MALL Diagnostic Procedures<--------------------------------------------*Bong Test*
 

MALL Diagnostic Procedures..this covers 1996 to 1999 Bonneville
Problem:
Power door locks, interior lamps, and “Key-In-Ignition” and/or “Fasten Seat Belt” chime do not function or interior lights stay on all the time

Component Diagnosis:Body Control Module (BCM) AKA....Multifunction Alarm Lock Light (MALL,module)

First Steps:
1. Check door lock fuse (Fuse 1 - 20 amp) and chime fuse (Fuse 1D – 15 amp)
2. Check Courtesy Lamp/Power Mirror fuse (Fuse 6A – 15 amp)
3. Check for poor terminal contact at MALL and wiring harness connectors
4. Check for broken or partially broken wires.

Second Step: Perform the “MALL Module Internal Diagnostic Procedure/Bong Test"

The MALL module stores “history” codes if an electrical short occurs in the system during vehicle operation. The codes are “communicated audibly (a bong sound) by accessing the MALL module diagnostic mode. After providing any codes, the MALL module enters a functional test mode (called Input/Output or “I/O”) to assist in verifying that the inputs to the MALL are functioning properly.

1. To enter MALL module diagnostic mode/Bong Test:
a. Turn ignition switch to “ON”
b. Press AND hold the power door unlock switch while at the same time…
c. Cycling the headlamp switch six times, on and off, within 20 seconds of pressing and holding the power door unlock switch
d. Release power door unlock switch

Note: (To “Exit” the MALL module diagnostic mode, turn the ignition switch to “OFF”.)

The MALL will provide a number of audible “bong” sounds (and flash the “Fasten Seat Belt” indicator light with each bong) to identify the stored history codes for any malfunctions (short circuits) as follows:

# of “bongs” Circuit Short Condition
One: Fasten Seat Belt Circuit
Two: Battery Protection Circuit
Three: Courtesy Lamps Circuit

The MALL module will cycle through the stored history code(s) three times pausing for two seconds between each of the three cycles.

If no codes exist the MALL immediately enters the I/O mode. (Input/Output)

2. I/O Mode:

In the I/O mode, input from components in the system are “tested” by activating/deactivating each components input device and providing either one “bong”or NO, bongs (along with flashing the “Fasten Seat Belt” indicator light) to indicate whether a “short” is detected in the circuit as follows:

Component-------------------------------------------------Test
Auxiliary Chime --------------------------------------------Apply Parking Brake/Release, then Repeat
Interior Lamps-----------------------------------------------Turn on interior lamp switches, then turn off, then Repeat
Dome Lamp -------------------------------------------------Turn on dome lamps, then turn off, then Repeat
Door Latch Switches ------------------------------------ LH and RH Door latch switches, lift up handle only don't open,Repeat
Power Door Locks------------------------------------------Lock then Unlock, Repeat
Battery Protection------------------------------------------Turn on interior lamp switch, then turn off, then Repeat
“Lamps On” Chime ----------------------------------------Turn on headlight switch, then turn off, then Repeat
Fasten Seat Belts Chime and Indicator Light-----Latch, then unlatch driver’s Seatbelt, then repeat.
"Turn Signal On" Reminder Chime--------------------Activate turn signal, then turn off, then Repeat
Trunk Lid Ajar Light ----------------------------------------Activate/deactivate trunk lid latch switch, then repeat.

If you get a “bong” when testing a component, then the component is functioning properly.

If these components check out OK, then the MALL module itself needs to be tested for a short or the module may need to be replaced.