AFIT Adapter Cable Identification and Vehicle Application Chart

The Active Fuel Injector Tester (AFIT) Diagnostic Kit, essential tool CH-47976 (Fig. 7), is designed to test fuel injectors on port and direct injected engines going back to the 1996 model year. As new vehicle applications have been introduced, the kit has grown to include a number of available adapter cables, including for SIDI engine fuel systems (Fig. 8A) and the Duramax diesel engine. (Fig. 8B)


TIP: The AFIT Kit, CH-47976, was an essential tool for Tier 1, 2, 3, and 4 dealerships only. Tier 5 dealerships may order the tool at



Fig. 7 – CH-47976 


Fig. 8A – CH-47976-500A 



Fig. 8B – CH-47976-505 


An AFIT Vehicle Application Chart has been developed to help identify the correct cable adapters for each GM model.


The chart lists the model applications, engine RPO, cable components, type of communication, SENT (Single Edge Nibble Transmission) applications and Stop/Start applications.


Correct Connections


When testing an engine using the AFIT kit, do not connect the adapter cables to the vehicle until instructed to by the AFIT MCU (Main Control Unit). The MCU should be placed in the vehicle cab and plugged into the power adapter.


The DMU (Drive & Measurement Unit) should be placed in the engine compartment and connected to the vehicle’s 12-volt battery and to the MCU.


Select a vehicle on the AFIT MCU and then select an injector test. Follow the on-screen instructions/prompts on the MCU to connect to the vehicle. When prompted, with the ignition off, connect the DMU cable to the vehicle ECM harness connectors.


TIP: To help in determining which adapter to use, the AFIT will display the correct adapter during the testing process. The latest software must be used in order to display all correct adapter and cable selections.


Software Updates


Download the latest AFIT software through the Service Workbench selection of “Essential Tools – Software Updates” in GM GlobalConnect (U.S. only).


In Canada, GlobalConnect provides a Quick Link titled “Essential Tools – Software Updates” available from the Service page.


– Thanks to Chuck Berecz


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