Fan Indicator Light Circuit Review

[Jim Doak]

Does this circuit look correct for wiring an indicator light when I manually trigger the fan with a dash mounted toggle switch?

I'm assuming that the Ron Francis dark green thermo wire is used to energize the fan by grounding the relay.

Thanks.

[F500guy]

So that will not work, there will be a ground at both sides of the light. You need to determine if you want the light to show 1) the switch is activated or 2) any time the fan runs. What your are trying to do is kind of a mute point, it will not be very help full to show that you have turned the manual switch on. You may be better of having a light that shows the fan should be running, weather you use the switch or not. If you want to just show that the switch is operating, you would best off with a 2 pole switch, 1 pole for the fan relay "on" function and a second pole that has 12v supply that is fused and would then switch on the led with the switch.

[Jim Doak]

I just want the light to indicate when I manually operate the fan with the toggle switch.

[F500guy]

Something like this if you just want the light to show when the switch is active.
210323

[Jim Doak]

Thanks, F500guy.

So, it looks like I need to replace my SPST toggle with a DPST switch?

Also, for the 12 volt supply; could I use one of the unused wires in my RF harness, such as the gray wire used for the non-existent oil temperature gauge?

Edit: After looking at the wiring diagrams, I'm not sure if I should use one of the unused gauge sender wires.

What do the electrical gurus think the best way would be to provide a switched 12 volt supply to the DPST switch for a manual fan illumination light? Would it be OK to use one of the unused gauge sender/sensor wires?

[weendoggy]

Not knowing the RF wiring, but it's simple electrics. Using the DPST is the easiest way to go and all you need to power the light is a 12v source wire (I'd choose a 12v ignition on one) and if the gray wire is HOT when key on, use it. More importantly is how the fan relay is operating. If done with a negative ground sensor trigger, all you need to do is wire the one side of the DPST to that pole and 12v to the other pole for the light.

[Jim Doak]

Thanks, Glenn.

I think we're on the same page.

1. Use a DPST switch.

2. One pole will use the Ron Francis Dark Green Fan Sensor wire (fan relay negative ground) on one side and a ground on the other side.

3. The other pole will use a 12 volt switched source on one side of the switch; the other terminal will be wired to the indicator light, then from the light to a ground.

[F500guy]

The radio wire from the RF harness, just use a 18 g wire if the fuse is 10 amp, or change the fuse to smaller if that is the only feed off the fuse.