OUTPUT SWITCHING MODULES (OSMs): Notes

WARNING: This page is about a different car, the 1992 Cadillac Allante and 1991 Cadillac Allante. However, it is still accessible from the selected car via links, so may be relevant.

Each OSM is a solid state switching device that consists of:

Four outputs to power lamps
Address pins that will uniquely identify the OSM when connected to the vehicle harness
Two data line inputs that are used to communicate with the BCM
A power and ground connection

Based on the commands the OSM receives from the BCM, the OSM will turn on and off its outputs, which results in the headlamp, tail lamp, turn signal lamp, or courtesy lamp operation required under the particular operation condition. For a detailed general and specific bulbs, addresses, power and ground for each OSM, refer to illustrations. See Fig 1 and Figure .

Fig 1: Identifying Typical Output Switching Module & Wiring

Courtesy of GENERAL MOTORS CORP.