Diagnostic Aids

Check resistance of each ECM controlled relay or solenoid before replacing ECM. See CONTROL UNIT  under COMPUTERIZED ENGINE CONTROLS. Replace any relay or solenoid that measures less than 20 ohms.

Fig 1: A/C Clutch Circuit Schematic (4.3L Turbo PFI)

Courtesy of GENERAL MOTORS CORP.

Fig 2: A/C Clutch System Flow Chart (4.3L Turbo PFI) (2 Of 2)

Courtesy of GENERAL MOTORS CORP.