Normal Operation
The Smart Junction Box (SJB) sends a voltage signal to the headlamp switch to monitor the request for autolamps and a voltage signal to the light sensor to determine the ambient light level.
When the headlamp switch is placed in the AUTOLAMPS ON position, the voltage signal is routed to ground. When the SJB detects the headlamp switch in the AUTOLAMPS ON position, the SJB monitors the light sensor input. The light sensor determines the amount of light based on the input received from the ambient lighting conditions. When the ambient level has reached a point (determined by the internal programming of the SJB), the SJB provides voltage to the headlamps, parking and license plate lamps.
The SJB also monitors the windshield wiper motor status by sending a voltage signal to the wiper/washer module. When the windshield wiper is on (except during a mist wipe or while the wipers are on to clear washer fluid during a wash condition), the wiper/washer module grounds the circuit to indicate to the SJB that the wipers are on.
| DTC Description | Fault Trigger Conditions |
|---|---|
|
An on-demand DTC that may set when the SJB detects a short to ground from the autolamps on input circuit. |
|
An on-demand DTC that sets when the SJB detects an open or short to voltage from the light sensor input circuit. |
|
A continuous and on-demand DTC that sets when the SJB detects a short to ground from the light sensor input circuit. |
|
An on-demand DTC that sets when the SJB detects a short to ground from the wipers on input circuit. |
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Light sensor
- Headlamp switch
- Wiper/washer module
- SJB