Farmall 706 led headlight configuration

[706man]

Hey all,
I am switching out my headlights to LED on farmall 706 gas(1963). I have four in fenders, two at front top of cab and one reverse. Currently the power for the lights was attached to the power in for the push button starter button. And I have purchased a fuse box, a four pin relay and in-line fuses.
Question is if I should still use the current power that the old lights used or wire directly to battery? I am thinking using the current power configuration since I would be incorporating the in-line fuse(s) and the relay. Couple of different ways to do this but hoping all would be safer than the current way they were since I had 7 lights on old tractor wiring circuit. Just interested in thoughts on best location to wire the power in so it gets power when key is on. Or wire direct to battery and remember to turn lights off. Thanks

Mike

 

[Rodney51Cub]

I would wire it through the ignition switch. You did not say how many lights you would want on at a time. It depends on that as to using the original light switch or adding another switch to control how many lights are on.

 

[used red MN]

Currently the power for the lights was attached to the power in for the push button starter button.

Someone funky fingered that wiring. Originally the lights were wired so that they had power even with the ignition off. The original engineers knew that running the amps required by the lights was not a good thing for the ignition switch. If it was me I would wire them up as original again powered through your relay taking power off of the battery post on the starter solenoid.

 

[706man]

7 lights. Two forward at top of cab, 4 in fenders, one backwards. Probably don't need that many but hate to leave the headight fender holes empty.

 

[Jim.ME]

What is the total amp load of the 7 lights? If you want the lights disabled when the key is off, use the key switch to power a relay which can send power to the light switch. That removes the light circuit current from having to pass through the key switch while retaining the no lights status when the key is off. The key switch will only see the relay's coil draw that way.

 

[706man]

Total amp load between and 15 and 16. I will be using 14ga wire. Just undecided on light type and if I really want 7. If I buy 2 for front and 1 for back and they are really bright then might call it good.

 

[706man]

If you want the lights disabled when the key is off, use the key switch to power a relay which can send power to the light switch. That removes the light circuit current from having to pass through the key switch while retaining the no lights status when the key is off. The key switch will only see the relay's coil draw that way.

So just so I am understanding. Power would come off key switch, then an in-line fuse, THEN to relay and then to the rocker switch, out to lights? Only reason asking is I am kinda trial and error with tractor electrical. Everything is hooked up on my work bench with car battery, fuse box, relay, in-line fuse and rocker switch and one headlight(not necessarily in that order). Blew three fuses until I got it right.
So order of components of whatever setup I do is crucial

 

[Jim.ME]

Do you want all the lights on at the same time? Or do you want to have a multiple position switch (or multiple switches) so you can select different groups of lights?

I would go from the key switch to the relay's pull in coil. I would take power for the relay's load circuit from the battery post on the starter to a circuit breaker (or fuse) rated at 20 or 30 amps depending on the rating of the relay you have. The out going side of the relay's load circuit runs to the light switch, or switches, then to the lights.

Does your relay have a diagram of its internal wiring on it so you can ID the terminals on it?

 

[706man]

Here is diagram of relay. Probably all switches on at once.

 

[Jim.ME]

Here is diagram of relay. Probably all switches on at once.

In your case, 86 would be the wire from the key switch. 85 would be ground as shown. 30 would be power from the circuit breaker or fuse. 87 would go to your light switch or switches.

 

[BarnyardEngineering]

So just so I am understanding. Power would come off key switch, then an in-line fuse, THEN to relay and then to the rocker switch, out to lights? Only reason asking is I am kinda trial and error with tractor electrical. Everything is hooked up on my work bench with car battery, fuse box, relay, in-line fuse and rocker switch and one headlight(not necessarily in that order). Blew three fuses until I got it right.
So order of components of whatever setup I do is crucial

No. At least, I don't think so based on my understanding of what you described.

You only want the electricity that activates the relay to come from the key switch. The power that actually makes the lights, light, should come from a fused connection, direct from the battery. Breaking it down into three separate connections makes for less to remember:

Key switch - rocker switch (or factory light switch high beam terminal) - relay 86

Battery - fuse - relay 30

Relay 87 - each light - ground

I wouldn't use any smaller than 12ga. That's just me, though. It's not entirely necessary. 14 is probably fine for LEDs.

 

[Jim Becker]

In case it isn't obvious, the ways to wire it as described by Jim.ME and BarnyardEngineering are not the same. Don't get confused by mixing their descriptions together. But either way will work. Jim put the light switch between the relay and the lights. BE put it between the key switch and the relay.

Advantage Jim: You can put your lights on multiple circuits with individual switches and still have them all shut off by the single key switch. Disadvantage: Relay is energized any time the key switch is on. Light switch has to carry full current used by the lights.

Advantage BE: Relay is only energized with the lights on. Light switch only carries enough current to run the relay. Disadvantage: All lights must be controlled by a single switch.

Your choice.

 

[706man]

In case it isn't obvious, the ways to wire it as described by Jim.ME and BarnyardEngineering are not the same. Don't get confused by mixing their descriptions together. But either way will work. Jim put the light switch between the relay and the lights. BE put it between the key switch and the relay.

Advantage Jim: You can put your lights on multiple circuits with individual switches and still have them all shut off by the single key switch. Disadvantage: Relay is energized any time the key switch is on. Light switch has to carry full current used by the lights.

Advantage BE: Relay is only energized with the lights on. Light switch only carries enough current to run the relay. Disadvantage: All lights must be controlled by a single switch.

Your choice.

Jim, thank you for that! That will be a huge help. Ordering the lights right now. Thanks to everyone else too. Great information!

 

[BarnyardEngineering]

The way I described it is how relays are typically utilized. You use a relatively light-duty switch to control the heavy-duty relay. The relay carries the electrical load from the lights instead of the switch.

No offense to Jim.ME, but I'm hoping he was just mixed up in his description, because it defeats the purpose of the relay.

You do not want to run the entire light load through the key switch, or off the starter button. It is acceptable to power the relays off a source like that.

If you want to be able to switch lights on and off in multiple groups, you would use multiple relays, controlled by multiple switches.

You could also creatively use the factory light switch on your tractor. First, you'd cut the little spring (low-beam resistor) off the back.

"INST" would connect to a relay that controls your instrument cluster lights and, let's say, your outer fender lights.
"TL" would connect to a relay that powers your flashers and/or red tail lights.
"HL" would connect to a relay that powers all the rest of your forward lights.
"RL" would connect to a relay that powers your rear lights.
DISCLAIMER: I may have TL (tail light) and RL (rear light) reversed.

Then things would work like factory. First position would activate the outer fender lights and your flashers. Second position would activate the rest of your forward lights and leave your flashers blinking. Final position would shut off your flashers and turn on your rear flood lights.

This way is a little more complex, but you can add as many lights as you want and not overload the factory switch. That factory switch is barely adequate to power the six factory lights on a 706 with flat top fenders.

 

[Jim.ME]

The way I described it is how relays are typically utilized. You use a relatively light-duty switch to control the heavy-duty relay. The relay carries the electrical load from the lights instead of the switch.

No offense to Jim.ME, but I'm hoping he was just mixed up in his description, because it defeats the purpose of the relay.

You do not want to run the entire light load through the key switch, or off the starter button. It is acceptable to power the relays off a source like that.

If you want to be able to switch lights on and off in multiple groups, you would use multiple relays, controlled by multiple switches.

You could also creatively use the factory light switch on your tractor. First, you'd cut the little spring (low-beam resistor) off the back.

"INST" would connect to a relay that controls your instrument cluster lights and, let's say, your outer fender lights.
"TL" would connect to a relay that powers your flashers and/or red tail lights.
"HL" would connect to a relay that powers all the rest of your forward lights.
"RL" would connect to a relay that powers your rear lights.
DISCLAIMER: I may have TL (tail light) and RL (rear light) reversed.

Then things would work like factory. First position would activate the outer fender lights and your flashers. Second position would activate the rest of your forward lights and leave your flashers blinking. Final position would shut off your flashers and turn on your rear flood lights.

This way is a little more complex, but you can add as many lights as you want and not overload the factory switch. That factory switch is barely adequate to power the six factory lights on a 706 with flat top fenders.

View attachment 132276

No offense taken and I hope you are not offended by my thoughts.

Depending on the loads I will agree a relay after each switch may be needed, instead of the single relay as I described. In my opinion (we all have one of those) with the load of 7 LED lights being used to replace seal beams in kind, as it sounds like he is doing from what he posted, one relay with switches after it will handle the load without issue if he doesn't want to buy and wire multiple relays. The equivalent LEDs will likely draw only about 1/2 the amperage of the original incandescent or Halogen seal beams. I have been using fused 30-amp relays that have multiple circuits coming from them, with switches after the relay, with no issues. I have several tractors with the power to the multi position light switch powered by one 30-amp relay which is controlled by the key switch or an oil pressure switch with no issues.

Are you suggesting he use the original light switch with a separate relay after the switch for each switch position? That would be 4 relays for the light circuits shown. How is my method of using a relay ahead of the switch any less correct than the one fuse or circuit breaker generally found ahead of the original switch? How many original tractors of the vintage here had an individual fuse in each branch to a given light group off the original switch?

The key to any of this is knowing the draw of the lamps, and the ratings of the circuit protection, switch(es) and relay(s). Either of our methods can work just fine. Two roads to the same end.

 

[706man]

I have one question after both your last comments. If you were both here wiring my lights together, who would be the first one to crack open a cold one? I am kinda bummed. Just took all the old lights off the tractor. All 7 still work. I better focus on how much safer and brighter the new 7 will be.

 

[Jim.ME]

I have one question after both your last comments. If you were both here wiring my lights together, who would be the first one to crack open a cold one? I am kinda bummed. Just took all the old lights off the tractor. All 7 still work. I better focus on how much safer and brighter the new 7 will be.

Nothing against anyone having a cold one but it wouldn't be me.

 

[BarnyardEngineering]

Are you suggesting he use the original light switch with a separate relay after the switch for each switch position? That would be 4 relays for the light circuits shown. How is my method of using a relay ahead of the switch any less correct than the one fuse or circuit breaker generally found ahead of the original switch? How many original tractors of the vintage here had an individual fuse in each branch to a given light group off the original switch?

Yes, that is exactly what I am suggesting.

The original switch was BARELY adequate for the five factory lights on bright, and farmers often installed higher-wattage halogen lights and more of them, all off that switch. That often led to switch failures, burned wiring, perhaps even an occasional fire, and general frustration.

The goal here is to spread the load out across adequate wiring and switching capacity. It also makes the system expandable. You could put 14 lights on the tractor, add light bars, etc... turn the thing into a the bloody sun if you want.

Honestly with LEDs it's probably not even necessary if you're going to stick with the factory configuration, maybe a couple extra... You can just wire it up factory and not bother with relays or anything because the requirements for LEDs are so much lower than incandescent bulbs. 6-12W vs 35-50W per bulb. I would still recommend eliminating the resistor wire because the LEDs may not react well to it.

 

[Jim.ME]

Yes, that is exactly what I am suggesting.

The original switch was BARELY adequate for the five factory lights on bright, and farmers often installed higher-wattage halogen lights and more of them, all off that switch. That often led to switch failures, burned wiring, perhaps even an occasional fire, and general frustration.

The goal here is to spread the load out across adequate wiring and switching capacity. It also makes the system expandable. You could put 14 lights on the tractor, add light bars, etc... turn the thing into a the bloody sun if you want.

Honestly with LEDs it's probably not even necessary if you're going to stick with the factory configuration, maybe a couple extra... You can just wire it up factory and not bother with relays or anything because the requirements for LEDs are so much lower than incandescent bulbs. 6-12W vs 35-50W per bulb. I would still recommend eliminating the resistor wire because the LEDs may not react well to it.

In his first post he said he was swapping the current lights to LEDs, in the same locations, so overload of the switch should not be an issue (but it is a used switch). We have given him options. He can choose his path forward from here.

I understand your points and if he adds stadium lighting, I would very much say that should be on its own, separate from the OEM lighting layout. One of my points was that by operating the relay via the ignition or oil pressure switch, the lights could not get turned on, or left on, when the key is off.