P0122

DTC P0122: Throttle Position Sensor (main) Circuit Low Input














CIRCUIT OPERATION

- A 5-volt power supply is applied on the throttle position sensor (main) power terminal (terminal No. 5) from the ECM (terminal No. 12).
- A voltage that is according to the throttle opening angle is sent to the ECM (terminal No. 10) from the throttle position sensor (main) output terminal (terminal No. 4).
- The ground terminal (terminal No. 3) is grounded with ECM (terminal No. 13).

TECHNICAL DESCRIPTION

- The throttle position sensor (main) outputs voltage which corresponds to the throttle valve opening angle.
- The ECM checks whether the voltage is within a specified range.

DESCRIPTIONS OF MONITOR METHODS

Throttle position sensor (main) output voltage is out of specified range.

MONITOR EXECUTION

Continuous

MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)

Other Monitor (There is no temporary DTC stored in memory for the item monitored below)

- Not applicable
Sensor (The sensor below is determined to be normal)

- Not applicable

DTC SET CONDITIONS

Logic Flow Chart






Check Condition

- Ignition switch is "ON" position.
Judgement Criterion

- Throttle position sensor (main) output voltage should be 0.2 volt or less for 0.3 second.

FAIL-SAFE AND BACKUP FUNCTION

- Throttle opening degree is restricted.
- Throttle opening degree position is in default position if throttle position sensor (sub) fails.

OBD-II DRIVE CYCLE PATTERN

None.

TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)

- Throttle position sensor failed.
- Shorted throttle position sensor (main) circuit, harness damage, or connector damage.
- ECM failed.


DIAGNOSIS

Required Special Tools:

- MB991958: Scan tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness A
- MB991658: Test Harness


STEP 1. Using scan tool MB991958, check data list item 13: Throttle Position Sensor (main).





CAUTION:
To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.

(1)Connect scan tool MB991958 to the data link connector.
(2)Turn the ignition switch to the "ON" position.
(3)Detach the intake air hose at the throttle body.
(4)Disconnect the connector of the throttle position sensor.
(5)Use test harness special tool (MB991658) to connect only terminals No. 3, No. 4, No. 5, and No. 6.
(6)Set scan tool MB991958 to the data reading mode for item 13, Throttle Position Sensor (main).

- Output voltage should be between 0.3 and 0.7 volt when the throttle valve is fully closed with your finger.
- Output voltage should be 4.0 volts or more when the throttle valve is fully open with your finger.
(7)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the sensor operating properly?

YES It can be assumed that this malfunction is intermittent. How to Cope With Intermittent Malfunctions.

NO Go to Step 2.

STEP 2. Check harness connector B-11 at throttle position sensor and harness connector B-09 at ECM for damage.

Q. Is the harness connector in good condition?

YES Go to Step 3.
NO Repair or replace it. Harness Connector Inspection.
Then go to Step 7.
STEP 3. Check for harness damage between throttle position sensor connector B-11 (terminal No. 5) and ECM connector B-09 (terminal No. 12).

Q. Is the harness wire in good condition?

YES Go to Step 4.
NO Repair it. Then go to Step 7.
STEP 4. Check for short circuit to ground and harness damage between throttle position sensor connector B-11 (terminal No. 4) and ECM connector B-09 (terminal No. 10).

Q. Is the harness wire in good condition?

YES Go to Step 5.
NO Repair it. Then go to Step 7.
STEP 5. Using scan tool MB991958, check data list item 13: Throttle Position Sensor (main).

(1)Turn the ignition switch to the "ON" position.

(2)Detach the intake air hose at the throttle body.

(3)Disconnect the connector of the throttle position sensor.

(4)Use test harness special tool (MB991658) to connect only terminals No. 3, No. 4, No. 5, and No. 6.

(5)Set scan tool MB991958 to the data reading mode for item 13, Throttle Position Sensor (main).

- Output voltage should be between 0.3 and 0.7 volt when the throttle valve is fully closed with your finger.
- Output voltage should be 4.0 volts or more when the throttle valve is fully open with your finger.

(6)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the sensor operating properly?

YES It can be assumed that this malfunction is intermittent. How to Cope With Intermittent Malfunctions.
NO Go to Step 6.
STEP 6. Replace the throttle body assembly.

(1)Replace the throttle body assembly.

(2)Turn the ignition switch to the "ON" position.

(3)After the DTC has been deleted, read the DTC again.

(4)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is DTC P0122 set?

YES Replace the ECM (Refer to, Removal and Installation Removal and Replacement).
Then go to Step 7.
NO The inspection is complete.
STEP 7. Using scan tool MB991958, read the diagnostic trouble code
(DTC).

(1)Turn the ignition switch to the "ON" position.

(2)After the DTC has been deleted, read the DTC again.

(3)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is DTC P0122 set?

YES Retry the troubleshooting.
NO The inspection is complete.