Diagnostic Instructions

DTC Descriptor

DTC P2120 00: Accelerator Pedal Position (APP) Sensor 1 Circuit

DTC P2122 00: Accelerator Pedal Position (APP) Sensor 1 Circuit Low Voltage

DTC P2123 00: Accelerator Pedal Position (APP) Sensor 1 Circuit High Voltage

DTC P2125 00: Accelerator Pedal Position (APP) Sensor 2 Circuit

DTC P2127 00: Accelerator Pedal Position (APP) Sensor 2 Circuit Low Voltage

DTC P2128 00: Accelerator Pedal Position (APP) Sensor 2 Circuit High Voltage

DTC P2138 00: Accelerator Pedal Position (APP) Sensors 1-2 Not Plausible

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Accelerator Pedal Position (APP) Sensor 1 5-Volt Reference Circuit	P06A3 00, P2122 00	P2122 00, P2128 00	P06A3 00, P2135 00	P2138 00
Accelerator Pedal Position (APP) Sensor 1 Signal	P2122 00	P2122 00, P2138 00	P06A3 00, P2123 00	P2138 00
Accelerator Pedal Position (APP) Sensor 1 Low Reference	--	P2123 00, P2138 00	--	P2138 00
Accelerator Pedal Position (APP) Sensor 2 5-Volt Reference Circuit	P0107 00, P0697 00	P2127 00, P2138 00	P0106 00, P0108 00, P0697 00	P2138 00
Accelerator Pedal Position (APP) Sensor 1 Signal	P2122 00	P2122 00, P2138 00	P06A3 00, P2123 00	P2138 00
Accelerator Pedal Position (APP) Sensor 2 Low Reference	--	P2128 00, P2138 00	--	P2138 00

Typical Scan Tool Data

APP Sensor 1 and 2

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: The engine is operating at idle Parameter Normal Range: APP Sensor 1 0.88-1.08 V Parameter Normal Range: APP Sensor 2 0.39-0.59 V
APP Sensor 1 5-V Reference	0.00 V	0.00 V	2.75 V
APP Sensor 1 Signal	0.00 V	0.00 V	4.98 V
APP Sensor 1 Low Reference	--	4.96 V	--
APP Sensor 2 5-V Reference	0.00 V	0.00 V	1.35 V
APP Sensor 2 Signal	0.00 V	0.00 V	4.98 V
APP Sensor 2 Low Reference	--	4.92 V	--

Circuit/System Description

The accelerator pedal assembly contains 2 accelerator pedal position (APP) sensors. The APP sensors are mounted to the accelerator pedal assembly and are not serviceable. The APP sensors provide a signal voltage that changes relative to pedal position. The engine control module (ECM) supplies each APP sensor with a 5-volt reference circuit, a low reference circuit, and a signal circuit.

Both the APP sensors 1 and 2 signal percentages increase as the pedal is depressed, from approximately 0% at rest to above 95% when fully depressed.

Conditions for Running the DTC

P2120 00, P2122 00, P2123 00, P2125 00, P2127 00, P2128 00

P2138 00

Conditions for Setting the DTC

P2120 00

The ECM detects that APP sensor 1 voltage is less than 0.59 V for greater than 0.4 s.

P2122 00

The ECM detects that the APP sensor 1 voltage is less than 0.46 V for less than 1 s.

P2123 00

The ECM detects that the APP sensor 1 voltage is greater than 4.7 V for less than 1 s.

P2125 00

The ECM detects that the APP Sensor 2 voltage is less than 0.5 V for less than 1 s.

or

The ECM detects that the APP Sensor 2 voltage is greater than 4.8 V for less than 1 s.

P2127 00

The ECM detects that the APP sensor 2 voltage is less than 0.32 V for less than 1 s.

P2128 00

The ECM detects that APP sensor 2 voltage is greater than 2.64 V for greater than 0.5 s.

P2138 00

The ECM detects that APP sensor 1 and APP sensor 2 disagree greater than 10% for less than 1 s.

or

The ECM detects that both APP sensor 1 and APP sensor 2 are 5% greater than the learned minimum position for less than 1 s.

Action Taken When the DTC Sets

Conditions for Clearing the DTC

Diagnostic Aids

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Throttle Actuator Control (TAC) System Description

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON, observe the DTC information with a scan tool. Verify DTCs P0697 00 or P06A3 00 are not set.

⇒	If a DTC is set, refer to DTC P0641, P0651, P0697, or P06A3.

2. Ignition ON, observe the scan tool APP Sensor 1 and 2 Indicated parameters. Both parameters should be 0%.
3. Observe the scan tool APP Sensor 1 and 2 Agree/Disagree parameter while performing the following tests:

•	Rapidly depress the accelerator pedal from the rest position to the wide open throttle position (WOT) and release pedal. Repeat the procedure several times.

•	Slowly depress the accelerator pedal to WOT and then slowly return the pedal to closed throttle. Repeat the procedure several times.

⇒	The APP sensor 1 and 2 Agree/Disagree parameter should display Agree.

4. Observe the DTC information with a scan tool. DTCs P2120 00, P2122 00, P2123 00, P2127 00, P2128 00, or P2138 00 should not set.
5. Operate the vehicle within the conditions for running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the freeze frame / failure records data.

Circuit/System Testing

1. Ignition OFF, disconnect the B107 Accelerator Pedal Position Sensor harness connector at the accelerator pedal assembly.
2. Ignition OFF for 1 min, test for less than 5 Ω between the low reference circuit terminals listed below and ground.

•	Low reference circuit terminal 4

•	Low reference circuit terminal 5

⇒	If greater than the specified range, test the appropriate low reference circuit for a short to voltage, or an open / high resistance. If the circuit tests normal, replace the K20 Engine Control Module.

3. Ignition ON, test for 4.8-5.2 V between both 5-volt reference circuit terminals listed below and ground.

•	5 V reference circuit terminal 1

•	5 V reference circuit terminal 2

⇒	If less than the specified range, test the appropriate 5-volt reference circuit for a short to ground or open / high resistance. If the circuit tests normal, replace the K20 Engine Control Module.

⇒	If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module.

4. Verify the appropriate APP sensor voltage parameter is at 0 V.

⇒	If greater than the specified range, test the appropriate signal circuit terminal listed below for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module.

•	APP sensor 1 signal circuit terminal 3

•	APP sensor 2 signal circuit terminal 6

5. Install a 3A fused jumper wire between the appropriate signal circuit terminal listed below and the 5-volt reference circuit terminal 1 of the appropriate B107 Accelerator Pedal Position Sensor. Verify the appropriate APP Sensor voltage parameter is greater than 4.8 V.

•	APP sensor 1 signal circuit terminal 3

•	APP sensor 2 signal circuit terminal 1

⇒	If less than the specified range, test the appropriate signal circuit for a short to ground or an open / high resistance. If the circuit tests normal, replace the K20 Engine Control Module.

6. If all circuits test normal, replace the accelerator pedal assembly.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.