B2457

DTC B2457 Theater Dimming 2 Open or Shorted to GND:

CIRCUIT DESCRIPTION
The BCM controls the interior illumination. The BCM turns on the roof rail courtesy/reading lamps and the inside rear view mirror lamps when:
^ Any vehicle door is opened.
^ The I/P dimmer switch is in the DOME position.
^ During exit illumination or delayed illumination.
^ Lifting either LF or RF door handle.
^ When unlocking the doors using the keyless entry transmitter.

The BCM turns oft the lamps when all doors are closed and the I/P dimmer switch is oft.

All vehicle doors contain a door lock ajar switch. When the driver's door is open, the LF door lock ajar switch closes and sends a ground signal to the BCM through circuit 49. When the LF, RF, LR or RR door is open, its corresponding door lock ajar switch closes and sends a ground signal to the BCM through circuit 727. The LF and RF door locks have a door handle switch. When either LF or RF door handle is lifted, its corresponding door lock switch sends a ground signal to the BCM through circuit 394. The BCM grounds circuit 157 when detecting a ground signal in circuit 49, 394 or 727. When the driver's door is closed, the LF door lock ajar switch opens circuit 49. When the LF, RF, LR and PR doors are closed, their corresponding door lock ajar switches open circuit 727. When LF and RF door handles are released, circuit 394 opens. The BCM then opens circuit 157 when circuit 49, 394 and 727 are open.

The BCM uses the voltage in circuit 240 to power the courtesy lights through circuit 1732. The BCM controls the power supplied in circuit 1732 for inadvertent load (battery rundown) protection. The BCM opens circuit 157 when the inadvertent load (battery rundown) protection is active (circuit 1732 is open).

CONDITIONS FOR SETTING THE DTC
^ The BCM detects a short to ground or an open in circuit 157 for more than 0.15 seconds.
^ The BCM detects an open in circuit 1732.

ACTION TAKEN WHEN THE DTC SETS
The BCM stores DTC 62457 in memory.

CONDITIONS FOR CLEARING THE DTC
^ The BCM no longer detects a short to ground in circuit 157.
^ The BCM no longer detects an open in circuit 157 or 1732.
^ A history DTC will clear after 100 consecutive ignition cycles if the condition for the fault is no longer present.
^ Using a scan tool.

DIAGNOSTIC AIDS
^ The following conditions may cause an intermittent malfunction to occur:
^ An intermittent short to ground in circuit 157.
^ An intermittent open in circuit 157 or 1732.
^ The BCM is shorted to ground or open internally.
^ If the DTC is a history DTC, the problem may be intermittent. Try performing the tests shown while wiggling wiring and connectors, this can often cause the malfunction to reappear.
^ DTC P1626 will set in the PCM when the ignition switch is on with the BCM disconnected.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
3. This step checks for a short to ground in circuit 157.
4. This step checks for an open in circuit 157.
5. This step determines whether the malfunction is intermittent or the BCM is faulty.