Normal Operation
The smart junction box (SJB) sends reference signals to the headlamp switch through circuits CLF18 (BU/WH), CLF19 (VT/GN), CLF23 (WH/VT) and CLS34 (GY). The SJB also sends a reference signal to the light sensor through circuit VLF14 (BU/BN). Ground for the light sensor is provided through circuit GD116 (BK/VT).
When the headlamp switch is placed in the AUTOLAMPS ON position, the voltage signal is routed to ground through circuit GD116 (BK/VT). The light sensor determines the amount of light based on the input received from the ambient sky conditions. When the ambient level has reached a point (determined by the internal programming of the SJB), the SJB provides voltage to the exterior lamps.
| DTC Description | Fault Trigger Conditions |
|---|---|
| B1472 - Lamp Headlamp Input Circuit Short to Ground | An on-demand DTC that sets when the SJB detects the headlamps on input circuit is short to ground. |
| B1578 - Lamp Park Input Circuit Short To Ground | An on-demand DTC that sets when the SJB detects a short to ground in the parking lamps on input circuit. |
| B1692 - Autolamp Delay Circuit Short To Ground | An on-demand code that sets when the SJB detects a short to ground in the AUTOLAMPS on input circuit. |
| B1791 - Autolamp Sensor Input Circuit Open | A continuous code that sets when the SJB detects an open on the light sensor input circuit. |
| B2498 - Headlamp Switch Multiple Signals Input Active | A continuous DTC that sets when the SJB detects no inputs from the headlamp switch or multiple headlamp switch requests at the same time. |
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Light sensor
- Headlamp switch
- SJB