How The One Touch Starting System Circuit Works

One Touch Starting Power Control

How the Circuit Works

The One Touch Starting system sends the ignition switch start input to the PCM. When the PCM sees this signal, it engages two cut relays to energize the starter motor.

The PCM keeps the starter motor engaged until:
1) The engine starts.
or
2) The starter has run for several seconds, but he engine did not start. (actual crank time varies with temperature).

To provide redundancy, the starter circuit includes two cut relays between the PCM and starter. Both relays must close before the starter engages.

Once engaged, the starter remains on even if the ignition switch returns to position II (ON). To reduce overall electrical load, the IG2 (Hot in ON) and accessory (ACC) power circuits both include a circuit cut relay. These relays are normally closed, but open while the starter is engaged. If either cut relay fails, the engine starts but some vehicle electrical systems or accessories will not receive power.