BCM VEHICLE OPTION PARAMETERS DESCRIPTION AND SYMPTOMS

VEHICLES AFFECTED: 1988 BUICK RIVIERA AND REATTA 1988 OLDSMOBILE TORONADOS AND TROFEOS

For Buick:

Two new BCM diagnostic parameters and two new diagnostic overrides have been added to 1988 Rivieras and Reattas. The two new parameters, BD90 "Option 1" and BD91 "Option 2", display numbers that represent the option content of the vehicle. The BCM uses these values to determine how to operate the displays and electronic controls. Incorrect option values may cause the following conditions:

Unwanted headlight operation with the ignition on.

Twilight sentinel inoperative.

Illuminated entry inoperative.

Incorrect display-on-entry on CRT (Riviera displays "REATTA" on CRT or Reatta displays "RIVIERA" on CRT) .

Tape deck inoperative ("EJECT" and "PLAY" keys do not appear on CRT).

"Electrical Problem" message and BCM code B332 set.

Loss of compass display (on cars with a compass).

Low washer fluid indication inoperative.

Low oil level indication inoperative.

CRT warning messages appear with numbers above the return key.

Unwanted fog lamp operation with ignition on.

BCM codes B120 and B420 set current on cars without twilight sentinel (option code T82)

BD90 and BD91 values may be corrected if necessary by using BCM overrides BS07 and BS08 respectively. Use the following procedure to determine the correct option values and change the option values if they are incorrect:

1. Determine the proper option values. Option I (parameter BD90) contains the status of the following options: U.S./Canadian displays, twilight sentinel, domestic/export displays, illuminated entry, body style (Riviera or Reatta). Option 2 (parameter BD91) contains the status of ABS (Anti-Lock Brake System), theft deterrent, compass, tape deck, oil level sensor, and washer fluid level sensor. The status of many of these options will be the same for all cars (e.g. tape deck), but for others it may be necessary to consult the option content sticker on the deck lid. After determining the option status, use the tables below to calculate the proper option values:

OPTION 1:

If The Vehicle is Equipped with: Add

U.S. Car (All except Canadian cars, option code Z49, and export cars, option code NM8) 128 Export Displays (option code NM8) 32 Reatta Body Style 16 Twilight Sentinel (option code T82) 2 Total

Example: A Reatta (16) is a domestic U.S. car (128) with an twilight sentinel (2). The proper value for Option 1 is 128 (U.S. car) + 16 (Reatta body style) + 2 (twilight sentinel) = 146.

OPTION 2:

If The Vehicle is Equipped with: Add

Washer fluid level sensor (all cars) 128 Theft deterrent (option code UA6) 64 ABS (option code JL9) 32 Compass (option code UC3) 16 Tape deck (all cars) 8 Oil level sensor (all 1988 cars) 4 Total

Example: A vehicle has a washer fluid level sensor (128), theft deterrent (64), a tape deck (8), and an oil level sensor (4). The proper value for Option 2 is 128 (washer fluid level sensor) + 64 (theft deterrent) + 8 (tape deck) + 4 (oil level sensor) = 200.

2. Once the proper option values are calculated, check the actual values of Option 1 (BD90) and Option 2 (BD91) in diagnostics. These values should be the same as the values calculated using the tables above. If the values are correct and the customer comment remains, refer to the Service Manual Section 8D for diagnosis. If the values are incorrect, proceed to step 3.

3. If the option values are not correct, they may be corrected in diagnostics using BCM overrides BS07 for Option 1 and BS08 for Option 2. Enter diagnostics and select the proper override (BS07 or BS08). Using the up and down arrow keys on the CRT, change the option value up or down to the proper value.

When the proper value is displayed, press and hold the "GAGES" and "OPTION" buttons on the CRT for three seconds (the override value displayed will blank momentarily). This will write the current option value over the previous value in the BCM EEPROM where the Option 1 and Option 2 values are stored. NOTE: Repeated writing to the BCM EEPROM may cause EEPROM failure. This procedure should only be per-formed to repair incorrect option values.

For Oldsmobile:

Two new BCM diaanostic parameters and two new diagnostic overrides have been added to 1988 Toronados and Trofeos. The two new parameters, BD90 "Option 1" and BD91 "Option 2", display numbers that represent the option content of the vehicle. The BCM uses these values to determine how to operate the displays and electronic controls. Improper option values may cause the following conditions:

Unwanted headlight operation with the ignition on.

Twilight sentinel inoperative.

Oil pressure gage inoperative.

Numbers appear following messages displayed on the driver information center.

BCM codes B120 and B420 set current on cars without twilight sentinel (option code T82).

BD90 and BD91 values may be corrected if necessary by using BCM overrides BS07 and BS08, respectively. Use the following procedure to determine the proper option values, and change the option values if they are improper:

1. Determine the proper option values. Option 1 (parameter BD90) contains the status of the following options: U.S./Canadian displays, twilight sentinel, domestic/export displays, oil pressure sensor. Option 2 (parameter BD91) contains the status of ABS (Anti-Lock Brake System). The status of many of these options will be the same for all cars (e.g. oil pressure sensor), but for others it may be necessary to consult the option content sticker on the deck lid. After determining the option status, use the tables below to calculate the proper option values:

OPTION 1:

If The Vehicle is Equipped with: Add

U.S. Car (All except Canadian cars, option code Z49, and export cars, option code NM8) 128 Dornestic Displays (All except export cars, option code NM8) 32 Twilight Sentinel (option code T82) 64 Oil Pressure Sensor (All 1988 cars) 8 Total

Example: For a domestic U.S. car with an oil pressure sensor and twilight sentinel, the proper value for Option 1 is 128 (U.S. car) + 64 (twilight sentinel) + 32 (domestic displays) + 8 (oil pressure sensor) = 232.

OPTION 2:

If The Vehicle is Equipped with: Add

ABS (option code JL9) 16 Total

If the vehicle has ABS, Option 2 should be 16. If the vehicle does not have ABS, Option 2 should be 0.

2. Once the proper option values are calculated, check the actual values of Option 1 (BD90) and Option 2 (BD91) in diagnostics. These values should be the same as the values calculated using the tables above. If the values are correct and the customer complaint remains, refer to the Service Manual Section 8D for diagnosis. If the values are improper, proceed to step 3.

3. The option values may be corrected in diagnostics using BCM overrides BS07 for Option 1 and BS08 for Option 2. Enter diagnostics and select the proper override (BS07 or BS08). Using the Cool/Warm button, change the option value up by pressing "WARM" or down by pressing "COOL" to the proper value. When the proper value is displayed, press and hold the "LOWER" and "DEF" buttons on the ECC panel for three seconds (the override value will blank momentarily). This will write the current option value over the previous value in the BCM EEPROM where the Option 1 and Option 2 values are stored. NOTE: Repeated writing to the BCM EEPROM may cause EEPROM failure. This procedure should only be performed to repair incorrect option values.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.