P0122

Code P0122, Throttle Position (TP) Sensor Circuit (Signal Voltage Low):

Intake Air Temperature (IAT), Engine Coolant Temperature (ECT), Throttle Position (TP), And Trans Temperature Sensors Wiring Schematic:

CIRCUIT DESCRIPTION
The Throttle Position (TP) sensor provides a voltage signal that changes relative to throttle blade angle. Signal voltage will vary from 0.2 - 0.74 volt at idle to above 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 for most of the PCM control outputs.

DTC P0122 WILL SET WHEN:

^ Ignition "ON."
^ TP sensor signal voltage is less than 0.16 volt for 4 seconds.

ACTION TAKEN (PCM will default to):
^ If DTC P0122 is set, the PCM will not allow 4th gear, TCC or cruise control operation. The MIL (Service Engine Soon) is illuminated.

^ If CKT 417 is open or grounded when the vehicle engine is started, a high idle may result. The Tech 1 may read the following with CKT 417 open or grounded:

TP = 0.04 volt or less, RPM > 1000 in park, Desired idle = 725, IAC counts > 40, MIL (Service Engine Soon) "ON", DTC P0122 set.

^ If the intermittent is repaired without cycling the key "OFF," the Tech 1 may read the following:

TP = 0.42 volt, RPM > 1500 in park, Desired idle = 725, IAC counts > 55, MIL (Service Engine Soon) "OFF."

TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. Determines if conditions necessary to set DTC P0122 exist.
2. Simulates DTC P0123: (high voltage) If PCM recognizes the high signal voltage and sets DTC P0123, the PCM and wiring are OK.
3. Simulates a high signal voltage. Checks CKT 417 or an open.

DIAGNOSTIC AIDS
The Tech 1 displays throttle position in volts. Voltage should increase at a steady rate as throttle is moved toward WOT.

An open or short to ground in CKT 416 or 417 will result in DTC P0122.

Check for:
^ Poor connection or damaged harness - Inspect PCM harness connectors for backed out terminal "BF11" and/or "BE6", improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness.

^ Intermittent test - Monitor TP sensor voltage display while moving related connectors and wiring harness. If the failure is induced, the display will change. This may help to isolate the location of the malfunction.

^ TP sensor scaling - Observe TP sensor voltage display while depressing accelerator pedal with engine stopped and ignition "ON." Display should vary from closed throttle TP sensor voltage when throttle is closed (0.2 0.74 volt) to over 4.0 volts when throttle is held at (WOT).