How the ECU controls the starter
A starter motor can draw hundreds of amps, so nothing from the ECU goes to the motor itself. The ECU only switches the starter solenoid, which in turn closes the heavy contacts that feed the motor. The Starter Motor wiring node is where you tell the ECU which output does that job.
Output choices
| Output type | Connects to | Notes |
|---|---|---|
| High Current Output (HCO), 25 A or 8 A | Starter solenoid directly | The simplest option where you have one free |
| Half Bridge Output (HBO) | Starter solenoid directly | Also strong enough to drive the solenoid without a relay |
| Digital Pulsed Output (DPO) | A relay, which then drives the solenoid | Too light for the solenoid on its own |
| Spare injector or ignition output | A relay, which then drives the solenoid | Handy when the other output types are all used |
In NSP, click Edit to assign an available output as the Starter Motor Relay Output, or Clear to remove the assignment.
Check the solenoid's current draw against the output you're using, fuse the feed, and test the output from the software with the engine safe to turn over. If you use a relay, a proper 30 A automotive relay is the usual choice. See how relays work if you're wiring one for the first time.
The logic that decides when the starter is allowed to run is set up in Starter Motor. Many builds also let the ECU handle the main power with an engine control relay.
