Allante V8-273 4.5L (1991)
Oil Level Sensor: Customer Interest
Low Oil Level Sensor - False Low Oil Level Message
Bulletin No.
T-91-61
File in Group
8
Number
134
Corp. Ref. No.
918108R
Date
March, 1991
SUBJECT:
LOW OIL LEVEL MESSAGE OPERATION, DIAGNOSIS, AND NEW OIL LEVEL SENSOR SERVICE PART
RELEASED
MODELS AFFECTED:
1987-1991 ALLANTES
This bulletin is being revised to include additional model years, new diagnostic information for step 3, and new warranty information.
Some 1987-1991 Allantes 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 to 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/Component Location", which follows.
3.
Vehicles that have been parked at an angle (i.e., on a hill or two wheels in a ditch) either front to back or side to side may exhibit a false low
oil message. The angle of the vehicle causes the oil in the oil pan to flow away from the oil level switch. This condition is normal and will not
be corrected by replacing the oil level switch or oil pan.
A new sensor, P/N 1649745, has been released. The new sensor requires a new seal which must be ordered separately as P/N 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 B164. 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 BI64 changes to "LO", replace the sensor.
^
If the BI64 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 BI64 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 O 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/Component Location:
