DTC P2127: Accelerator Pedal Position Sensor (sub) Circuit Low Input

CIRCUIT OPERATION

A 5-volt power supply is applied on the accelerator pedal position sensor (sub) power terminal (terminal No. 4) from the ECM (terminal No. 78).
A voltage that is according to the accelerator opening angle is sent to the ECM (terminal No. 77) from the accelerator pedal position sensor (sub) output terminal (terminal No. 6).
The ground terminal (terminal No. 5) is grounded with ECM (terminal No. 79).

TECHNICAL DESCRIPTION

The accelerator pedal position sensor (sub) outputs voltage which corresponds to the accelerator pedal depression.
The ECM checks whether the voltage is within a specified range.

DESCRIPTIONS OF MONITOR METHODS

MONITOR EXECUTION

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

Accelerator pedal position sensor (sub) output voltage is 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 accelerator pedal position sensor (main) fails.

OBD-II DRIVE CYCLE PATTERN

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

Accelerator pedal position sensor failed.
Open or shorted accelerator pedal position sensor (sub) 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

STEP 1. Using scan tool MB991958, check data list item 12: Accelerator Pedal Position Sensor (sub).

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 12, Accelerator Pedal Position Sensor (sub).

Output voltage is between 0.4 and 0.6 volt when foot is released from accelerator pedal.
Output voltage is 2.0 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?

It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions

Go to Step 2.

STEP 2. Check harness connector C-01 at accelerator pedal position sensor for damage.

Q. Is the harness connector in good condition?

	Go to Step 3.

	Repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then go to Step 11.

STEP 3. Measure the sensor supply voltage at accelerator pedal position sensor harness side connector C-01.

(1)Disconnect the connector C-01 and measure at the harness side.

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

(3)Measure the voltage between terminal No. 4 and ground.

Voltage should be between 4.9 and 5.1 volts.

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

Q. Is the measured voltage between 4.9 and 5.1 volts?

Go to Step 7.

Go to Step 4.

STEP 4. Check harness connector B-10 at ECM for damage.

Q. Is the harness connector in good condition?

	Go to Step 5.

	Repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then go to Step 11.

STEP 5. Check for open circuit and short circuit to ground between accelerator pedal position sensor connector C-01 (terminal No. 4) and ECM connector B-10 (terminal No. 78).

Q. Is the harness wire in good condition?

	Go to Step 6.

	Repair it. Then go to Step 11.

STEP 6. Using scan tool MB991958, check data list item 12: Accelerator Pedal Position Sensor (sub).

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

(2)Set scan tool MB991958 to the data reading mode for item 12, Accelerator Pedal Position Sensor (sub).

Output voltage is between 0.4 and 0.6 volt when foot is released from accelerator pedal.
Output voltage is 2.0 volts or higher when accelerator pedal is fully depressed.

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

Q. Is the sensor operating properly?

	It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions .

	Replace the ECM. When the ECM is replaced, register the ID code. Refer to GROUP 42B, ID Code Registration Necessity Judgment Table <Vehicles with KOS> or GROUP 42C, ID Codes Registration Judgment Table <Vehicles with WCM> . Then go to Step 11.

STEP 7. Check harness connector B-10 at ECM for damage.

Q. Is the harness connector in good condition?

	Go to Step 8.

	Repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then go to Step 11.

STEP 8. Check for harness damage between accelerator pedal position sensor connector C-01 (terminal No. 4) and ECM connector B-10 (terminal No. 78).

Q. Is the harness wire in good condition?

	Go to Step 9.

	Repair it. Then go to Step 11.

STEP 9. Check for open circuit, short circuit to ground and harness damage between accelerator pedal position sensor connector C-01 (terminal No. 6) and ECM connector B-10 (terminal No. 77)

Q. Is the harness wire in good condition?

	Go to Step 10.

	Repair it. Then go to Step 11.

STEP 10. Replace the accelerator pedal position sensor.

(1)Replace the accelerator pedal position sensor.

(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 P2127 set?

	Replace the ECM. When the ECM is replaced, register the ID code. Refer to GROUP 42B, ID Code Registration Necessity Judgment Table <Vehicles with KOS> or GROUP 42C, ID Codes Registration Judgment Table <Vehicles with WCM> . Then go to Step 11.

	The inspection is complete.

STEP 11. 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 P2127 set?

	Retry the troubleshooting.

	The inspection is complete.