1981 Spider fuse block question

[Roycape]

Hi all - I have a 1981 Spider that I am updating the electrical. I have done the headlamp relay conversion already but I'd like to: a) add a new circuit through a relay to run a 12 V accessory and b) I'd like to power the heater fan through a relay.

I don't have power windows and in the fuse block for fuses M and N (Left and Right Power windows), there are 2 wired terminals at the back of each fuse with one unused terminal. My question is can I use either of the unused terminals of these fuses as a trigger to the relays. In other words, would this be a power source that I can use when the car is turned on?

For the heater fan, I know I can use the brown wire that provides power to the heater switch as the trigger to the relay but was just wondering about the unused terminals at the back of the fuse box.

The reason I'm asking is that I'm restoring the car with the battery out and a lot of the wiring disconnected and I'm not sure how to test for connectivity with no power.

Any assistance would be appreciated. Thanks.

[rlux4]

Without power you'd have to check for conductivity. You'd need to add a long enough length of wire to one of the probes to reach the other end of a circuit. I use a length of wire alligator clipped to the probe.
Hope I understood your question correctly.
Ron

[vandor]

>I don't have power windows and in the fuse block for fuses M and N (Left and Right Power windows), there are 2 wired >terminals at the back of each fuse with one unused terminal. My question is can I use either of the unused terminals of >these fuses as a trigger to the relays. In other words, would this be a power source that I can use when the car is turned on?

I don't see why not. I think the wires to the door are present, I would disconnect those just to be safe.

[spider2081]

Keep in mind the power window fuses are not fed directly from the ignition switch. The ignition switch powers the power window relay located under the glove box. The relay is energized in "start" and "run" positions of the ignition switch. The energized relay connects "hot all the time" power from C17 a 4 terminal block under the instrument near steering column to the power window fuses. So the fuses have power in "start" and "run" as you wish but you will have a problem trying to trace it with a meter with the battery out of the car.
A black wire from C17 feeds the relay movable contact and a pink wire from the relay feeds fuses 11 & 12 when the relay is energized.
Hope this helps

[Roycape]

Thanks all for your input. I see the pink wire going to fuses M and N (11 and 12) and the red and orange wires coming out to the left and right power window switches. That being the case, then the unused terminals by these fuses should have power. The wiring in this vehicle is excellent and the POs didn't butcher anything so I am assuming that everything should work since the power window relay is present under the glove compartment.

The other question I thought about is using a relay(s) to power the heater blower motor. Since the heater motor switch has a "Hi" and "Lo" setting, do I need to run 2 relays? One for the "Hi" setting and one for the "Low" setting? Should the triggers for these relays come AFTER the switch? If the trigger to the relay is BEFORE the switch then I will only need one relay. I didn't know if that would work since the switch has 2 settings

Again any input would be appreciated.