P0123

DTC P0123 Throttle Position (TP) Sensor Circuit High (Signal Voltage High):

Throttle Position (TP) Sensor Circuit:

CIRCUIT DESCRIPTION
The Throttle Position (TP) sensor provides a voltage signal which changes relative to the throttle blade angle. Signal voltage will vary from about 0.5 volt at idle to about 4.0 volts at Wide Open Throttle (WOT).

The TP signal is one of the most important inputs used by the Vehicle Control Module (VCM) for fuel control and for most of the VCM control outputs.

On nonadjustable TP sensor switches, each time voltage drops below 1.25 volts and stops, the VCM assumes this value as 0 throttle angle and measures percent throttle from this point on.

DTC P0123 WILL SET WHEN
TP sensor signal voltage is greater than about 2.5 volts, MAP is less than 51 kPa (15 Hg) for a period greater than 4 seconds.

ACTION TAKEN (VCM WILL DEFAULT TO)
TP 19%.

NOTE: Tech 1 scan tool will not indicate default value.

DTC P0123 WILL CLEAR WHEN
Conditions for fault are no longer present and Tech 1 clear DTCs function is used or 50 ignition switch keycycles have passed with no further faults or ignition switch is turned "OFF" and Fuse #9 is removed for 10 seconds.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. If TP signal is greater than 1.25 volts, then the fault is present.
2. With the TP sensor disconnected, the TP signal voltage should go low if the VCM and wiring is OK.
3. Probing CKT 452 with a test light checks the 5 volt return circuit. This step isolates a faulty sensor, VCM or an open CKT 452.

DIAGNOSTIC AIDS
A Tech 1 scan tool reads throttle position in volts. Should read about 0.45 to 0.85 volt with throttle closed and ignition "ON" or at idle. Voltage should increase at a steady rate as throttle is moved toward Wide Open Throttle (WOT).

Also, some Tech 1 scan tools will read throttle angle 0.0% = closed throttle, 100% = WOT.

Scan TP sensor while depressing accelerator pedal with engine stopped and ignition "ON." Display should vary from below 1.25 volts (1250 mV) when throttle was closed, to over 4.5 volts (4500 mV) when throttle is held at Wide Open Throttle (WOT) position.

A DTC P0123 will result if CKT 452 is open or CKT 417 is shorted to voltage. Refer to Intermittents. - Intermittent Malfunctions