External Safety Path
The external safety path circuit is maintained to ensure that the decel fuel cutoff is activated if a fault occurs with the output control of the throttle motors causing the engine not to return to idle.
The external safety path exists from the electronic brake light switch, through the 4° switch, to the decel fuel cutoff inputs of the ECM control modules.
With the accelerator pedal released (4° switch closed) and the brake pedal pressed, a high signal is supplied (bypassing the EML control module) to the DME control modules to activate decel fuel cutoff.
A special tool is not required to test the safety path circuit for proper operation. A procedure is listed in the diagnostic pages for this purpose.
It requires stepping on the accelerator 4° but far enough to display an off idle condition. With this displayed on the DIS/MoDIC screen, stepping on the brake pedal will display the decel fuel cut off request to the ECM.