Indicator Does Not Light With Ignition On, Engine Off

1. Disconnect oil pressure indicator switch. Connect fused jumper wire between oil pressure indicator switch and ground. Turn ignition on. If indicator illuminates, check for poor connections of oil pressure switch connector. Repair as necessary. If connections are okay, replace oil pressure switch.
2. If oil pressure indicator does not illuminate, check oil pressure circuit for an open, poor connection and open oil pressure indicator bulb. Repair as necessary. If circuit is okay, replace instrument panel.

Fig 1: Identifying Terminals Of Instrument Cluster Connector

Courtesy of GENERAL MOTORS CORP.