P2128-ACCELERATOR PEDAL POSITION SENSOR 2 CIRCUIT HIGH

For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The Accelerator Pedal Position (APP) Sensor contains two independent three wire sensors. Each sensor provides independent pedal position signals to the Powertrain Control Module (PCM). The raw voltage signal from APP Sensor 1 is twice the raw voltage signal from APP Sensor 2. Although the raw voltage signals differ, the scan tool converts and displays these voltages as matching percentages of pedal travel.

When Monitored:
With the ignition on.
Set Condition:
The APP Sensor 2 signal circuit is above 2.5 volts for 0.31 seconds.

Possible Causes
(K856) APP SENSOR 2 5-VOLT SUPPLY CIRCUIT SHORTED TO VOLTAGE
(K29) APP SENSOR 2 SIGNAL CIRCUIT SHORTED TO VOLTAGE
(K29) APP SENSOR 2 SIGNAL CIRCUIT SHORTED TO THE (K856) APP SENSOR 2 5-VOLT SUPPLY CIRCUIT OR (K855) APP SENSOR 1 5-VOLT SUPPLY CIRCUIT
(K400) APP SENSOR 2 SENSOR GROUND CIRCUIT OPEN/HIGH RESISTANCE
ACCELERATOR PEDAL POSITION SENSOR
POWERTRAIN CONTROL MODULE (PCM)

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

1. DTC IS ACTIVE

NOTE: If any Sensor Reference or Sensor Supply voltage DTCs are present, perform the applicable diagnostic procedure before continuing with this test.

NOTE: The APP Sensor 2 signal should always be approximately half the voltage of the APP Sensor 1 signal.

1.	Ignition on, engine not running.

2.	With the scan tool, erase DTCs in the PCM.

3.	Fully depress and release the Accelerator Pedal several times.

4.	With the scan tool, select View DTCs.

Is the status Active for this DTC?

Yes

Go To 2

Perform the INTERMITTENT DTC diagnostic procedure. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

2. CHECK THE (K29) APP SENSOR 2 SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE

1.	Disconnect the PCM C2 harness connector.

2.	Remove the ASD Relay from the TIPM.

3.	Connect a jumper wire between cavity 30 and cavity 87 of the ASD Relay connector.

4.	Turn the ignition on.

5.	Measure the voltage of the (K29) APP Sensor 2 Signal circuit in the APP Sensor harness connector.

Is there voltage present on any of the circuits?

Yes

Repair the (K29) APP Sensor 2 Signal circuit for a short to voltage.
Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

Go To 3

3. CHECK THE (K29) APP SENSOR 2 SIGNAL CIRCUIT FOR A SHORT TO THE 5-VOLT SUPPLY CIRCUITS

1.	Turn the ignition off.

2.	Remove the jumper wire and install the ASD Relay.

3.	Measure the resistance between the (K29) APP Sensor 2 Signal circuit and the (K856) APP Sensor 2 5-Volt Supply circuit in the APP Sensor harness connector.

4.	Measure the resistance between the (K29) APP Sensor 2 Signal circuit and the (K855) APP Sensor 1 5-Volt Supply circuit in the APP Sensor harness connector.

Is the resistance above 10k Ohms for both of the circuits?

Yes

Go To 4

Repair the (K29) APP Sensor 2 Signal circuit for a short to the circuit that measured below 10k Ohms.
Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

4. CHECK THE (K400) APP SENSOR 2 GROUND CIRCUIT FOR AN OPEN/HIGH RESISTANCE

1.	Measure the resistance of the (K29) APP Sensor 2 Signal circuit between the APP Sensor harness connector and the PCM C2 harness connector.

Is the resistance below 5.0 Ohms?

Yes

Go To 5

Repair the (K29) APP Sensor 2 Signal circuit for an open or high resistance.
Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

5. ACCELERATOR PEDAL POSITION SENSOR

1.	Reconnect the APP Sensor harness connector.

2.	Reconnect the PCM C2 harness connector.

3.	Turn the ignition on.

4.	With the scan tool, erase DTCs.

5.	Turn the ignition off.

6.	Disconnect the APP Sensor harness connector.

7.	Connect a jumper wire between the (K400) APP Sensor 2 Sensor Ground circuit and the (K29) APP Sensor 2 Signal circuit at the APP Sensor harness connector.

8.	Turn the ignition on.

9.	With the scan tool, select View DTCs.

NOTE: The scan tool should display an Accelerator Pedal Position Sensor 2 Low DTC as active with the jumper wire in place.

Does the scan tool display the DTC as described above?

Yes

Replace the Accelerator Pedal Position Sensor in accordance with the service information.
Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

Go To 6

6. POWERTRAIN CONTROL MODULE

1.	Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Accelerator Pedal Position Sensor and the Powertrain Control Module (PCM).

2.	Look for any chafed, pierced, pinched, or partially broken wires.

3.	Look for broken, bent, pushed out or corroded terminals.

4.	Perform any Technical Service Bulletins that may apply.

Were any problems found?

Yes

Repair as necessary.
Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

Replace the Powertrain Control Module in accordance with the service information.
Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

P2128-ACCELERATOR PEDAL POSITION SENSOR 2 CIRCUIT HIGH

P2128-ACCELERATOR PEDAL POSITION SENSOR 2 CIRCUIT HIGH

Theory of Operation

Possible Causes