P0121

C : DTC P0121, P0122, P0123

C1 : CHECK THE POWER SUPPLY TO THE THROTTLE POSITION SENSOR
1. Turn the ignition switch the to the RUN position.
2. Measure the voltage between the throttle position sensor electrical connector PI 26 pin 4 (OY) and ground.

Is the voltage less than 4.5 volts?

Yes
Goto C2

No
Goto C4

C2 : CHECK THE THROTTLE POSITION SENSOR POWER SUPPLY CIRCUIT FOR OPEN CIRCUIT
1. Turn the ignition switch to the OFF position.
2. Disconnect the PCM electrical connector PI 1 and the throttle position sensor electrical connector PI 26.
3. Measure the resistance between PI 1 pin 12 (OY) and PI 26 pin 4 (OY).

Is the resistance less than 5 ohms?

Yes
Goto C3

No
REPAIR the throttle position sensor power supply circuit from the PCM to the throttle position sensor. CLEAR the DTC. TEST the system for normal operation.

C3 : CHECK THE THROTTLE POSITION SENSOR POWER SUPPLY CIRCUIT FOR A SHORT TO GROUND
1. Measure the resistance between PI 26-pin 4 (OY) and ground.
Is the resistance greater than 10,000 ohms?

Yes
DIAGNOSE the electronic engine control system. Electronic Engine Controls

No
REPAIR the throttle position sensor power supply circuit from the PCM to the throttle position sensor. CLEAR the DTC. TEST the system for normal operation.

C4 : CHECK THE THROTTLE POSITION SENSOR GROUND CIRCUIT
1. Turn the ignition switch to the OFF position.
2. Disconnect the throttle position sensor electrical connector PI 26.
3. Measure the resistance between PI 26 pin 1 (BG) and ground.

Is the resistance less than 5 ohms?

Yes
Goto C6

No
Goto C5

C5 : CHECK THE THROTTLE POSITION SENSOR GROUND WIRE FOR OPEN CIRCUIT
1. Disconnect the PCM electrical connector PI I and the throttle position sensor electrical connector PI 26.
2. Measure the resistance between PI 26 pin 1 (BG) and PI 1 pin 19 (BG).

Is the resistance less than 5 ohms?

Yes
Goto C6

No
REPAIR the throttle position sensor ground circuit from the PCM to the throttle position sensor. CLEAR the DTC. TEST the system for normal operation.

C6 : CHECK THE THROTTLE POSITION SENSOR
1. Measure the resistance between PI 26 pin 2 and PI 26 pin 4.
2. Measure the resistance between PI 26 pin 3 and PI 26 pin 4.

Are the resistor values the same?

Yes
Goto C7

No
Install a new throttle body.

C7 : CHECK CONTINUITY OF THE THROTTLE POSITION SENSOR OUTPUT CIRCUIT
1. Measure the resistance between PI 1 pin 75 (R) and PI 26 pin 3 (R).
2. Measure the resistance between PI 1 pin 76 (Y) and PI 26 pin 2 (Y).

Is the resistance less than 5 ohms?

Yes
Goto C8

No
Repair the circuit from the PCM to the throttle position sensor. CLEAR the DTC. TEST the system for normal operation.

C8 : CHECK THE THROTTLE POSITION SENSOR OUTPUT CIRCUIT FOR A SHORT TO GROUND
1. Measure the resistance between PI 26 pin 3 (R) and ground.
2. Measure the resistance between PI 26 pin 2 (Y) and ground.

Is the resistance greater than 10,000 ohms?

Yes
DIAGNOSE the electronic engine control system. Electronic Engine Controls

No
Repair the circuit from the PCM to the throttle position sensor. CLEAR the DTC. TEST the system for normal operation.