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 |
|---|---|---|---|---|
I/P Dimming Voltage Reference | B1395 03 | B1395 03 | B1395 07 | -- |
Courtesy Lamp Voltage Reference | B2615 00, B2615 02 | B2615 00, B2615 04 | B2615 00, B2615 01 | -- |
LED Indicator Dimming Volage Reference | B2625 00 | B2625 00 | B2625 00 | -- |
Dome/Reading Lamp Control | B2615 00 | B2615 00 | -- | -- |
Dome/Reading Lamp Supply Voltage | 1 | 1 | -- | -- |
Dome Lamp Switch Signal | 2 | 2 | 2 | -- |
Exterior Lamps Illumination Supply Voltage | 5 | 5 | 5 | -- |
Inadvertent Power Control | 5 | 5 | 5 | -- |
I/P Lamps Dimming Control | B2652 00 | B2652 00 | B2652 00 | -- |
Left Front Door Open Switch Signal | 3 | 3 | 3 | -- |
Left Rear Door Open Switch Signal | 4 | 4 | 4 | -- |
Right Front Door Open Switch Signal | 3 | 3 | 3 | -- |
Right Rear Door Open Switch Signal | 4 | 4 | 4 | -- |
Dome/Reading Lamp Low Control - Driver Door | -- | 1 | -- | -- |
Dome/Reading Lamp Low Control - Passenger Door | -- | 1 | -- | -- |
Exterior Lamps Low Reference | -- | 5 | -- | -- |
I/P Dimmer Switch Ground | -- | 2 | -- | -- |
LH Vanity Mirror Courtesy Lamp Ground | -- | 1 | -- | -- |
Overhead Console Courtesy Lamp Ground | -- | 1 | -- | -- |
Rear Dome Lamp Ground | -- | 1 | -- | -- |
RH Vanity Mirror Courtesy Lamp Ground | -- | 1 | -- | -- |
1. Courtesy Lamps Malfunction 2. Dome Lamp Switch Malfunction 3. Door Open Switch Malfunction - Front 4. Door Open Switch Malfunction - Rear 5. Exterior Lamps Malfunction | ||||
Circuit/System Description
When the ignition switch is turned to the RUN position, the radio VF display turns ON at maximum brightness. When the park lamps are ON, all incandescent and LED back lighting turn ON at the dimming level indicated by the instrument panel (I/P) dimmer switch. At the same time all VF displays dim to match the indicated dimming level. The panel dimmer switch potentiometer is an input to the body control module (BCM). When the driver selects a dimming setting by moving the I/P dimming switch potentiometer, all incandescent back lighting lamps are provided with a specific voltage. 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
Reference Information
Schematic Reference
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 driver door switch while commanding the Driver Door Switch Integrated Sw. Backlighting Test ON and OFF with a scan tool. The switch backlighting should turn ON and OFF between commanded states.
- Ignition ON, observe the driver memory/heated seat switch while commanding the Driver Door Switch Non-Integrated Sw. Backlighting Test ON and OFF with a scan tool. The switch backlighting should turn ON and OFF between commanded states.
- Ignition ON, observe the passenger door switch while commanding the Passenger Door Switch Integrated Sw. Backlighting Test ON and OFF with a scan tool. The switch backlighting should turn ON and OFF between commanded states.
- Ignition ON, observe the passenger heated seat switch while commanding the Passenger Door Switch Non-Integrated Sw. Backlighting Test ON and OFF with a scan tool. The switch backlighting should turn ON and OFF between commanded states.
- Ignition ON, observe the scan tool BCM Dimming Control Signal parameter while operating the dimmer switch from high to low. The reading should change from a high percent to a low percent as the switch is rotated.
| ⇒ | If the backlighting does not turn ON and OFF or remains always ON, replace the driver door lock and side window switch. |
| ⇒ | If the backlighting does not turn ON and OFF or remains always ON, refer to Front Door Switch Backlighting Malfunction. |
| ⇒ | If the backlighting does not turn ON and OFF or always remains ON, replace the passenger door lock and side window switch. |
| ⇒ | If the backlighting does not turn ON and OFF or remains always ON, refer to Front Door Switch Backlighting Malfunction. |
| ⇒ | If the reading does not change, refer to Dimmer Switch Malfunction. |
| ⇒ | If the scan tool dimmer control operates normal, refer to the Interior Backlighting Circuit Test or the LED Dimming Malfunction. |
Circuit/System Testing
Dimmer Switch Malfunction
- Ignition OFF, disconnect the harness connector at the headlamp and panel dimmer switch.
- Ignition OFF, verify that a test lamp illuminates between the ground circuit terminal 8 and B+.
- Ignition ON, verify the scan tool Dimming Control Signal parameter is less than 0.1 volts.
- Ignition ON, test for B+ between the I/P dimming voltage reference circuit terminal 15 and ground.
- Install a 3A fused jumper wire between the signal circuit terminal 13 and the voltage reference circuit terminal 15. Verify the scan tool BCM Dimming Control Signal parameter is greater than 2.6 volts.
- If all circuits test normal, test or replace the headlamp and panel dimmer 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
- Ignition OFF, disconnect the harness connector at the appropriate component.
- Ignition OFF, verify that a test lamp illuminates between the listed ground circuit terminal and B+.
- Connect a test lamp between the listed backlighting control circuit terminal and ground.
- Command the dimming test high to low with a scan tool. The test lamp should turn from bright to dim when changing between the commanded states.
- If all circuits test normal, test or replace the appropriate component.
| • | Rear window switch terminal F |
| • | Headlamp switch terminal 8 |
| • | Transfer case control switch terminal 6 |
| • | Sunroof switch terminal 5 |
| • | Roof beacon switch terminal 1 |
| • | Garage door opener switch terminal 3 |
| • | Folding seat switch terminal 4 |
| • | Power liftgate open/close switch terminal C |
| • | Auxiliary HVAC control module terminal 2 |
| ⇒ | If the test lamp does not illuminate, test the ground circuit for an open/high resistance. |
| • | Rear window switch terminal B |
| • | Headlamp switch (Chevy, GMC) terminal 7 |
| • | Transfer case control switch terminal 5 |
| • | Sunroof switch terminal 3 |
| • | Roof beacon switch terminal 2 |
| • | Garage door opener switch terminal 2 |
| • | Folding seat switch terminal 5 |
| • | Power liftgate open/close switch terminal B |
| • | Auxiliary HVAC control module terminal 1 |
| ⇒ | If the test lamp is always OFF, test the control circuit for an open/high resistance or short to ground. 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. |
LED Dimming Malfunction
- Ignition OFF, disconnect the harness connector at the appropriate component.
- Ignition OFF, verify that a test lamp illuminates between the listed ground circuit terminal and B+.
- Connect a test lamp between the listed LED dimming control circuit terminal and ground.
- Command the dimming test high to low with a scan tool. The test lamp should turn from bright to dim when changing between the commanded states.
- If all circuits test normal, test or replace the appropriate component.
| • | Left steering wheel switch terminal 8 |
| • | Right steering wheel switch terminal 1 |
| • | Headlamp and Panel Dimmer Switch (Cadillac) terminal 8 |
| • | Analog clock terminal 2 |
| • | DIC switch terminal 5 |
| • | Manual HVAC control module terminal 10 X2 |
| • | Multifunction accessory switch (Chevy, GMC) terminal 3 |
| • | Multifunction accessory switch (Cadillac w heated windshield washer and power running boards) terminal 1 |
| • | Multifunction accessory switch (Cadillac w StabiliTrak® and rear park assist) terminal 5 |
| ⇒ | If the test lamp does not illuminate, test the ground circuit for an open/high resistance. |
| • | Left steering wheel switch terminal 6 |
| • | Right steering wheel switch terminal 2 |
| • | Headlamp and Panel Dimmer Switch (Cadillac) terminal 7 |
| • | IPC (Chevy, GMC) terminal 8 |
| • | Radio terminal 7 X1 |
| • | Analog clock terminal 3 |
| • | Rear seat audio controller terminal 7 X1 |
| • | DIC switch terminal 4 |
| • | Manual HVAC control module terminal 1 X2 |
| • | Multifunction accessory switch (Chevy, GMC) terminal 4 |
| • | Multifunction accessory switch (Cadillac w heated windshield washer and power running boards) terminal 3 |
| • | Multifunction accessory switch (Cadillac w StabiliTrak® and rear park assist) terminal 6 |
| ⇒ | If the test lamp is always OFF, test the control circuit for an open/high resistance or short to ground. 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. |
Front Door Switch Backlighting Malfunction
- Ignition OFF, disconnect the harness connector X4 at the door lock and side window switch.
- Connect a 3A fused jumper wire between the low reference circuit terminal 4 and ground.
- Connect a test lamp between the backlight supply voltage circuit terminal 13 and B+. The heated seat switch backlighting should illuminate.
- If the switch backlighting tests normal, replace the door lock and side window switch.
| ⇒ | If the switch backlighting does not illuminate, replace the heated seat switch. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for BCM, door lock and side window switch, IPC, radio, HVAC control module, and rear seat audio controller replacement, setup, and programming. |
