B1397
DTC B1397 or B2815
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC B2815
- Steering Wheel Controls Illegal Resistance Value
DTC B1397
- Device Voltage Reference Output Circuit Low
Diagnostic Fault Information
Circuit/System Description
The body control module (BCM) supplies voltage to the audio steering wheel control multiple momentary contact switches and monitors the return signal. Each switch is associated to a set resistance value, when pressed a specific voltage drop occurs through a series of resistors unique to that switch. The BCM identifies the selection, then sends a serial data message that is received by the component controlled, activating the feature.
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
DTC B2815
The BCM senses a switch voltage that is higher than normal.
DTC B1397
The BCM senses a short to ground in the voltage circuit for more than 1 second.
Action Taken When the DTC Sets
The BCM will ignore the switch command.
Conditions for Clearing the DTC
* A current DTC clears when the malfunction is no longer present.
* A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.
Diagnostic Aids
* This diagnostic is for the audio steering wheel controls.
* Before diagnosis of the steering wheel controls, ensure the primary controls of the associated component are functioning properly.
Circuit/System Verification
Ignition ON, observe the scan tool Steering Wheel Controls (SWC) Switch Voltage parameter. Pressing the switch should read voltage present, and drop to 0 volts when released.
Circuit/System Testing
Important: It is recommended that Component Testing be performed before Circuit Testing when diagnosing steering wheel controls.
Caution: Refer to SIR Caution.
1. Ignition OFF, disconnect the harness connector at the right steering wheel control switch.
2. Ignition ON, test for ignition voltage between the ignition circuit terminal 1 and ground.
• If less than the specified value, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
• If greater than the specified value, test the ignition circuit for a short to voltage. If the circuit tests normal, replace the BCM.
3. Test for ignition voltage between the ignition circuit terminal 1 and the signal circuit terminal 6.
• If less than the specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the BCM.
• If greater than the specified value, test the signal circuit for a short to voltage.
4. Install a 3A fused jumper wire between the ignition circuit terminal 1 and the signal circuit terminal 2.
5. Disconnect the harness connector at the left steering wheel control switch.
6. Test for ignition voltage between the signal circuit terminal 1 and ground.
• If less than the specified value, test the signal circuit for a short to ground, or an open/high resistance. If the circuit tests normal, replace the BCM.
• If greater than the specified value, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM.
7. Test for ignition voltage between the between the signal circuit terminal 1 and the signal circuit terminal 5.
• If less than the specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the BCM.
• If greater than the specified value, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM.
8. Ignition OFF, disconnect the C3 harness connector at the BCM.
9. Test for infinite resistance between the signal circuit terminal A2 and ground.
• If less than the specified value, test the signal circuit for a short to ground. If the circuit tests normal, replace the BCM.
10. If all circuits test normal, test or replace the switch.
Component Testing
Caution: Refer to SIR Caution.
1. Ignition OFF, disconnect the harness connector at the right steering wheel control switch.
2. Test the for less than 2,400 ohms between the ignition terminal 1 and the signal terminal 2.
• If greater than the specified range, replace the steering wheel control switch.
3. Test for infinite resistance between the ignition terminal 1 and the signal terminal 6 with the switch in the open position.
• If not the specified value, replace the steering wheel control switch.
4. Test the for less than 2,400 ohms between the ignition terminal 1 and the signal terminal 6 with the switch in the closed position.
• If greater than the specified range, replace the right steering wheel control switch.
5. Disconnect the harness connector at the left steering wheel control switch.
6. Test for infinite resistance between the signal terminal 1 and the signal terminal 5 with the switch in the open position.
• If not the specified value, replace the steering wheel control switch.
7. Test for less than 12,000 ohms between the signal terminal 1 and the signal terminal 5 with the switch in the closed position.
• If greater than the specified range, replace the steering wheel control switch.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
* Steering Wheel Control Switch Assembly Replacement
* Control Module References for BCM replacement, setup, and programming Programming and Relearning Verification Tests