Circuit Description
The body control module (BCM) receives a variable voltage from the instrument panel lamp dimmer switch. The BCM uses this signal in order to vary the illumination level of the instrument panel lamps. The instrument panel dimming lamps output from the BCM is a pulse width modulated voltage supply used to light the instrument panel lamps. If a malfunction occurs in the instrument panel dimming lamps output circuit, this DTC is set.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B2628 Display Dimming Pulse Width Modulation (PWM) Output Circuit High
Conditions for Running the DTC
The park lamp input is active (park or headlamps on).
Conditions for Setting the DTC
Any of the following conditions will set this DTC:
The instrument panel dimming lamps output is shorted to voltage.
Action Taken When the DTC Sets
If the instrument panel dimming lamps output is shorted to voltage, the instrument panel lamps will illuminate at full intensity.
Conditions for Clearing the DTC
| • | The conditions for setting the DTC are no longer present. |
| • | A history DTC clears after 100 malfunction free ignition cycles. |
| • | The BCM receives the clear code command from the scan tool. |
Diagnostic Aids
If the DTC is a history DTC, the malfunction may be intermittent. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Interior Lights Dimming Schematics | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
2 |
Do the instrument panel lamps vary with dimmer control? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
3 | Is DTC B2622 or B2623 set? | Go to Step 4 | |
4 | Test for a short to voltage on the instrument panel lamps supply voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 7 | Go to Step 5 |
5 | Inspect for poor connections at the harness connector of the body control module (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 7 | Go to Step 6 |
6 | Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup and programming. Did you complete the replacement? | Go to Step 7 | -- |
7 |
Does the DTC reset? | Go to Step 2 | System OK |
