The TCU controls the power to the solenoids via the power relay circuit. This relay also acts as a safety cutout in case of engine stalls. When there is a RPM or Speed signal, the TCU will switch the relay output on. In case of an accident this relay will be shut down in one second after the engine and speed has died. This will stop power from making sparks during shorts to eliminate a fire. Note: Do not connect solenoid power with ignition coils or injectors as they will feed back power after the ECU is switched off. This may damage the solenoid drivers. They must be connected to the TCU power relay.
Mechanical Relays
Pin 86 of the Relay is tied to battery positive.
Leave A Comment?
You must be logged in to post a comment.