CAN Bus Setup: ECU and Flock Gauge

CAN bus lets your Flock gauge display readings that your ECU already measures. Setup has two parts: configure the ECU to transmit the correct data stream, then choose the matching ECU preset and readings on the gauge.

This guide covers the five presets in the gauge: Link, Haltech, ECUMaster, MaxxECU and Hondata. Compatibility depends on the ECU model, firmware and output protocol. A brand name alone does not guarantee compatibility with every ECU from that manufacturer.

Choose your ECU

Select your ECU below for its software settings, wiring and gauge setup. Each guide includes screenshots of the gauge setup screens.

LinkLinkView setup guide → HaltechHaltechView setup guide → ECUMasterECUMasterView setup guide → MaxxECUMaxxECUView setup guide → HondataHondataView setup guide →

Shared CAN bus and gauge setup

The steps below cover the hardware and gauge settings shared by all five ECU presets. Follow your ECU guide above to configure its CAN output.

What you need

  • A Flock gauge with CAN-capable firmware and the matching SD-card web interface. If the CAN setup screens below are missing, follow Updating Your Gauge.
  • A Flock CANbus adapter and its supplied gauge connection harness.
  • Access to the ECU’s CAN High, CAN Low and ground connections, using its model-specific wiring diagram.
  • A twisted pair for CAN High and CAN Low, with suitable CAN bus termination.
  • A laptop with the ECU manufacturer’s tuning software and connection cable, plus a phone or computer for the gauge’s WiFi setup.

The ECU must have the sensors you want to display installed, enabled and calibrated. Selecting OilPressure on the gauge does not add an oil-pressure sensor to the ECU.

1. Connect the Flock CANbus adapter and ECU

Turn power off before wiring. Connect the Flock CANbus adapter to the gauge’s five-pin expansion connector using its supplied harness.

Connect ECU CAN H → Flock CANbus adapter CAN H, ECU CAN L → Flock CANbus adapter CAN L, and the adapter’s ground connection to a common ground with the ECU. Follow the connection labels and wiring instructions supplied with the Flock CANbus adapter. Use the same ECU CAN channel you will configure in software.

CAN H and CAN L connect to the Flock CANbus adapter’s ECU-side connections. Do not connect ECU CAN H or CAN L directly to the gauge’s expansion pins. Keep the gauge powered through its normal power connector.

Use a bus layout with short branches and a 120Ω terminator at each end. Check the ECU’s and Flock CANbus adapter’s termination configuration before adding resistors. With an unpowered bus and both terminators connected, resistance across CAN H and CAN L is normally about 60Ω. Confirm your ECU’s termination behavior in its manual.

2. Set up your ECU software

Back up your calibration before changing CAN settings. All devices on one bus must use the same bit rate. If your existing bus uses a different speed, use an available separate CAN channel or a properly reviewed custom configuration.

Gauge preset ECU output to use Bit rate IDs expected by the preset
Link Generic Dash / DisplayLink 1 Mbit/s 1000 decimal / 0x3E8
Haltech Haltech CAN V2 / broadcast dash stream 1 Mbit/s 0x360, 0x361, 0x368, 0x372, 0x3E0
ECUMaster EMU standard CAN stream 1 Mbit/s Base 0x600; preset uses 0x600, 0x602, 0x603, 0x604
MaxxECU MaxxECU Default 1.3 500 kbit/s 0x520, 0x530, 0x536, 0x537; offset 0
Hondata KPro4 Hondata / MoTeC CAN stream 500 kbit/s 0x660, 0x661, 0x662

These presets use standard 11-bit CAN identifiers. The gauge loads the bit rate from the preset automatically.

3. Set up the Flock gauge

  1. Power the gauge. For a new gauge, connect to Flock Setup. For an existing gauge, enter Settings Mode and join the WiFi network shown on its screen.
  2. Scan the gauge’s QR code. If needed, open http://192.168.4.1/setup.html for initial setup or http://192.168.4.1/settings.html for settings. Stay connected if your phone reports that this WiFi has no internet.
  3. In initial setup, tap Get Started, select the five-pin expansion connector in the port diagram, then choose CAN bus. In Settings, edit an available display slot and select sensor type CanBus.
  4. Choose your ECU brand. The gauge loads its signal library.

Flock ECU selection at 375px phone width

ECU preset selection in the gauge web interface. Screenshot from a local preview; the displayed current value is simulated.

  1. Tap the signal you want to display, such as EngineSpeed or CoolantTemp. Use Search signals to find it.
  2. Set a descriptive label, digital display options and warning thresholds where available, then tap Save.
  3. Add more readings in the remaining display slots, selecting a different signal from the same library. The gauge supports up to four display slots; these CAN assignments do not mean four separate CAN cables.
  4. Finish setup or return to the gauge display. If the interface requests a restart, follow that prompt.

Flock Link CAN signal picker at 375px phone width

The Link library’s signal picker. Other presets show their own available channels. Screenshot from a local preview; the displayed current value is simulated.

One CAN library is shared across the gauge. Adding another reading uses that library. Use the CAN library’s Replace control when changing ECU/protocol. Replacement affects every CAN display slot: choose signals again if their names no longer match.

Preset numbers use the decoded protocol units. Do not assume a general temperature or pressure preference converts a custom CAN value. Compare against the ECU software in the same units before setting warnings. MAP is absolute manifold pressure; it is not automatically boost pressure relative to atmosphere.

4. Check the readings

With the car stationary, compare gauge readings against the ECU software. Start with RPM and coolant temperature. Check throttle position and battery voltage, then pressures and other channels. Account for the gauge’s display rounding. Set warnings only after you confirm the values and units.

The presets expose a subset of each ECU’s stream. A listed channel still depends on the ECU’s sensors and firmware. Below-zero temperatures deserve an explicit comparison: signed-field handling varies between the supplied presets. In the currently reviewed ECUMaster preset, coolant temperature is not marked signed and oil temperature is marked signed; in the MaxxECU preset, temperature fields are not marked signed. Contact Flock for a corrected configuration if those ranges are needed. A zero or frozen value alone does not prove that CAN communication is working.

Troubleshooting

What you see What to check
No CAN option or ECU picker Update both gauge firmware and SD-card interface using the Flock update guide.
All readings missing, zero or frozen ECU powered; stream enabled and saved; correct CAN channel; matching bit rate; CAN H/L polarity; Flock CANbus adapter connections and common ground; gauge harness connection; termination.
One channel missing Sensor enabled/calibrated in the ECU, channel present in this preset, ECU firmware supplies that message, and selected signal name matches the installed library.
Numbers are wrong Correct protocol, message IDs, byte order, scaling, signed fields and units. MAP and boost are different measurements.
Data stopped after changing libraries Reassign every CAN display slot to a signal in the new library and follow any restart prompt.
A different ECU or custom stream Select other to upload a compatible Flock CAN JSON file or create one signal. A DBC file needs conversion; renaming it to JSON is insufficient.

If you need help, send hello@flock-mfg.com your ECU model, ECU software/firmware version, gauge firmware version, Flock CANbus adapter connection details, CAN speed and screenshots of your ECU CAN settings and gauge signal selection.

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