Computers & Controls - Tech 1 Diagnostics

91chevy03

GMC NUMBER: 91-6E-49


GROUP: 6E Engine Emissions


DATE: December, 1990


CORPORATE


NUMBER: 066504


SUBJECT: TECH 1 DIAGNOSTICS FOR TURBOCHARGED 4.3L ENGINE


MODELS: 1991 GMC T PICKUP (SYCLONE)


The 1987-91 TECH 1 Cartridge (P/N TK02050C) contains the diagnostic information required for the 1991 GMC Syclone equipped with the 4.3L turbocharged engine. Diagnostics can be accessed either by selecting the VIN engine code or by selecting the appropriate fuel control system.





To access diagnostics, enter the appropriate model year when the following screen is displayed:





To enter diagnostics via VIN engine code, press the "FO" key for VIN when the following screen is displayed:


Vehicles equipped with the 4.3L turbocharged Port Fuel Injection (PFI) engine will have the same engine code (Z) in the eighth position ot the VIN as other 4.3L Throttle Body Injection (TBI) engines. As a result of the differences between the two fuel control systems, a specific ECM is required for the turbocharged engine. In order to properly establish


communications between the TECH 1 and this "specific" ECM, a special VIN character "S" needs to be entered.





When the following screen is displayed, advance the "Flashing" VIN character by pressing the "NO" key or the "ARROW" keys until the VIN letter "S" flashes. Then press the "YES" key.





To enter diagnostics via the fuel control system, press the "F1" key for Port Fuel Injection (PFI) when the following screen is displayed:





Advance the TECH 1 fuel control system screens by pressing the "NO" key until the following screen is displayed. Then press the "YES" key.