SERVICE MANUAL UPDATE-SEC. 8A 2 POSITION OIL PRESSURE GAGE

SUBJECT: ADDITIONAL INFORMATION FOR TWO POSITION OIL PRESSURE INDICATOR GAUGE

MODElS/YEARS: 1992 CUTLASS SUPREME

Some 1992 Oldsmobile Cutlass Supreme models were built with a standard Oil Pressure Gage and some models were built with a Two-Position Oil Pressure Indicator. This bulletin provides the necessary diagnostic information for Two-Position Oil Pressure Indicator System Faults ONLY.

The indicator will point to low oil pressure with the ignition switch in "RUN" with the engine NOT running. When the engine is running, normal oil pressure opens the Oil Pressure Switch and the indicator will move to mid-scale.

For the sake of efficiency, complete service manual pages are provided only where necessary. Pages with minor addtions are displayed as page titles, page numbers and the updated information. For clarity, when necessary, a brief note explains where the update would be inserted in the page.

Please mark a reference to this bulletin on the appropriate pages in Section 8A of the 1992 Cutlass Supreme Service Manual.

INSTRUMENT CLUSTER: GAUGES

F: OIL PRESSURE GAUGE INDICATES LOW

1. Check oil level and pressure with a mechanical gage.

If oil level and pressure are OK, go to Step 2.

If oil level and pressure are not OK, see Section 6 for diagnosis.

2. With Ignition Switch in RUN, disconnect the Fuel Pump/Oil Pressure Switch connector.

If the OIL Pressure Gauge reads normal, check for a poor connection. If OK, replace the Fuel Pump!Oil Pressure Switch.

If the OIL Pressure Gauge still reads low, check/repair TAN (31) wire for a short to ground (see schematic). If the wire is OK, check/replace Oil Pressure Switch Resistor (see schematic). If resistor is OK, remove the Instrument Cluster and inspect the printed circuit for a short to ground. If OK, service the Instrument Cluster (see Section 8C).

G: OIL PRESSURE GAUGE SHOWS NORMAL PRESSURE WITH THE IGNITION SWITCH IN RUN (ENGINE NOT RUNNING)

Connect: FUSED JUMPER

At: FUEL PUMP/OIL PRESSURE SWITCH CONNECTOR (Disconnected)

Condition:

Ignition Switch: RUN

Jumper Correct Between Result For Diagnosis ------- ------- -------------

TAN & Ground Gauge indicates (see schematic) low oil See 1 pressure

. If the result is correct, check for a poor connection. If OK, replace the Fuel Pump/Oil Pressure Switch.

1. Check/repair TAN (31) wire for an open between S110 and the Fuel Pump/Oil Pressure Switch (see schematic).

H. OIL PRESSURE GAUGE INDICATES HIGH WITH THE IGNITION SWITCH IN RUN

. If engine is not running, check the TAN (3 1) wire for an open between SIIO and terminal C3 of the Instrument Cluster. If OK, service the Instrument Cluster (see Section 8C).

. If the gauge indicates high when the engine is running, check the TAN (3 1) wire for an open between S110 and terminal C3 of the Instrument Cluster. If OK, check the Oil Pressure Switch Resistor and BLK (150) wire for an open. If OK, service the Instrument Cluster.

OIL PRESSURE GAUGE

The engine oil pressure is displayed by the OIL Pressure Gauge. The pointer of the gauge is moved by two coils, and its operation is similar to that of the Fuel Gauge.

The Fuel Pump/Oil Pressure Switch and Oil Pressure Switch Resistor are connected to the junction of the two coils. The Fuel Pump/Oil Pressure Switch closes at 0-5 psi providing a low resistance ground path for the OIL Pressure Switch. When the Fuel Pump/Oil Pressure Switch is closed, the OIL Pressure Gauge pointer is at 0 psi. After the engine is started and normal oil pressure builds up, the switch opens. The Oil Pressure Switch Resistor then provides a preset high resistance (68 ohms) ground path for the gauge. This change in resistance moves the pointer on the gauge.

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.