LOW OIL LEVEL MESSAGE OPERATION/DIAG. & NEW PART
SUBJECT: LOW OIL LEVEL MESSAGE OPERATION (DIAGNOSIS AND NEW OIL , LEVEL SENSOR AND OIL PAN RELEASED)
MODELS AFFECTED: 1988-90 RIVIERA/REATTA
THIS BULLETIN IS BEING REVISED TO INCLUDE OIL PAN KIT AND SERVICE INFORMATION. PLEASE DISCARD 90-6-3 (CORPORATION NO. 918108R).
Some 1989-1990 Buick Rivieras/Reattas may exhibit an intermittent false low oil level warning message due to either an inoperative oil level sensor or a misformed oil pan.
IMPORTANT:
1. Some customers may confuse oil pressure warnings with low oil level messages. It is critical to identify which oil warning message (pressure or level) was displayed before attempting to repair an oil warning condition.
2. With either an oil level sensor inoperative all the time or a misformed oil pan, the message will appear to be intermittent because of the way that the oil level is tested by the body computer. See "Oil Level Sensor System Operation", in this bulletin.
A new sensor, P/N 1649745, has been released. The new sensor requires a gasket or seal which must be ordered separately as P/N 25531045. The seal must be replaced whenever a sensor is replaced.
A new oil pan has been released for service and 1990 production on cars with 3800 engines built on or after July 2, 1990. The engine build date can be found on a sticker on the rear valve cover and can be viewed by looking past the brake master cylinder from the driver's side of the car. The new pan requires a new gasket, oil pump screen, oil pump screen gasket, and dipstick. These parts can be ordered through GMSPO as a kit using P/N 12350269.
NOTE:
Oil Pan Kit, Part No. 12350269, may also be used to correct an oil pan leak on 1989-90 Rivieras/Reattas. Please reference Bulletin 90-6-12 for details.
Parts are currently available from GMSPO.
TO DIAGNOSE LOW OIL LEVEL MESSAGES:
1. Check the oil level using the dipstick.
2. Turn the key to on with the engine off. If the engine has been running, allow time for the oil to drain back into the oil pan.
3. Enter service diagnostics and monitor BCM Input BI88. If the input is "HI", go to 4A. If the input is "LO", go to 4B.
4A. If the input reads "HI" with the oil level OK, disconnect the oil level sensor connector and jumper the harness terminals together.
o If input BI88 changes to "LO":
- Replace the oil pan, oil pump screen, dipstick, and sensor.
o If input BI88 remains "HI" with the terminals jumpered, check for an open in circuit 114 from the BCM to the sensor; and check the sensor ground circuit for continuity to ground. Repair any wiring faults found and reconnect the sensor. (Go back to step 3.)
4B. If value reads "LO" with oil level OK (possible intermittent sensor or wiring).
o In Diagnostics, monitor input BI88 while cycling wiring and connectors between the oil level sensor and the BCM. Any open circuit between the sensor and BCM or between the sensor and ground will cause the oil level input to be "HI" and could cause a false low oil level message. The X/O status indicator will change from 0 to X if an open occurs.
IMPORTANT:
Due to oil splash the sensor input will change from low to high while driving. This is a normal condition. Perform tests for intermittent sensors at key on, engine off.
OIL LEVEL SENSOR SYSTEM OPERATION:
With proper oil level, input BI88 should be "LO". (The sensor grounds the 5 volt circuit from the BCM when oil level is OK; a ground on the circuit is "LO" in diagnostics.)
If oil level is low, input BI88 should be "HI". (The sensor is open with low oil level and the BCM 5 volt circuit remains at 5 volts; "HI" in diagnostics.)
The BCM only checks oil level at key on when the engine has cooled by 15 degrees C or more since the last engine run cycle. Example: If the engine was running at 90 degrees C coolant temp at key off and is at 85 degrees C coolant temp at key on, the BCM will ignore oil level sensor input. If the engine is at 90 degrees C at key off and is at 25 C at key on, the BCM will check the sensor status. If the status is "HI" or open, the BCM will display a low oil level warning.
For oil pan replacement procedure, refer to Section 6A8 in the Service Information Manual.
IMPORTANT:
Make sure that the engine block and oil pan surfaces are clean and dry. Do not use any sealer or glue on the oil pan, gasket or block as it can cause the gasket to squeeze out and split. Do not follow the oil pan torque specifications found in the Service Manual. Torque engine oil pan bolts to 10 N.m (7 lbs. ft.), then retorque to 16 N.m (12 lbs. ft.).
WARRANTY INFORMATION:
Operation VEHICLE SERIES Operation Description Number RIVIERA/REATTA ------------------------ --------- --------------
Low Oil Level Message - Replace Oil Pan, Gasket, Oil Pump Screen, Dipstick, and Oil Level Sensor T6467 .8
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.
