P0123

Diagnostic Chart:

Diagnostic Chart (cont'd):

Wiring Diagram:

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 P0123 will set when the PCM detects an excessively high signal voltage on the throttle position sensor signal circuit.


CONDITIONS FOR SETTING THE DTC

- The ignition is ON.

- TP sensor signal voltage is greater than 4.71 volts.

- 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 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 fault.

- The DTC can be cleared by using the scan tool Clear Info function or by disconnecting the PCM battery feed.


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 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.

- Faulty TP sensor: With the key ON, engine not running, observe the TP sensor display on the scan tool while slowly depressing the accelerator to wide open throttle. If a voltage over 4.71 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 Diagnostic Chart may isolate the cause of the fault.

TEST DESCRIPTION

Number(s) below refer to the Step number(s) on the Diagnostic Table:

8. Components that share the TP sensor 5 volt reference A circuit include the following devices:

- EGR valve

- MAP sensor

Disconnect these components one at a time while observing the TP sensor display on the scan tool. If the reading changes drastically when one of these components is disconnected, replace the component that affected the reading.

12. This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.