• 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.

For symptom byte information, refer to Symptom Byte List.

Lane keep assist is enabled and disabled through the lane keep assist switch, located in the S70L Steering Wheel Controls Switch - Left. The lane keep assist indicator, also located in the S70L Steering Wheel Controls Switch - Left, receives voltage from the S70R Steering Wheel Controls Switch - Right. This voltage is PWM controlled to vary the brightness level of the indicator depending on commanded interior light dimming. When lane keep assist is enabled, the B174W Frontview Camera – Windshield will illuminate the lane keep assist indicator by ground the indicator control circuit.

Ignition ON.

The B174W Frontview Camera – Windshield detects a short to voltage in the control circuit.

The B174W Frontview Camera – Windshield detects a short to ground or an open/high resistance in the control circuit.

• Lane keep assist functions are disabled
• The driver information center displays “Service Driver Assist”

The condition for setting the DTC is no longer present.

Driver Assistance Systems Schematics

Master Electrical Component List

Lane Keep Assist Description and Operation

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

Control Module References for scan tool information

1. Ignition ON.
2. Verify DTC B356A is not set.
• If the DTC is set

  Refer to DTC B356A

• If the DTC is not set
3. Verify the lane keep assist indicator turns ON and OFF while pressing and releasing the lane keep assist switch.
• If the indicator does not turn ON and OFF

  Refer to Circuit/System Testing.

• If the indictor turns ON and OFF
4. All OK.

1. Ignition OFF, disconnect the harness connector at the S70L Steering Wheel Controls Switch - Left, ignition ON.

Note: Verify interior light dimming is turned all the way up.

2. Verify a test lamp illuminates between the control circuit terminal 4 and ground.
• If the test lamp does not illuminate
1. Ignition OFF, disconnect the harness connector at the S70R Steering Wheel Controls Switch - Right.
2. Test for infinite resistance between the control circuit and ground.
• If less than infinite resistance, repair the short to ground in the circuit.
• If infinite resistance
3. Test for less than 2 Ω in the control circuit end to end.
• If 2 Ω or greater, repair the open/high resistance in the circuit.
• If less than 2 Ω, replace the S70R Steering Wheel Controls Switch - Right.
• If the test lamp illuminates
3. Ignition OFF, connect the harness connector at the S70L Steering Wheel Controls Switch - Left. Disconnect the harness connector at the B174W Frontview Camera – Windshield, ignition ON.
4. Verify the lane keep assist indicator is not illuminated.
• If the lane keep assist indicator is illuminated
1. Ignition OFF, disconnect the harness connector at the S70L Steering Wheel Controls Switch - Left.
2. Test for infinite resistance between the control circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the S70L Steering Wheel Controls Switch - Left.
• If the lane keep assist indicator is not illuminated
5. Connect a 3 A fused jumper wire between the control circuit terminal 4 and ground
6. Verify the lane keep assist indicator is illuminated.
• If the lane keep assist indicator is not illuminated
1. Ignition OFF, disconnect the harness connector at the S70L Steering Wheel Controls Switch - Left, ignition ON.
2. Test for less than 1 V between the control circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V
3. Ignition OFF.
4. Test for less than 2 Ω in the control circuit end to end.
• If 2 Ω or greater, repair the open/high resistance in the circuit.
• If less than 2 Ω, replace the S70L Steering Wheel Controls Switch - Left.
• If the lane keep assist indicator is illuminated
7. Test or replace the B174W Frontview Camera – Windshield.

Perform the Diagnostic Repair Verification after completing the repair

• Cruise Control Switch Replacement for S70L Steering Wheel Controls Switch - Left replacement
• Control Module References for B174W Frontview Camera – Windshield replacement, programming, and setup.