Without Scan Tool

Switching On Board Diagnostic Test Modes

How To Switch On-Board Diagnostic Test Modes (Without Consult):

How To Switch On-Board Diagnostic Test Modes (cont):

Note: Switching modes while the engine is running is not possible. When ignition switch is turned off during diagnosis in each mode, and then turned back on again after power to the ECM has dropped off completely, the diagnosis mode will automatically return to On-board Diagnostic Test Mode I but stored codes will remain in memory unless the erasing procedure has been performed.