B2620

DTC B2620

CIRCUIT DESCRIPTION
The body control module (BCM) directly sends a 5 volt reference voltage to the instrument panel (I/P) dimmer switch which is then adjusted based on the I/P dimmer switch position and returned as a low reference and a signal to the BCM. The BCM uses this signal to directly control the desired level of instrument panel illumination lamp intensity.

CONDITIONS FOR RUNNING THE DTC
The battery voltage must be between 9.0-16.0 volts.

CONDITIONS FOR SETTING THE DTC
- When the BCM monitors a 5 volt reference circuit voltage of less than 4.5 volts.
- When the BCM monitors a 5 volt reference circuit voltage of greater than 5.5 volts.
- When the BCM monitors a signal voltage of equal or greater than 4.86 volts for more than 1 second.

ACTION TAKEN WHEN THE DTC SETS
The instrument panel illumination lamp dimming will not operate.

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.

TEST DESCRIPTION

Steps 1-2:

Steps 3-5:

Steps 6-10:

Steps 11-16:

The numbers below refer to the step numbers on the diagnostic table.
3. Tests for the proper operation of the circuit in the low voltage range.
4. Tests for the proper operation of the circuit in the high voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to ground.
5. Tests for a short to voltage in the 5 volt reference circuit.
6. Tests for a high resistance or an open in the low reference circuit.