• | 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. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
CHMSL/BCK/UP Fuse B+ | 1 | 1 | -- | -- |
I/P Dimming 10-Volt Reference | B2610 | B2610 | 1 | -- |
Instrument Panel Lamps Dimmer Switch Signal | C0870 | 1 | 1 | -- |
Instrument Panel Lamp Control | 1 | 1 | 1 | -- |
Headlamp Switch Ground | -- | 1 | -- | -- |
1. Interior Backlighting Malfunction |
The body control module (BCM) is responsible for the dimming of the interior lights. The BCM receives a varying signal from the I/P dimmer switch. Based on the position of the I/P dimmer switch, the BCM then supplies the appropriate amount of voltage to the interior lamps. When the headlight switch is turned to the PARK or HEADLAMP position, all incandescent back lighting turns ON at the dimming level indicated by the I/P dimmer switch. When the I/P dimmer switch is moved from MIN to MAX, all VF displays, as well as all incandescent back lighting, respond from minimum intensity to maximum brightness in response to the I/P dimmer switch position.
Interior Lights Dimming Schematics
Interior Lighting Systems Description and Operation
Control Module References for scan tool information
Ignition ON, command the Incandescent Dimming ON and OFF with a scan tool. The backlighting should change from high intensity to low intensity when commanded.
⇒ | If the backlighting does not change when commanded, refer to Interior Backlighting Malfunction. |
⇒ | If the backlighting changes when commanded, refer to I/P Dimmer Switch Malfunction. |
⇒ | If the test lamp does not illuminate, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM. |
⇒ | If less than the specified range, test the 10-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM. |
⇒ | If greater than the specified range, test the 10-volt reference circuit for a short to voltage. If the circuit tests normal, replace the BCM. |
⇒ | If less than the specified range, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM. |
⇒ | If the test lamp illuminates, test the signal circuit for a short to ground. If the circuit tests normal, replace the BCM. |
⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. |
⇒ | If greater than the specified value, test the ground circuit for an open/high resistance. |
⇒ | If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM. |
⇒ | If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for BCM replacement, setup, and programming |