B148C
B148C-STEERING WHEEL CONTROL DOWN SWITCH CIRCUIT
For a complete wiring diagrams, refer to Wiring.
Theory of Operation
The Steering Wheel Control Down Switch, when pressed, sends a multiplexed signal to the Right Steering Switch. The switching status is transferred to the Steering Column Control Module (SCCM) by way of the LIN bus, a serial sub-bus. The SCCM converts the data to CAN(B) and sends the message to the corresponding module on the bus.
When Monitored
Continuously with the ignition on.
Set Condition
The Steering Column Control Module senses that the Steering Wheel Control Down Switch is in the Set position for greater than 50 seconds.
Possible Causes
- INTERMITTENT STEERING WHEEL CONTROL DOWN SWITCH CIRCUIT DTC
- (G106) EVIC MUX SIGNAL 1 CIRCUIT SHORT TO (G907) EVIC/NAV MUX RETURN CIRCUIT
- (G106) EVIC MUX SIGNAL 1 CIRCUIT SHORT TO GROUND
- LEFT STEERING SWITCH
- RIGHT STEERING SWITCH
- STEERING COLUMN CONTROL MODULE (SCCM)
Diagnostic Test
1. DTC STATUS IS ACTIVE
NOTE: If U1109-LOST COMMUNICATION WITH LIN STEERING WHEEL CONTROLS is set along with this DTC, diagnose the communication DTC first.
NOTE: If P0562-BATTERY VOLTAGE LOW or P0563-BATTERY VOLTAGE HIGH is set along with this DTC, diagnose the battery voltage DTC first.
Ignition on, engine not running.
With the Scan Tool, select View DTCs in the Steering Column Control Module.
Is the DTC status Active at this time?
Yes >> Go to 2
No >> Go to 7
2. (G106) EVIC MUX SIGNAL 1 CIRCUIT SHORT TO (G907) EVIC/NAV MUX RETURN CIRCUIT
Turn the ignition off.
Remove the Driver Airbag in accordance with the Service Information.
Disconnect the Left Steering Switch harness connector.
Disconnect the Right Steering Switch harness connector.
NOTE: Before proceeding, thoroughly inspect the wiring harness and connectors between the Left Steering Switch and the Right Steering Switch for a short to ground or any other circuit.
Measure the resistance between the (G106) EVIC Mux Signal 1 circuit and the (G907) EVIC/NAV Mux Return circuit.
Is the resistance below 5.0 ohms?
Yes >> Repair the (G106) EVIC Mux Signal 1 circuit for a short to the (G907) EVIC/NAV Mux Return circuit.
No >> Go to 3
3. (G106) EVIC MUX SIGNAL 1 CIRCUIT SHORT TO GROUND
NOTE: Before proceeding, thoroughly inspect the wiring harness and connectors between the Left Steering Switch and the Right Steering Switch for a short to ground or any other circuit.
Measure the resistance between the (G106) EVIC Mux Signal 1 circuit and ground.
Is the resistance below 5.0 ohms?
Yes >> Repair the (G106) EVIC Mux Signal 1 circuit for a short to ground.
No >> Go to 4
4. LEFT STEERING SWITCH
Reconnect the Left Steering Switch harness connector.
Measure the resistance between the (G106) EVIC Mux Signal 1 circuit and the (G907) EVIC/NAV Mux Return circuit at the Right Steering Switch harness connector.
Is the resistance approximately 10 K ohms (± 10%)?
Yes >> Replace the Left Steering Switch in accordance with the Service Information.
No >> Go to 5
5. RIGHT STEERING SWITCH
Replace the Right Steering Switch in accordance with the Service Information.
Reconnect the C206 (LIN Bus) connector.
Turn the ignition on.
Press and release the Down Switch several times.
With the scan tool, Clear Stored DTCs in the Steering Column Control Module.
With the scan tool, select Data Display and view the Down switch data.
While monitoring the Down switch data, press and release the Down Switch several times.
Does the Down switch data change from Set to Not Set as the switch is pressed and released?
Yes >> Test complete.
No >> Go to 6
6. STEERING COLUMN CONTROL MODULE (SCCM)
View repair.
Repair
Replace the Steering Column Control Module (SCCM) in accordance with the Service Information.
7. INTERMITTENT STEERING WHEEL CONTROL DOWN SWITCH CIRCUIT DTC
The conditions necessary to set this DTC are not present at this time.
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.
While monitoring the scan tool data relative to this circuit, wiggle test the wiring and connectors.
Look for the data to change or for the DTC to reset during the wiggle test.
Were any problems found?
Yes >> Repair as necessary.
No >> Test complete.