B2457

Diagnostic Chart:

Schematic:

CIRCUIT DESCRIPTION
The SBM controls the theater dimming. The SBM grounds the lamps directly. The output fades out in order to turn the lamps to the OFF position. If there is an open or a short to ground in the Theater Dim #2 control circuit, a fault condition is present and a DTC will set.

CONDITIONS FOR SETTING THE DTC
The SBM detects a short to ground or an open in the Theater Dim #2 control circuit for more than 0.15 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ Stores the DTC B2457 in the SBM memory
^ No driver warning message will be displayed for this DTC.

CONDITIONS FOR CLEARING THE DTC
^ A short to ground is no longer detected by the SBM on the Theater Dim #2 control circuit.
^ An open is no longer detected by the SBM on the Theater Dim #2 control circuit.
^ A history DTC clears after 50 consecutive ignition cycles if the condition for the fault is no longer present.
^ Using the on-board diagnostic (clearing DTC) feature.
^ Using a scan tool.

DIAGNOSTIC AIDS
The following conditions may cause an intermittent malfunction to occur:
^ An intermittent short to ground in the Theater Dim #2 control circuit
^ An intermittent open in the Theater Dim #2 control circuit
^ A short to ground or an open internal to the SBM If the DTC is a history DTC, the problem may be intermittent. Perform the tests shown while wiggling the wiring and connectors. This can often cause the malfunction to appear.

TEST DESCRIPTION
The number(s) below refer to the step number(s) on the diagnostic table.
2. This step test the theater dim #2 control circuit for a short to ground or and open circuit.