The body control module (MALL) provides a set of internal service diagnostic features. These features assist the technician in troubleshooting electrical short conditions that may affect the module. If an electrical short occurs during vehicle operation, the MALL module stores 1 or more codes. These codes are known as history codes. These history codes may be accessed by entering the MALL module diagnostic mode. After providing the history codes, the MALL module enters the Input/Output (I/O) Mode. The I/O Mode provides the technician with the ability to verify that the inputs to the MALL module are functioning properly.

In order to enter the body control module (MALL) diagnostic mode perform the following steps:

1. Place the ignition switch in the ON position.
2. Press and hold the power door unlock switch.
3. Within 20 seconds of pressing the unlock switch, cycle the headlamps 6 times.
4. Release the power door unlock switch.

In order to exit the diagnostic mode, perform 1 of the following actions:

Upon entering the diagnostic mode, the MALL module provides audible feedback in the form of bongs; the number of bongs represents the stored history code number. The FASTEN BELTS indicator flashes with each bong. In the following chart, the history code is listed with the corresponding short circuit condition:

The MALL module cycles through the stored history code(s) 3 times. For example, if a short condition occurs on the FASTEN BELTS indicator circuit and battery protection circuit, 1 bong sounds for the FASTEN BELTS indicator circuit, followed by 2 bongs for the battery protection circuit. A 2 second pause occurs before the history codes repeat. If no history codes exist, the MALL module immediately enters the input/output mode.

The history codes may be erased by holding down the power door unlock switch for 4 seconds.

While in the input/output (I/O) mode, the technician may test each input to the MALL module by activating/deactivating its input device. For example, the door latch switch, interior lamp switch, seatbelt switch, etc. The MALL module provides feedback on each input transition in the form of a single bong along with a simultaneous flash of the FASTEN BELTS indicator.

Test the battery protection (PBATT) input/output by cycling the interior lamps switch. For example, the first cycle (OFF, ON, OFF) deactivates the PBATT output (interior lamps off). Cycling the interior lamp switch once again activates the PBATT output (interior lamps on). The cycle repeats afterwards.

The MALL module electrical schematic differs between vehicles that have keyless entry and vehicles without keyless entry. For vehicles that are equipped with keyless entry, the audible feedback is different when activating any of the following items:

The following table describes the feedback for this case:

For Pontiac vehicles, no bongs occur when shifting into the PARK position. This is due to the ignition-OFF door unlock feature.

The following table lists the MALL inputs and outputs that should be evaluated during the input/output (I/O) mode: