G4 Wiring and Installation Manual
40
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Low Side Driving a Solenoid
8.3.2
High Side Driving (Switching Power Supply)
Some single terminal solenoids are grounded through the engine block (e.g. most Honda
VTEC solenoids). Therefore power must be applied to the terminal on the solenoid to turn it
on. Auxiliary Outputs 5 to 8 can be used to supply power to a solenoid. If Auxiliary Outputs
5 to 8 are already used then it will be necessary to wire a relay to control the solenoids
power supply.
Aux 5 to 8 high side drivers can supply up to 0.5 Amps. this means the solenoid must have
a resistance greater than 30 Ohms.
High Side Driving a Solenoid
8.3.3
Switching Through a Relay
To switch any large load through a relay, the wiring shown below should be used. Examples
of such loads include fuel pumps, engine coolant fans and air conditioning compressor
clutches. DO NOT wire high current devices directly to the ECU.