Diagnostic Instructions
| • | 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. |
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
DIM Fuse B+ Terminal 2 X2 | B1395 03 | B1395 03 | -- | -- |
DIM Fuse B+ | B2652 00 | B2652 00 | -- | -- |
I/P Dimmer Switch B+ Voltage Reference | B1395 03, B3600 03 | B3600 03 | -- | -- |
I/P Lamps Dimmer Switch Signal | B2652 00 | 2 | 2 | -- |
I/P Dimmer Switch Signal | B1395 03, B3600 03 | B3600 03 | 1 | -- |
LED Backlight Dimming Control | B2610 00 | 3 | 3 | -- |
I/P dimmer Switch Ground | -- | 1 | -- | -- |
1. Dimmer Switch Malfunction 2. Interior Backlighting Malfunction -- Incandescent 3. Interior Backlighting Malfunction -- LED | ||||
Circuit/System Description
The instrument panel (I/P) lamp dimmer switch is used to increase and decrease the brightness of the interior backlighting components. The I/P dimmer switch provides a voltage signal that will increase as the brightness of the lights are increased and decrease as the brightness of the lights are decreased. The body control module (BCM) provides a B+ voltage reference to the I/P dimmer switch. When the I/P dimmer switch is placed in the desired position, the dimmed voltage setting is applied from the I/P dimmer switch through the I/P dimmer switch signal circuit to the BCM. The BCM interprets the signal and applies the dimmed voltage to the I/P lamps supply voltage circuit and the interior backlighting components dim to the requested level. Ground for the I/P dimmer switch is provided at G201.
Reference Information
Schematic Reference
Interior Lights Dimming Schematics
Connector End View Reference
Description and Operation
Interior Lighting Systems Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Ignition ON, observe the scan tool Dimming Control Signal parameter while operating the dimmer switch from high to low. The parameter should change from a high percent to a low percent as the switch is activated.
| ⇒ | If the parameter does not change, refer to I/P Dimmer Switch Malfunction. |
| ⇒ | If the parameter changes, refer to Interior Backlighting Malfunction. |
Circuit/System Testing
I/P Dimmer Switch Malfunction
- Ignition OFF, disconnect the harness connector at the headlamp switch.
- Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal 4.
- Ignition ON, verify the scan tool Dimming Control Signal parameter is less than 0.0 volts.
- Ignition ON, test for B+ between the voltage reference circuit terminal 12 and ground.
- Install a 3A fused jumper wire between the signal circuit terminal 13 and the voltage reference circuit terminal 12. Verify the scan tool Dimming Control Signal parameter is greater than 2.5 volts.
- If all circuits test normal, test or replace the headlamp switch.
| ⇒ | If the test lamp does not illuminate, test the ground circuit for an open/high resistance. |
| ⇒ | If greater than the specified range, test the signal circuit terminal 13 for a short to voltage. If the circuit tests normal, replace the BCM. |
| ⇒ | If less than the specified value, test the voltage reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM. |
| ⇒ | If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM. |
Interior Backlighting Malfunction - Incandescent
- Ignition OFF, disconnect the harness connector at the component with the inoperative incandescent backlighting.
- Ignition OFF, scan tool OFF, interior lamps OFF, doors CLOSED, test for less than 5 ohms between the ground circuit terminal and ground.
- Connect a test lamp between the control circuit and ground.
- Command the Incandescent Dimming Control ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
- If all circuits test normal, test or replace the component with the inoperative incandescent backlighting.
| ⇒ | If greater than the specified range, 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. |
Interior Backlighting Malfunction - LED
- Ignition OFF, disconnect the harness connector at the component with the inoperative LED backlighting.
- Ignition OFF, scan tool OFF, interior lamps OFF, doors CLOSED, test for less than 5 ohms between the ground circuit terminal and ground.
- Connect a test lamp between the control circuit and ground.
- Command the LED Dimming Control ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
- If all circuits test normal, test or replace the component with the inoperative LED backlighting.
| ⇒ | If greater than the specified range, 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. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for BCM, HVAC, IPC, or Radio replacement, setup, and programming |
