What this page does
The Honda AP1 S2000 coolant gauge function lets a Nexus ECU drive the S2000's factory temperature gauge. This wiring page tells the ECU which output is connected to the gauge and which polarity to use. If you're on a Nexus S2 or Nexus S3 S2000 plug-n-play kit, check the adaptor harness guide for which pin the gauge uses, and still confirm the settings below.
The two settings
- Coolant Gauge Output: choose a free output for the gauge signal. That's normally a DPO (Digital Pulsed Output) or a stepper output. Pick one that isn't already assigned to another function.
- Active State: sets the output's polarity. With Low, the default, the ECU switches the wire to ground when the output is on. High reverses that, so the wire is grounded while the output is off and released when it's on.
Leave Active State at Low unless you have a specific reason to change it. If the gauge doesn't move, or its reading makes no sense against the coolant temperature shown in NSP, the output choice and polarity are the first things we check, followed by the pin in the connector.
Elite owners should use the Elite version of this function.
