P0123

Diagnostic Chart (Part 1 Of 2):

Diagnostic Chart (Part 2 Of 2):

Schematic:

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

CONDITIONS FOR RUNNING THE DTC
The engine is running.

CONDITIONS FOR SETTING THE DTC
^ TP sensor signal voltage is more than 4.9 volts.
^ Above conditions are present for more than 1 second.

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.
^ If the misfire is determined to be catalyst damaging, the PCM will flash the MIL.

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 a scan tool.

DIAGNOSTIC AIDS
Check for the following conditions:
^ Poor connection at 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 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 malfunction.
^ Malfunctioning 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 the DTC cannot be duplicated and is determined to be intermittent, reviewing the Failure Records can be useful in determining when the DTC was last set. Also refer to Testing for Intermittent and Poor Connections in Diagrams.

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 fuel tank 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.