Testing for Continuity , Intermittents and Poor Connections Diagnosis , Repairing Connector Terminals and Connector Repairs . Did any terminals or ground circuit require repair? | -- | ||
10 | Replace the TP sensor. Refer to Throttle Position Sensor Replacement . Is the action complete? | -- | -- | |
|
Important: : Replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Is the action complete? | -- | -- | ||
12 |
Does scan tool indicate DTC P0123 failed? | -- | System OK |
