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Home >> Cadillac >> 1991 >> Allante F7/ME9 >> Repair and Diagnosis >> External Pages >> Different car >> Section 55 (Body Computer Module) >> Description & Operation >> Lighting System >> Communication
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Lighting System: Communication

WARNING: This page is about a different car, the 1990 Cadillac Allante. However, it is still accessible from the selected car via links, so may be relevant.

The communication between the nine OSM's, the BCM, and the Left Switch Pod is achieved via the lighting data line. The BCM will continuously scan from the Left Switch Pod to each of the nine OSM's one at a time, making commands to each, and requesting information from each. The data line is designed as a complete loop so that each element on the data circuit has two data circuit inputs. This loop design will allow the circuit to operate with one open in the circuit. Fig 1 details the data circuit.

Fig 1: Lighting System Data Line Circuit
G00097079Courtesy of GENERAL MOTORS CORP.