DTC P2122, P2123, P2127, P2128, or P2138
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DTC P2122, P2123, P2127, P2128, or P2138
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DTC P2122
Accelerator Pedal Position (APP) Sensor 1 Circuit Low Voltage
DTC P2123
Accelerator Pedal Position (APP) Sensor 1 Circuit High Voltage
DTC P2127
Accelerator Pedal Position (APP) Sensor 2 Circuit Low Voltage
DTC P2128
Accelerator Pedal Position (APP) Sensor 2 Circuit High Voltage
DTC P2138
Accelerator Pedal Position (APP) Sensor 1-2 Not Plausible
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Diagnostic Fault Information
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Circuit
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Short to Ground
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High resistance
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Open
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Short to Voltage
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Signal Performance
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Accelerator Pedal Position (APP) Sensor 1 5 V Reference Circuit
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P0343, P0348, P0368, P0393, P0652, P2122
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P2122, P2138
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P0651, P2122
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P0653, P2138, P2123
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P0651, P0652, P0653, P2138
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Accelerator Pedal Position (APP) Sensor 2 5 V Reference Circuit
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P0122, P0222, P0335, P0642, P0698, P0700
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P2127, P2138
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P0697, P2127
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P0123, P0221, P0699, P2138, P2128, P0700
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P0697, P0698, P0699, P2138
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Accelerator Pedal Position (APP) Sensor 1 Signal
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P2122
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P2138
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P2122
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P2123
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P2138
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Accelerator Pedal Position (APP) Sensor 2 Signal
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P2127
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P2138
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P2127
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P2128
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P2138
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Accelerator Pedal Position (APP) Sensor 1 Low Reference
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-
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P2123, P2138
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P2123
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-
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P2138
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Accelerator Pedal Position (APP) Sensor 2 Low Reference
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-
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P2127, P2138
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P2128
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-
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P2138
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APP Sensor
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Circuit
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Short to Ground
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Open
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Short to Voltage
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Operating Conditions:
The engine is operating at idle.
Parameter Normal Range:
APP Sensor 1 0%/1 V
Parameter Normal Range:
APP Sensor 2 0%/0.5 V
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5 V Reference
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0%/0.00 Volts
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0%/0.00 Volts
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0%/4.98 V
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APP Sensor 1 Signal
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0%/0.00 Volts
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0%/0.00 Volts
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0%/4.98 V
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APP Sensor 2 Signal
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0%/0.00 Volts
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0%/0.00 Volts
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0%/4.98 V
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APP Sensor 1 Low Reference
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-
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0%/4.98 V
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-
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APP Sensor 2 Low Reference
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-
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0%/4.98 V
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-
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Circuit/System Description
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The accelerator pedal assembly contains two accelerator pedal position (APP) sensors. The APP sensors are mounted in the pedal assembly and are not serviceable. The APP sensors provide a signal voltage that changes relative to the position of the accelerator pedal. The engine control module (ECM) supplies a separate 5 V reference and low reference circuit for each of the APP sensors.
The APP sensor 1 signal voltage increases as the pedal is depressed, from approximately 1.0 V at rest to approximately 4 V when fully depressed. The APP sensor 2 signal voltage increases as the pedal is depressed, from approximately 0.5 V at rest to approximately 2 V with the accelerator pedal fully depressed.
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Conditions for Running the DTCs
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The ignition is ON or engine is running.
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The ignition voltage is greater than 7 V.
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The DTCs run continuously when the above conditions are met.
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Conditions for Setting the DTC
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P2122
The APP sensor 1 voltage is less than 0.74 V for greater than 1 second, or a cumulative of 10 s.
P2123
The APP sensor 1 voltage is greater than 4.82 V for greater than 1 second, or a cumulative of 10 s.
P2127
The APP sensor 2 voltage is less than 0.63 V for greater than 1 second, or a cumulative of 10 s.
P2128
The APP sensor 2 voltage is greater than 4.82 V for greater than 1 second, or a cumulative of 10 s.
P2138
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The ECM detects that the voltage difference between APP sensor 1 and the calculated idle range is greater than 0.25 V, with a released pedal.
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The ECM detects that the voltage difference between APP sensor 2 and the calculated idle range is greater than 0.31 V, with a released pedal.
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The ECM detects that the voltage difference between APP sensor 1 and 2 is greater than 0.31 V with a partially pressed pedal.
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The ECM detects that the voltage difference between APP sensor 1 and 2 is greater than 1.70 V with a fully pressed pedal.
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The ECM detects that the voltage difference between APP sensor 1 and 2 is greater than 0.04 V when APP sensor 1 is greater than 1.17 V.
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Any of the above conditions exist for greater than 1 second, or a cumulative of 10 s.
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Action Taken When the DTC Sets
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DTCs P2122, P2123, P2127, P2128, and P2138 are type A DTCs.
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Conditions for Clearing the DTC
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DTCs P2122, P2123, P2127, P2128, and P2138 are type A DTCs.
Test the current output of the 5 V reference circuits if you suspect high resistance in the circuit. The current output should be greater than 80 mA for APP 1 and greater than 50 mA for APP 2.
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
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Circuit/System Verification
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1.
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Ignition ON, check the diagnostic trouble code (DTC) information with a scan tool. DTC P0651, P0652, P0653, P0697, P0698 or P0699 are not set.
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3.
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Observe the scan tool APP Sensor 1 and 2 voltage parameters. Verify both of the APP sensor voltages are between 0.4-4.5 V.
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4.
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Rapidly depress the accelerator pedal from the rest position to the wide open throttle position (WOT) and release pedal. Repeat the procedure several times. DTC P2122, P2123, P2127, P2128 or P2138 are not set.
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5.
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Slowly depress the accelerator pedal to WOT and then slowly return the pedal to closed throttle. Repeat the procedure several times. DTC P2122, P2123, P2127, P2128 or P2138 are not set.
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6.
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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.
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1.
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Ignition OFF, remove the fuse that supplies B+ to terminal 56 X2 of the ECM.
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2.
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Disconnect the harness connector at the B107 Accelerator Pedal Assembly.
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3.
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Test for less than 5 Ω between the appropriate low reference circuit listed below and ground.
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B107 APP sensor 1 terminal 4
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B107 APP sensor 2 terminal 5
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4.
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If greater than the specified range, test the low reference circuit for a short to voltage, or an open/high resistance. If the circuit/connections test normal, replace the K20 Engine Control Module.
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5.
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Install fuse that supplies B+ to terminal 56 X2 of the ECM.
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6.
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Note
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The 5 V reference circuit voltage can be within the specified range with a high resistance in the circuit. If this condition is suspected, refer to Diagnostic Aids.
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Ignition ON, test for 4.8-5.2 V between the appropriate 5 V reference circuit listed below and ground.
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B107 APP sensor 1 terminal 2
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B107 APP sensor 2 terminal 1
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7.
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If less than the specified range, test the 5 V reference circuit for a short to ground or open/high resistance. If the circuit/connections test normal, replace the K20 Engine Control Module.
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8.
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If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit/connections test normal, replace the K20 Engine Control Module.
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9.
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Observe the scan tool APP sensor 1 voltage parameter. Verify the voltage is less than 0.3 V.
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10.
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If greater than the specified range, test the signal circuit terminal 3 for a short to voltage. If the circuit/connections test normal, replace the K20 Engine Control Module.
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11.
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Observe the scan tool APP sensor 2 voltage parameter. Verify the voltage is less than 0.3 V.
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12.
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If greater than the specified range, test the signal circuit terminal 6 for a short to voltage. If the circuit/connections test normal, replace the K20 Engine Control Module.
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13.
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Connect a 3 A fused jumper wire between the APP sensor 1 signal circuit terminal 3 and the 5 V reference circuit terminal 2. Verify the APP sensor 1 voltage parameter is greater than 4.8 V.
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14.
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If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit/connections test normal, replace the K20 Engine Control Module.
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15.
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Connect a 3 A fused jumper wire between the APP sensor 2 signal circuit terminal 6 and the 5 V reference circuit terminal 1. Verify the APP sensor 2 voltage parameter is greater than 4.8 V.
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16.
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If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit/connections test normal, replace the K20 Engine Control Module.
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17.
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If all circuits/connections test normal, test or replace the B107 Accelerator Pedal Assembly.
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1.
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Connect a 3 A fused jumper wire between the 5 V reference terminal of the applicable APP sensor terminal 2 or 1 and 5 V. Install a jumper wire between the applicable low reference terminal 4 or 5 and a ground.
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2.
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Sweep the sensor through the entire range while monitoring the voltage between the appropriate signal circuit terminal 3 or 6 and the low reference terminal 4 or 5 with a DMM. The voltage for APP 1 should vary between approximately 0.90-4.35 V without any spikes or dropouts. The voltage for APP 2 should vary between approximately 0.40-2.20 V without any spikes or dropouts.
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3.
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If the voltage is not within the specified range or is erratic on either APP sensor, replace the B107 Accelerator Pedal Assembly.
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Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
