DTC p2138
Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
Accelerator Pedal Position (APP) Sensor 1-2 Correlation
Diagnostic Fault Information
| Circuit | Short to Ground | Open | Short to Voltage | Signal Performance |
|---|
| APP Sensor 1 Signal | P2122 | P2122 | P2123 | P2138 |
| APP Sensor 1 5-Volt Reference | P2122 | P2122 | P2123 | -- |
| APP Sensor 1 Low Reference | -- | P2123 | -- | -- |
| APP Sensor 2 Signal | P2127 | P2128 | P2128 | P2138 |
| APP Sensor 2 5-Volt Reference | P2127 | P2127 | P2128 | -- |
| APP Sensor 2 Low Reference | -- | P2128 | -- | -- |
Typical Scan Tool Data
App Sensor 1
| Circuit | Short to Ground | Open | Short to Voltage |
|---|
| Parameter Normal Range: 0.13-4.87 V |
| APP Sensor 1 Signal | 0 V | 0 V | 5 V |
| APP Sensor 1 5-Volt Reference | 0 V | 0 V | 5 V |
| APP Sensor 1 Low Reference | -- | 5 V | -- |
App Sensor 2
| Circuit | Short to Ground | Open | Short to Voltage |
|---|
| Parameter Normal Range: 0.13-4.87 V |
| APP Sensor 2 Signal | 0 V | 0 V | 5 V |
| APP Sensor 2 5-Volt Reference | 0 V | 0 V | 5 V |
| APP Sensor 2 Low Reference | -- | 5 V | -- |
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 |
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. |
| • | The accelerator pedal is not in the rest position. |
| • | DTC P2138 runs continuously when the above conditions are met. |
Conditions for Setting the DTC
The voltage difference between APP sensor 1 and APP sensor 2 exceeds a predetermined value for more than 2 seconds.
Action Taken When the DTC Sets
| • | DTC P2138 is a Type A DTC. |
| • | 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
DTC P2138 is a Type A DTC.
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 (Except Opel Gt)
| • | Testing for Intermittent Conditions and Poor Connections |
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/system Verification
- 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.
- Ignition ON, observe the scan tool APP sensor 2 voltage parameter. The reading should be between 0.66-4.82 volts and change with accelerator pedal input.
- Ignition ON, observe the scan tool APP Sensor 1 and 2 parameter. The scan tool should indicate agree.
- 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.
- Verify that DTCs P0641, P0642, P0643, P0651, P0652, P0653, P0697, P0698 or P0699 are set:
Circuit/system Testing
- Ignition OFF, disconnect the accelerator pedal harness connector at the accelerator pedal. Allow sufficient time for the ECM to power down.
- Test for less than 3 ohms between each low reference circuit terminals 4 and 5 and ground.
- Ignition ON, test for 4.8-5.2 volts between each 5-volt reference circuit terminals 1 and 2 and ground.
- Ignition ON, verify the scan tool APP sensor 1 and 2 voltages are less than 0.1 volt.
- 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.
- Install a 3A fused jumper wire between the signal circuit terminal 6 and the 5-volt reference circuit terminal 1 of the APP sensor 2, and verify that the APP sensor 2 voltage is greater than 4.8 volts.
- Ignition OFF, disconnect the harness connector at the ECM.
- Test for less than 5 ohms on all APP sensor circuits between the following terminals:
- Test for infinite resistance between APP sensor 1 signal circuit terminal 3 and APP sensor 2 signal circuit terminal 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
- 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.
- 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 0.66-4.82 volts with out any spikes or dropouts.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Accelerator Pedal Position Sensor Replacement |
| • | Control Module References |
