Bypass Circuit

Ignition System Wiring.:

OPERATION
The PCM/EC enables the EST mode by switching the bypass line high. When the bypass line is low the DIS module controls secondary coil firing. To enable the EST the PCM/EC applies 5 volts on the bypass line (at approximately 400 RPM) indicating EST mode to the DIS module. In EST mode the DIS module uses the EST signal from the PCM/EC to fire the secondary coils. The PCM/EC has internal feedback to monitor the state of the bypass line.





BYPASS MODE
BYPASS mode is defined as any time during engine operation that the EST signal is not controlling ignition spark timing. The BYPASS line is held low by the PCM and the EST line is held low by the DIS module. The BYPASS mode ignition timing shall be determined by the DIS module.