Circuit Description
The body control module (BCM) receives a variable voltage signal from the instrument panel (I/P) dimmer switch requesting to illuminate the instrument panel controls illumination lamps to a desired intensity. When this occurs, the BCM directly sends a variable voltage based on the I/P dimmer switch position on the backlight lamps control circuit, instrument panel lamps dimming control circuit, and the LED dimming signal circuit.
Voltage for the backlight lamps control circuit, instrument panel lamps dimming control circuit, and the LED dimming signal circuits is from the TBC 3 fuse 16 in the underhood fuse block directly through the BCM to these circuits.
Conditions for Running the DTC
The battery voltage must be between 9.0-16.0 volts.
Conditions for Setting the DTC
| • | The backlight lamps control circuit is open, shorted to ground, or shorted to voltage. |
| • | The instrument panel lamps dimming control circuit is open, shorted to ground, or shorted to voltage. |
| • | The LED dimming signal circuit is shorted to ground. |
| • | There is a loss of the underhood fuse block TBC 3 battery supply voltage to the BCM for 1 second. |
Action Taken When the DTC Sets
The instrument panel illumination lamps and the controls illumination lamps will not operate or are always ON.
Conditions for Clearing the MIL/DTC
| • | This DTC will clear on current status after the condition for setting the fault is corrected. |
| • | A history DTC will clear after 100 consecutive ignition cycles without a fault present. |
| • | History and current DTCs can be cleared using a scan tool. |
Diagnostic Aids
| • | Perform a visual inspection for loose or poor connections at all related components. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
| • | A short to ground in the following circuits will cause the TBC 3 fuse to open. |
| - | The backlight lamps control. |
| - | The instrument panel lamps dimming control. |
| - | The LED dimming signal. |
| - | Battery positive voltage from the underhood fuse block TBC 3 fuse. |
| • | An open in the TBC 3 fuse will cause the BCM to set the following DTC: |
| - | B0951 |
| - | B2610 |
| - | B2625 |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step test determines if the problem exists in the headlamp switch or the BCM.
-
After replacement of the BCM you must calibrate the new module for proper operation.
Step | Action | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Interior Lights Dimming Schematics Connector End View Reference: Lighting Systems Connector End Views or Body Control System Connector End Views in Body Control System | |||||||||
1 | Did you perform the Lighting System Diagnostic System Check? | Go to Step 2 | |||||||
2 | Is the TBC 3 fuse in the under hood fuse block open? | Go to Step 3 | Go to Step 4 | ||||||
3 | Test the following circuits for a short to ground:
Did you find and correct the condition? | Go to Step 11 | Go to Step 8 | ||||||
4 | Test the backlight lamps control circuit and the instrument panel lamps dimming control circuit for an open, high resistance, short to voltage or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 11 | Go to Step 5 | ||||||
With the headlamp switch still connected, connect a test lamp between the backlight lamps control circuit and the instrument panel lamps dimming control circuit of the headlamp switch connector. Does the test lamp illuminate? | Go to Step 6 | Go to Step 7 | |||||||
6 | Inspect for poor connections at the harness connector of the headlamp switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 11 | Go to Step 9 | ||||||
7 | Inspect for poor connections at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 11 | Go to Step 10 | ||||||
8 | Repair the battery positive voltage circuit of BCM from the TBC 3 fuse in the under hood fuse block. Did you complete the repair? | Go to Step 11 | -- | ||||||
9 | Replace the headlamp and panel dimmer switch. Refer to Headlamp Switch Replacement . Did you complete the replacement? | Go to Step 11 | -- | ||||||
|
Important: Perform the setup procedure for the BCM. Replace the body control module (BCM). Refer to Body Control Module Replacement in Body Control System. Did you complete the replacement? | Go to Step 4 | -- | |||||||
11 |
Does the DTC reset? | Go to Step 2 | System OK | ||||||
