Test Description

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The number(s) below refer to the step number(s) on the diagnostic table.

2. Listen for an audible click when the courtesy lamp relay operates. Command both the ON and OFF states. Repeat the commands as necessary.
3. Tests for voltage at the coil side of the courtesy lamp relay. The CTSY fuse supplies power to the coil side of the courtesy lamp relay.
4. Verifies that the body control module is providing ground to the courtesy lamp relay.
5. Tests if ground is constantly being applied to the courtesy lamp relay.
12. After replacement of the BCM you must calibrate the new module for proper operation.

Fig 1: DTC B2618 (Steps 1-2)

Courtesy of GENERAL MOTORS CORP.

Fig 2: DTC B2618 (Steps 3-13)

Courtesy of GENERAL MOTORS CORP.