Hondata

I am doing some trouble-shooting on my idle and want to rule out any wiring issue. When my radiator fan activates (air-con off), the FANC should come on and ELD volts should go down, is that right? If the FANC does come on but the radiator is on that means the ECT switch is turning it on right? DO I need to worry about this?

If the ELD load doesn't go down when the radiator fan comes on that will affect idle and recovery to target idle rpm, is that right?

Wiring is a 96-98 Civic Obd2a. Got custom radiator fan relay cause the stock one burnt out. I suspect is not correctly wired. How do i test this?

To check the wiring I suggest you look at the Helms ETM for your year of vehicle.

Change or disable the FANC output so that it does not come on, and make sure your Thermo switch is able to turn on the fan.

OK, will study the HELMs, but that's a good idea to disconnect the FANC and see if the ECT Switch activates the Fan. Likewise, i will disconenct the ECT switch and see if the FANC turns-on the fan.

OK fugured it out.

Connect relay terminal 87 to the vehicle body or battery negative terminal. Use a piece of 18-gauge primary wire with a solder-less female spade connector on one end, and a solder-less ring terminal on the other.

Connect relay terminal 85 to an automotive circuit breaker (fuse).

Civic 96-98 note; the order of the connection will be (a) The battery positive terminal (b) ELD (c) Fuse (d) Relay terminal 85.

Connect the circuit breaker's other terminal to the battery's positive terminal. Use primary wire that's large enough to handle the current load of the new device.

Just one more question, if the fan is activated by ECT switch and not FANC output, FANC will show "off" in the Hondata sensor list, is that right?



Connect relay terminal 86 to the device that needs power. Use the same gauge wire as that used for terminal 85.

Run an 18-gauge primary wire to a switch in the driver's area. Power the switch from a fused circuit inside the vehicle (FANC output – pin A27 ECU OBD2A). Connect the wire to relay terminal 30 with a solder-less connector

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FANC is an output, so will only show on when the ECU is commanding the FANC on, not when the ECT switch is grounding to turn on the fan/s.

AFAIK, my USDM OBD I P72 does not use the FANC for anything. It does not use it to turn on the fans for temp (ECT switch grounds) nor the A/C (grounds through the A/C and fan switch).

I disconnected the ECT switch once and let the factory temp gauge get far higher than stock, and it did not turn on the fans. I do not know the actual temp. I was more limited with my tools back then.

kelly wrote:FANC is an output, so will only show on when the ECU is commanding the FANC on, not when the ECT switch is grounding to turn on the fan/s.

AFAIK, my USDM OBD I P72 does not use the FANC for anything. It does not use it to turn on the fans for temp (ECT switch grounds) nor the A/C (grounds through the A/C and fan switch).

I disconnected the ECT switch once and let the factory temp gauge get far higher than stock, and it did not turn on the fans. I do not know the actual temp. I was more limited with my tools back then.

I think FANC is a ground, like the ECT switch. The radiator fan relay (coil) is activated by with the ECT switch or the FANC. Both are recieveing power from Fuse 17 (7.5 Amps) thru the junction connector C130 below the dash.

Yes, the FANC is a ground. I didn't look at the schematic.