The only indicator still working on the gauge is “water level”. The pump wouldn’t switch on. HFS3.

[iideaiidea]

I’ve been using HFS3 for a couple years and it’s been working without
any problems. Then I haven’t used the system for some time. Now when
trying to turn the system on, no backlights or flow sensor display
switch on, the only light still working is "water level".

The controller is connected correctly, there is a fuel injection load
indication. When closing with a “sys” jumper, the lamps on the
controller switch on and the flow control valve triggers, but the pump
still does not turn on. The pump is undamaged, I tested all the
connectors and wires, they are also fault-free.

A small note. When inserting the flat cable connector of the gauge
slowly and carefully, it briefly lights up the backlight and the flow
sensor display. When the connector is fully inserted, the only
indicator working is "water level".

What can I do? Can you help?

[Richard L]

1. Check the tank level
2. Unplug the water level sensor and see if the system starts

LMK

[iideaiidea]

It did not help.

[Richard L]

Can you post a picture of the controller (with all cable plugged in) and a picture of the gauge.

[iideaiidea]

https://yadi.sk/i/_RguXaNPtZhgV

[Richard L]

OK, all is good. Unplug the blue harness and let me what happens.

[iideaiidea]

https://yadi.sk/i/HuZorzoZtZipc

[Richard L]

Weird. I have not seen this before.

Do you have a digital multimeter?

[Richard L]

One more test.

Unplug the gauge and let me know if the pump comes on with "SYS" test

[iideaiidea]

Yes, of course.