Diagnostic Instructions

DTC Descriptors

DTC B1529 03: Device Voltage Reference Output Circuit Voltage Below Threshold

DTC B1529 07: Device Voltage Reference Output Circuit Voltage Above Threshold

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

B1529 03

The BCM senses the supply voltage circuit is below 1.0 volt after 5 seconds

B1529 07

The BCM senses the supply voltage circuit above 24.5 volts after 5 seconds.

Action Taken When the DTC Sets

The BCM will ignore the switch command.

Conditions for Clearing the DTC

Diagnostic Aids

Reference Information

Schematic Reference

Steering Wheel Secondary/Configurable Control Schematics

Connector End View Reference

Description and Operation

Steering Wheel Controls Description and Operation

Electrical Information Reference

Scan Tool Reference

Circuit/System Verification

1. Verify DTC B1529 07 is not set.

⇒	If the DTC is set, clear the DTC and operate the vehicle within the Conditions for Running the DTC. If the DTC resets, refer to Charging System Test.

2. Ignition ON, observe the scan tool SWC Bank 1 status while pressing and releasing the switches. The reading should be SW1-SW7 identifying the switch pressed, and Idle when released.

Circuit/System Testing

Important: It is recommended that component testing is performed before circuit testing when diagnosing steering wheel controls.

Caution: Refer to SIR Caution in the Preface section.

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 3 and ground.

⇒	If less than specified value, test the ignition circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the BCM.

3. Test for the 0 volts between the signal circuit terminal 4 and ground.

⇒	If greater than specified value, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM.

4. Test for ignition voltage between the ignition circuit terminal 3 and the signal circuit terminal 4.

⇒	If less than specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the BCM.

5. Ignition OFF, disconnect the X1 harness connector at the BCM.
6. Test for infinite resistance between the signal circuit terminal 6 and ground.

⇒	If less than specified value, test the signal circuit for a short to ground.

7. If all circuits test normal, test or replace switch.

Component Testing

Caution: Refer to SIR Caution in the Preface section.

1. Ignition OFF, disconnect the harness connector at the suspect steering wheel control switch.
2. Test for infinite resistance between the ignition terminal 3 and the signal terminal 4 with the switch in the open position.

⇒	If less than specified value, replace the switch.

3. Test for less than 5,400 ohms of resistance between the signal terminal 4 and the ignition terminal 3 with the switch in the closed position.

⇒	If greater than the specified value, replace the steering wheel control switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.