B2622

DTC B2622

CIRCUIT DESCRIPTION
The body control module (BCM) supplies a reference voltage to the instrument panel dimmer switch through the instrument panel (I/P) lamps dimmer control circuit. The dimmer switch varies the voltage and returns the new voltage to the BCM through the low reference circuit. The BCM uses this voltage to determine the illumination level of the I/P lamps.

DTC DESCRIPTOR
This diagnostic procedure supports the following DTC:
DTC B2622 Display Dimming Pulse Width Modulation (PWM) Input Circuit Low

CONDITIONS FOR RUNNING THE DTC
The park lamp input to the BCM is active, park or headlamps ON.

CONDITIONS FOR SETTING THE DTC
Any of the following conditions will set this DTC:
- The I/P lamps dimmer control circuit is shorted to ground.
- The low reference circuit is shorted to ground.

ACTION TAKEN WHEN THE DTC SETS
The illumination of the I/P lamps defaults at full intensity.

CONDITIONS FOR CLEARING THE DTC
- The BCM receives the clear code command from the scan tool.
- A current DTC will clear when the conditions for setting the DTC are no longer present.
- A history DTC clears after 100 malfunction free ignition cycles.

DIAGNOSTIC AIDS
If the DTC is a history DTC, the problem may be intermittent.

TEST DESCRIPTION

Step 1 - Step 9:

The numbers below refer to the step numbers on the diagnostic table.
2. The normal operating voltage of the I/P dimmer switch is 0.4-4.5 volts.
3. This step determines if there is a problem with the dimmer switch.