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When you say they cant scan it, does this mean there scan tool will no communicate with the data link connector, if so have you check the fuse to see if its blown and ther eis no power at the DLC?
the CEL is on, the over drive light is flashing, the service charging system light is on no one has been able to scan the vehicle had it to 3 diffrent shops nobody wants to mess with it need help
Check these 2 tests to see if they pass.