Instruments - False Low Oil Level Message
9222buick04
Bulletin: 89-6-15
Date: July, '89
Ref. No.: 89-174-6
Corp. Ref. No.: 91810
SUBJECT:
LOW OIL LEVEL MESSAGE OPERATION
MODELS AFFECTED:
1988-89 RIVIERAS AND REATTAS
Some 1988-1989 Rivieras/Reattas, may exhibit an intermittent false low oil level warning message due to an inoperative oil level sensor.
Important:
1. Some customers may confuse oil pressure warnings with low oil level messages. It is critical identify which oil warning message (pressure or level) was displayed before attempting to repair an oil warning condition.
2. With oil level sensor inoperative all the time, 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, Part Number 1649745, has been released. The new sensor requires a gasket or seal which must be ordered separately as Part Number 25531045. The seal must be replaced whenever a sensor is replaced. 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 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", replace the sensor.
^ If the BI88 changes 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).
^ In Diagnostics, monitor 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 Systein Operation/Component Location:
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 or more since the last engine run cycle.
Example:
If the engine was running at 90~ C coolant temp at key off and is at 85~ C coolant temp at key on, the BCM will ignore oil level sensor input. If the engine is at 90~ 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.
The Oil Level Sensor component location for all model years is shown in the 1988 Final Edition Service Manual on page 8A-201-3 Figure B.
WARRANTY INFORMATION
Labor Operation Number: N4580
Labor Time: 0.4 Hours
Trouble Code: 92