P2123
DTC P2123: Accelerator Pedal Position Sensor (main) Circuit High InputAccelerator Pedal Position Sensor (main) Circuit:
CIRCUIT OPERATION
- A 5-volt power supply is applied on the accelerator pedal position sensor (main) power terminal (terminal No. 2) from the ECM
- When the accelerator pedal is moved from the idle position to the fully opened position, the resistance between the accelerator pedal position sensor (main) output terminal (terminal No. 3) and ground terminal will increase according to the rotation.
TECHNICAL DESCRIPTION
- The accelerator pedal position sensor (main) outputs voltage which corresponds to the accelerator pedal depression.
- The ECM
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:
Logic Flow Chart
Check Conditions
- Ignition switch is "ON" position.
- Accelerator pedal position sensor (sub) output voltage is between 0.2 and 2.5 volts.
Judgement Criterion
- Accelerator pedal position sensor (main) output voltage should be 4.5 volts or higher for 1 second.
OBD-II DRIVE CYCLE PATTERN
None.
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Accelerator pedal position sensor failed or maladjusted.
- Open or shorted accelerator pedal position sensor (main) circuit, or loose connector.
- ECM failed.
- PCM failed.
DIAGNOSIS
Required Special Tools:
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991911: Main Harness B
STEP 1. Using scan tool MB991958, check data list item 78: Accelerator Pedal 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. Set scan tool MB991958 to the data reading mode for item 78, Accelerator Pedal Position Sensor (main).
- Output voltage is between 0.335 and 0.935 volts when foot is released from accelerator pedal.
- Output voltage is 4.0 volts or higher when accelerator pedal is fully depressed.
4. 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.
NO: Go to Step 2.
STEP 2. Check harness connector B-126 at accelerator pedal position sensor for damage.
Q: Is the harness connector in good condition?
YES: Go to Step 3.
NO: Repair or replace it. Then go to Step 8.
STEP 3. Check the accelerator pedal position sensor.
1. Disconnect the accelerator pedal position sensor connector B-126.
2. Measure resistance between terminal No. 1 and No. 2 and between terminal No. 7 and No. 8.
Standard value: 3.5 - 6.5 kohm
3. Measure resistance between terminal No. 2 and No. 3 and between terminal No. 6 and No. 8 when the accelerator pedal is gently depressed from idle position to the full open position.
- Resistance value changes in accordance with the accelerator pedal depression smoothly.
Q: Is the measured resistance normal?
YES: Go to Step 4.
NO: Replace the accelerator pedal position sensor.Then go to Step 8.
STEP 4. Check the continuity at accelerator pedal position sensor harness side connector B-126.
1. Disconnect the connector B-126 and measure at the harness side.
2. Measure the continuity between terminal No. 1 and ground.
- Should be less than 2 Ohms.
Q: Does continuity exist?
YES: Go to Step 7.
NO: Go to Step 5.
STEP 5. Check harness connector C-139 at ECM
Q: Is the harness connector in good condition?
YES: Go to Step 6.
NO: Repair or replace it. Then go to Step 8.
STEP 6. Check for open circuit and harness damage between accelerator pedal position sensor connector B- 126 (terminal No. 1) and ECM connector C-139
Q: Is the harness wire in good condition?
YES: Go to Step 7.
NO: Repair it. Then go to Step 8.
STEP 7. Using scan tool MB991958, check data list item 78: Accelerator Pedal 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. Set scan tool MB991958 to the data reading mode for item 78, Accelerator Pedal Position Sensor (main).
- Output voltage is between 0.335 and 0.935 volts when foot is released from accelerator pedal.
- Output voltage is 4.0 volts or higher when accelerator pedal is fully depressed.
4. 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.
NO: Replace the ECM or the PCM. Then go to Step 8.
STEP 8. Using scan tool MB991958, read the diagnostic trouble code (DTC).
1. Connect scan tool MB991958 to the data link connector.
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 P2123 set?
YES: Retry the troubleshooting.
NO: The inspection is complete.