Diagnostic Instructions

DTC Descriptors

DTC B3647 5A: Steering Wheel Remote Control Voice Control Switch Stuck

DTC B3647 08: Steering Wheel Remote Control Voice Control Switch Circuit Resistance Range/Performance

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Left Steering Wheel Control Switch Signal	1	B3647 08, B3648 08, B3649 04, B3649 08	1	B3647 5A, B3648 5A, B3649 5A
Right Steering Wheel Control Switch Signal	1	B3644 08, B3645 08, B3646 04, B3646 08	1	B3644 5A, B3645 5A, B3646 5A
Low Reference	--	1	1	--
1. Steering Wheel Controls Inoperative

Circuit/System Description

The steering column control module (SCCM) 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 SCCM 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

B3647 5A

The SCCM detects that the voice control switch is stuck for greater than 60 seconds.

B3647 08

The SCCM detects that the voice control switch resistance is out of range.

Action Taken When the DTC Sets

The SCCM will ignore the switch command.

Conditions for Clearing the DTC

Reference Information

Schematic Reference

Steering Wheel Secondary/Configurable Control Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Steering Wheel Controls Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, observe the scan tool Left Steering Remote Control Status parameter while pressing and releasing the voice control switch. The reading should be Up-Key identifying when the switch pressed, and No Key Pressed when the switch is released.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the left steering wheel control switch.
2. Ignition OFF, test for less than 2.0 ohms between the low reference circuit terminal 2 and ground.

⇒	If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the SCCM.

3. Ignition ON, test for 4.8-5.2 volts between the signal circuit terminal 1 and ground.

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

⇒	If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the SCCM.

4. If all circuits test normal, test or replace the left steering wheel control switch.

Component Testing

1. Disconnect the harness connector at the left steering wheel control switch.
2. Connect a DMM between terminals 1 and 2 of the left steering wheel control switch.

⇒	If any of the resistance measurements for the individual switches are not within the specified resistance values, replace the left steering wheel control switch.

Function Switch	Minimum Resistance Value	Maximum Resistance Value
Scroll Wheel Up	49.7 Ohms	53.7 Ohms
Scroll Wheel Down	117.5 Ohms	121.5 Ohms
Scroll Wheel Press	217.5 Ohms	221.5 Ohms
Voice/Station Presets	397 Ohms	401 Ohms
Phone/CD Changer	756 Ohms	760 Ohms
No Switch Pressed	1855 Ohms	1859 Ohms

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.