First if all, I do have many years of experience with cars, rebuilding, fixing tuning and have electronics degree. So pretty technical. But need some input from those with Honda experience...

ABS light on and owner had a sensor replaced. But still on, so I said I'd take a look.

Did the brake pedal, ignition thing to reset the DTC. ABS light duly flashed twice to indicate reset. But immediately came back permanently on, without flashing a DTC.

Followed the Honda Service manual troubleshooting, but they end up saying to replace the ABS indicator gauge circuitry. Which is clearly nonsense as the ABS indicator does turn on and off under the control of the ABS module when you reset it.

All connections, voltages etc. appear good. (Except Sensor resistance, which are all open circuit, measured at the sensor. But that may be another issue for later, shouldn't affect us here?? As would not expect the ABS control to expect a sensor signal until vehicle moving)

What would cause an ABS control unit, to pulse to say it'd reset the DTC, then show a permanent on, with no pulsed DTC code?

U/S control unit, or is there something else I've missed within the Honda service manual.