Chart D, Serial Data Circuit Open (CRT Equipped)

Serial data line is redundant to most devices with which it communicates. Only one line need be connected to each device for system to function. When making repairs, both lines should be made operational. If system shuts down when ALDL cover is removed, a single open existed before. Now a second open in circuit is being created by removing ALDL cover.

1. This test and all subsequent tests are designed to subdivide data line. This is necessary to pinpoint location of open in data line. This is not only way to pinpoint an open, but is quickest path to finding open in this case.

Fig 1: Chart D, Schematic, Serial Data Ckt Open (CRT Equipped)

Courtesy of GENERAL MOTORS CORP.

Fig 2: Flow Chart D, Serial Data Ckt Open (CRT Equipped)

Courtesy of GENERAL MOTORS CORP.