Use of a toggle switch

[Toploader]

Before I start cutting wires.....................upon hooking up my rear defog sw on the '86 MGM, the battery this morning was stone dead after about one week.
I want to just forget about this factory defog switch, and in its place utilize a generic toggle switch. Can you offer suggestions as to wire the toggle switch after I have cut off the defog wires from the connector?
Many thanks in advance.

[sly]

First, the switch should be rated the same or higher than the fuse (I think that should be 40A - that's the rating of the one on the 93). Also, that circuit has power at all times but uses the RUN circuit to latch the built in relay that switches the power and turns on the LED indicator. So yes, you can replace with a hard switch, but you will have to remember to turn it off as the main power is from the battery directly. If you can find a 12V timer switch, that would be better.

[friskyfrankie]

If the Rear Window Defroster is on Fuse 6, there are many other things that fuse controls as well so perhaps one of those is the issue as opposed to the rear window defroster? I think it is a 20 amp fuse but working from memory so it needs to be verified.

[Toploader]

If the Rear Window Defroster is on Fuse 6, there are many other things that fuse controls as well so perhaps one of those is the issue as opposed to the rear window defroster? I think it is a 20 amp fuse but working from memory so it needs to be verified.

Frank that makes sense, but I have already replaced two of the defog switches, and in time same thing happens, parasitic drain until the battery goes dead. And, by virtue of dis-connecting the connector from the switch................BINGO!!!!!!!!!!!! No more dead battery. Btw, it has to be a 20 amp because the wire is a number 12 AWG, and if it were 40 amps the wire would have to be like a number 10 AWG

[Toploader]

Oh btw, I intend to wire a relay before the switch to take the load off it.

[jaywish]

Likely you plan to use the run circuit, that sly mentioned, to feed the switch so it depowers the circuit when either the key is turned off or you flip the toggle off. It is going to be a pilot light switch?

[gadget73]

there should be a key-on circuit and a constant hot circuit in there. Wire it correctly with a relay and it will shut itself off with the key. The other thing that stock switch does is provide a timer so it won't just run the defrost constantly. Not sure if there is risk of cooking the traces on the glass or not.

anyway, from the 1986 Lincoln EVTM

white/pink - key on hot
black - ground
yellow - constant hot from fuse link J
brown / light blue - output to defroster

If you want to do this right, using a toggle and a relay

white/pink - to toggle
other side of toggle to pin 85 on the relay
black - to pin 86 of the relay
yellow - 30 on the relay
brown - light blue - 87 on the relay

defrost will shut off with the key and the switch is only carrying however much current the relay needs.

[sly]

Yeah... the 20A is on the toggle side and the 40A is on the switched (constant/load) side. The grid is on the 40A side. The 20A side is just the coil power for the switch/relay.

[Toploader]

there should be a key-on circuit and a constant hot circuit in there. Wire it correctly with a relay and it will shut itself off with the key. The other thing that stock switch does is provide a timer so it won't just run the defrost constantly. Not sure if there is risk of cooking the traces on the glass or not.

anyway, from the 1986 Lincoln EVTM

white/pink - key on hot
black - ground
yellow - constant hot from fuse link J
brown / light blue - output to defroster

If you want to do this right, using a toggle and a relay

white/pink - to toggle
other side of toggle to pin 85 on the relay
black - to pin 86 of the relay
yellow - 30 on the relay
brown - light blue - 87 on the relay

defrost will shut off with the key and the switch is only carrying however much current the relay needs.

Thain I have to sit down and figure out how I will go about effectuating this, one thing is for sure, I would never put another factory switch back in, no matter that it be NOS. Two times putting up with this shit is two times too much:-( And yes, a relay will be part of this exercise.

[Toploader]

Likely you plan to use the run circuit, that sly mentioned, to feed the switch so it depowers the circuit when either the key is turned off or you flip the toggle off. It is going to be a pilot light switch?

Yes pilot light switch.

[friskyfrankie]

Thain I have to sit down and figure out how I will go about effectuating this, one thing is for sure, I would never put another factory switch back in, no matter that it be NOS. Two times putting up with this shit is two times too much:-( And yes, a relay will be part of this exercise.

"Effectuating"? Please refrain from using these "nine dollar college words". While you may be able to converse on these topics with complete erudition, do show some constraint! LOL

[Toploader]

"Effectuating"? Please refrain from using these "nine dollar college words". While you may be able to converse on these topics with complete erudition, do show some constraint! LOL

Yo Duddddddddddddddddddddeeeeeeeeeeeeeeeeeee, my porr parentssssssssss spent a fortune on my edukation

[friskyfrankie]

Isn't that "EDGEAMACATION"?

[jaywish]

Yea Frankie, get off his back. I am pretty sure "Effectuating" is only a $7.50 word.
(Insert the just joshing emoticon of your choice here)

[jaywish]

I think I may have made a circuit once that allowed me to use a momentary contact switch to lock a relay on (using switched power) and another momentary contact to unlock it. That way you could have it turn off permanently when the ignition is switched off and or when you hit the second button to turn it off. Cant remember the logic. Kind of remember using 2 relays.

Is that of interest to you? Control and switching would be low amp side.