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Home >> Volvo >> 1992 >> 740 GL, AW70 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Self-Diagnostic Systems >> Fuel Injection, Ignition & Turbo Systems
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Fuel Injection, Ignition & Turbo Systems

Fuel injection, ignition and turbo systems each feature a self-diagnostic function for fault tracing. A common diagnostic unit for retrieving codes is located in engine compartment, behind left strut assembly. Diagnostic unit is equipped with an LED indicator, activation button and function select cable. See Fig 1 .

Fig 1: Identifying Diagnostic Unit
G121540Courtesy of VOLVO CARS OF NORTH AMERICA.

Diagnostic unit output socket No. 2 is used for fuel injection. Socket No. 6 is used for ignition system. Socket No. 5 is used for turbo system. Once selector cable has been inserted in correct slot, depressing button once, twice or 3 times selects from one of 3 control (fault tracing) functions. Faults stored in ECU memory are read by observing LED flashes.

Diagnostic system for fuel injection ECU stores 17 fault codes, ignition ECU stores 9 fault codes, and turbo ECU (if equipped) stores 8 fault codes. All fault codes contain 3 digits (example: 4-1-3). Since all codes have 3 digits, each code requires 3 series of flashes. A 3-second interval separates each series of flashes.