Running electric fan with FIdle port

[vtmegasquirter]

I'm running MS2 v3 board. I followed the instructions for using the FIdle port to control my fan, but it's not working. The port indicator is lighting up when the criteria is met, coolant>180 and RPM > 450. hysteria =10 on both. Power on =0 and trigger value = 1. I guess I'm confused as to whether I should see a 12v signal going to my relay or a ground. I checked it with my multimeter and couldn't confirm either. Got to be something simple, so any help or suggestions would be appreciated.

[Matt Cramer]

You should see a ground on pin 30 when it is on.

[vtmegasquirter]

OK, I'm not seeing a ground when I check the FIdle output from my relay board. Tunerstudio indicates the the port is on. Is there anything on the relay board to check?
Thanks

['66fb]

The signal on relay board input pin #30 will be a "logic level" ground...about 0.7 vdc IIRC. It will swing between battery voltage (when off) to near ground when on.

I removed the FIDLE relay from the board and jumped relay socket pin #2 to pin #4 then used the signal at pin #6 of the 20 pin strip on the relay board to control a high current relay for the fan.

[vtmegasquirter]

Thanks for the tip. Just makes me wonder why this link for port configuration: http://www.megamanual.com/ms2/spare.htm , states the following.


Example: Electric Cooling Fan Control

Another example is electric electric cooling fan control. We will turn it on 180°F and off at 170°F, using the relay board FIdle output to control a separate cooling fan relay (the traces on the relay board may not have enough current capacity to control your fan directly):


FIdle (PM2)
Port PM2, FIdle enabled
variable = coolant > threshold = 180, hysteresis = 10,
AND
variable = rpm > threshold = 450, hysteresis = 10, (fan will not run while cranking - you can add any second condition that works for you, of course)
Power-on value = 0
Trigger value = 1

Maybe I missed something here?

[Matt Cramer]

Note that if you have the relay in place on the relay board, it may be supplying power to the FIDLE pin and not ground.

[vtmegasquirter]

Actually, I was getting approximately .7 v, I was expecting 12v to trigger my fan relay. Matt, do you see any issue with the suggestion to remove the relay and jump it as discribed above.

[Matt Cramer]

Actually, I was getting approximately .7 v, I was expecting 12v to trigger my fan relay. Matt, do you see any issue with the suggestion to remove the relay and jump it as discribed above.

No, that should work fine.

['66fb]

Actually, I was getting approximately .7 v, I was expecting 12v to trigger my fan relay. Matt, do you see any issue with the suggestion to remove the relay and jump it as discribed above.

To clarify my earlier post a bit, after the jumper is installed in lieu of the FIDLE relay on the relay board a wire must be connected from pin #6 (of the 20 pin terminal block) to one end of the coil on your external relay -the other side of the coil on this relay must be connected to 12v.

To protect the driver transistor on the MS board from voltage spikes a diode should be installed across the external relay coil. The banded end of the diode (suggest 1N4000) must be connected to the positive supply side of the relay coil.

The megamanual shows this for driving spare outputs, if you substitute pin #6 of the 20 pin term block for the point labeled "C" then you are adding all the circuitry to the right.

http://www.megamanual.com/ms2/spare.htm

[vtmegasquirter]

Thank you for the clarification. Much apreciated