Low Oil Level Sensor - False Warning Message
90oldsmobile11SUBJECT LOW OIL LEVEL MESSAGE OPERATION
(DIAGNOSIS AND NEW OIL LEVEL SENSOR AND OIL PAN RELEASED)
MODELS/YEARS 1988-90 TORONADO AND TROFEO
NUMBER: 90-T-179
CORP.REF.NO: 918108R
DATE: November 1990
SECTION: 8D2
Some 1988-1990 Toronados and Trofeos 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 wfth 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", which follows.
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 on cars with 3800 (LN3) VIN C engines. 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.
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 value reads "HI" with oil level OK, disconnect the oil level sensor connector and jumper the harness
terminals together.
^ If the BI88 changes to "LO":
For 1988 Toronado's/Trofeo's; replace the sensor.
1989-1990 Toronado's/Trofeo's; replace the oil pan, oil pump screen, dipstick, and sensor.
^ If the BI88 changes remain "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).
^ In Diagnostics, monitor BI88 while moving the 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, the 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, 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~C (59~F) or more since the last engine run cycle. Example: If the engine was running at 90~C (194~F) coolant temp at key "OFF" and is at 85~C (185~F) coolant temp at key "ON", the BCM will ignore oil level sensor input. If the engine is at 90~C (194~F) at key "OFF" and is at 25~C (77~F) 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.
The oil level sensor component location for all model years is shown in the 1990 Toronado/Trofeo Service Manual on page 8A-201-0, Figure A.
For oil pan replacement procedure, refer to Section 6A8 in the 1990 Toronado/Trofeo 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: