P0123

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 Setting the DTC
^ The ignition is on.
^ TP sensor signal voltage is greater than 4.88 volts for more than 9.5 seconds

Action Taken When the DTC Sets
^ The PCM will illuminate the Malfunction Indicator Lamp (MIL) during the first trip in which the diagnostic runs and fails.
^ If equipped with traction control, the PCM will command the EBTCM via the serial data circuit to turn OFF traction control and illuminate the TRACTION OFF lamp.
^ 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.

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.
^ 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 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. Symptom Related Diagnostic Procedures

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:
9. Components that share the TP sensor 5 volt reference A circuit include the following devices:
^ The EGR valve
^ The engine oil pressure sensor
^ The 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.
13. 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.