vtec solenoid wiring haltech elite 1500

hi guys,

just want to get some clarification on something. I have to wire a honda b18c engine using a haltech elite 1500 ecu. do i wire the vtec solenoid using a relay (like how link suggests) or could i wire it directly using one of the stepper 1/DPO outputs (eg pin 31A)?

A relay isn't required, but check the polarity -- I believe the the Honda OEM harness grounds one side and the OE ECU switches the high-side. Most aftermarket ECU's want to control the ground-side (ie, solenoid connects to ignition power in the harness). That may be why a relay is suggested (to invert the control of the solenoid if adapting the OEM harness).

WOW! thanks for the quick reply David.

i understand what you are saying. the wiring diagram says it could output either Battery Voltage or ground so with that and your explanation i shouldn't need the relay. thanks for your assistance David.

Connect it to one of the stepper outputs and high side drive it.