Scan Tool Will Not Communicate With Class 1 (UART) Data Line

Refer to flowchart. See Fig 1 and Fig 2 .

Fig 1: Scan Tool Will Not Communicate With Class 1 Data Line (UART) Diagnostic Flowchart (1 Of 2)

Courtesy of GENERAL MOTORS CORP.

Fig 2: Scan Tool Will Not Communicate With Class 1 Data Line (UART) Diagnostic Flowchart (2 Of 2)

Courtesy of GENERAL MOTORS CORP.