P2122
DTC P2122 or P2123
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview)provides an overview of each diagnostic category.
DTC Descriptors
DTC P2122
- Accelerator Pedal Position (APP) Sensor 1 Circuit Low Voltage
DTC P2123
- Accelerator Pedal Position (APP) Sensor 1 Circuit High Voltage
Diagnostic Fault Information
Typical Scan Tool Data
Circuit/System Description
The throttle actuator control (TAC) system uses two accelerator pedal position (APP) sensors to monitor the accelerator pedal position. The APP sensors 1 and 2 are located within the pedal assembly. Each sensor has the following circuits:
* A 5-volt reference circuit
* A low reference circuit
* A signal circuit
Two processors are also used to monitor the TAC system data. Both processors are located within the engine control module (ECM). Each signal circuit provides both processors with a signal voltage proportional to pedal movement. Both processors monitor each other's data to verify that the indicated APP calculation is correct.
Conditions for Running the DTC
* The system voltage is more than 7 volts.
* The ignition is in the Unlock/Accessory or Run position.
* DTC P2122 and P2123 run continuously when the above conditions are met.
Conditions for Setting the DTC
P2122
The ECM detects that the APP sensor 1 voltage is less than 0.84 volts for more than 0.4 second.
P2123
The ECM detects that the APP sensor 1 voltage is more than 4.82 volts for more than 0.4 second.
Action Taken When the DTC Sets
* DTCs P2122 and P2123 are Type A DTCs.
* The control module commands the TAC system to operate in the Reduced Engine Power mode.
* A message center or an indicator displays Reduced Engine Power.
Conditions for Clearing the MIL/DTC
DTCs P2122 and P2123 are Type A DTCs.
Reference Information
Schematic Reference
Engine Controls Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Throttle Actuator Control (TAC) System Description (Throttle Actuator Control (TAC) System Description)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Scan Tool Reference
Control Module References (Programming and Relearning)for scan tool information
Circuit/System Verification
1. Ignition ON, observe the scan tool APP sensor 1 voltage parameter. The reading should be between 0.84-4.82 volts and change with accelerator pedal input.
2. Ignition ON, observe the scan tool APP Sensor 1 and 2 parameter. The scan tool should indicate agree.
3. Clear the DTCs with the scan tool. Operate the vehicle within the Conditions for Running the DTC, or within the conditions that you observed from the Freeze Frame/Failure Records.
4. Verify that DTCs P0652 or P0653 are not set.
• If DTCs P0641, P0642, P0643, P0651, P0652, P0653, P0697, P0698 or P0699 is set, refer to DTC P0641-P0643, P0651-P0653, or P0697-P0699 (P0641).
Circuit/System Testing
1. Ignition OFF, disconnect the accelerator pedal harness connector at the accelerator pedal. Allow sufficient time for the ECM to power down.
2. Test for less than 3 ohms between low reference circuit terminal 4 and ground.
• If greater than 3 ohms, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 2 and ground.
• If less than 4.8 volts, test the 5-volt reference circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the control module.
• If greater than 5.2 volts, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the control module.
4. Ignition ON, verify the scan tool APP sensor 1 voltage is less than 0.1 volt.
• If greater than 0.1 volt, test the APP sensor 1 signal circuit terminal 3 for a short to voltage. If the circuit tests normal, replace the ECM.
5. Install a 3A fused jumper wire between the signal circuit terminal 3 and the 5-volt reference circuit terminal 2 of the APP sensor 1, and verify the APP sensor 1 voltage is greater than 4.8 volts.
• If less than 4.8 volts, test the APP sensor 1 signal circuit for an open, or short to ground. If the circuit tests normal, replace the control module.
6. If all circuits test normal, replace the accelerator pedal.
Component Testing
Important: Circuit/System Testing must be performed before proceeding with Component Testing.
Dynamic Test
1. Install a 3A fused jumper wire between the 5-volt reference terminal of the applicable APP sensor and 5 volts. Install a jumper wire between the low reference terminal and a ground.
2. Sweep the sensor through the entire range while monitoring the voltage between the signal terminal and the low reference terminal with a DMM. the voltage should vary between 0.84-4.82 volts with out any spikes or dropouts.
• If the voltage is not within the specified range or is erratic, replace the accelerator pedal assembly.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Accelerator Pedal Position Sensor Replacement (Service and Repair)
* Control Module References (Programming and Relearning)