Another Relay Question.....

[theleisure]

Hi Guys,

I'm about to install relays in my Sprite. I'll be using 1 each for high/low beams and one for a reverse spotlight that will we able to be switched on and off from the dash but only when the panel lamps are on and only when reverse is engaged. Could those of you who are good with electrics check my diagram to be sure I've got it right please. One thing I forgot to add to the diagram but that I do have on hand are 30A fuses for between battery and relays.

 

[Sarastro]

Not sure I completely understand your diagram, partly because I don't know what flavor of Spridget you have.

The switch in the bottom right is supposed to be the light switch, right? To do this, you'll have to disconnect the reverse-warning-light function, since there is normally +12V going to the reverse switch and then to the warning lamp, not the power from the light switch.

I can't see any simple way to do this as you've specified. You could go from the reverse switch to the push-pull switch to the relay, but then the backup light would come on whether the panel lights are on or not. In modern cars, the backup light comes on whenever you are in reverse gear, day or night, so it seems OK to me.

 

[theleisure]

sorry, that was a stupid mistake on my part. I have a 66 sprite, no reverse lights as standard. No wires in harness for reverse lights. I have a later model transmission with a reverse switch that I'd like to use. I figured I could send power to the switch from the panel lamp wiring and then send power from that switch to the dash switch so I can decide when I want the reverse spotlight to turn on. The lamp I'm installing is big, 5", and I definitely don't want it on every time I go into reverse.

 

[Ofcalipka]

I don't know why you would need a relay for the reverse lamp unless it has a large power draw. You should be able to add a fuse to the vehicle and run power straight from that fuse directly to your dash switch then to the transmission switch and from there to your lights. From What I see in your diagram there you were going to try and run the reverse lights to the headlamp switch as well which would mean you would have to first turn on your head lights then the switch on the dash then put the car in reverse to turn on the reverse lights. Also why are you running relays to the head lamps? They do not draw enough power to require that unless your trying to fit HID's into a Spridget. Just keep it simple not every project requires a reinvention of the wheel.

 

[JPSmit]

I Think relays are helpful front and back - front because your lights will be brighter and because the switches degrade over time and because there is current loss in the wires. More importantly, it is critical I think for the back if you want to use the panel lights as a power source. Then just adding the relay switch part to that circuit should keep the smoke in the wires where it belongs. Don't forget you can use the taillights for power also as the panel lights only come on when the head/ taillights are on.

Here is what I think for the rear

 

[JPSmit]

BTW, here is a great headlight diagram - worked for me

https://www.advanceautowire.com/

look under headlight relay kit

 

[Ofcalipka]

I still don't see a need for the relay other than to have one extra thing that could knock your lights out. As far as switches degrading over time sure like 20 years from now when you should be redoing your car anyways. What little bit of extra light you could get from that extra .020 volts really won't matter. I would just run a wire from the fuse to the toggle switch to the transmission then straight to the reverse lights.

My recomended schematic:
<<--[Battery]+--[Fuse]--[Dash switch]----[trans switch]----[reverse light]-->>

Remember when you modify things to your own liking there are no manuals or wiring schematics to help you later if it breaks unless you make one that you can understand even after you no longer remember doing the repair. Also you need to be able to find these manuals or schematics say in 5-10 years time when you need them.

 

[jvandyke]

The dipswitch in my '63 was destroyed, by what exactly I don't know. I added relays for high and low beam during the rewire and my headlights are much brighter. The point of keeping it simple is well made though. I lost my low beams yesterday and I'm sure it's because the ground (added by me for relays) I thought I had fixed up well came loose again.

 

[theleisure]

Thanks JP,

I'll go panel lamps- dash switch- reverse switch- relay per your diagram. Makes more sense. Thanks for the link to the adv autowire diagram.

my dipswitch is dead too, came that way from a previous owner. I've read that that can happen when upgrading front lamps without adding relays. I'm sure the same would happen to the reverse switch if I would link it directly to a 5" halogen spotlight.

 

[jvandyke]

my dipswitch is dead too, came that way from a previous owner. I've read that that can happen when upgrading front lamps without adding relays. I'm sure the same would happen to the reverse switch if I would link it directly to a 5" halogen spotlight.

That could be what happened to mine too. Car has halogens, no relays until I put them in. I replaced the dipswitch with one out of a Comet.
thread

 

[Bayless]

I think I see an error in your diagram too. It looks like you have the battery connected to pin 85 with pin 86 grounded. In that case the relays will both be energized all the time, even when the ignition and lights are off. This will be a small but real battery drain while the car sets in the garage. Also, with the switched wire connected to pin 30, the full current draw is sitll through the switch, thereby defeating the purpose of the relays anyway. Instead the battery should go to pin 30 and the light switch wire to 85. I think that is the function you wanted.

 

[theleisure]

battery to 30 and switch to 85, thank you.

 

[Hairyone]

Hi , just seen your post as I'm about to re-wire my BE.
You actually only need one relay to do both high & low beam.
On the foot switch take common terminal to ground, one of the others (either one) to operate a change over relay, so that when the relay is not energised the lights are on low beam, kick the foot sw & provide power to the relay, this'll switch the headlights to high beam.
Having said that, I'm actually going to use two relays but in the above configuration, each fused separately. one for each left & right. I'm going to use 100/80W bulbs.
That way I've two separate circuits, so if one fails I've still got one light.
20A relays 16AWG wire.

Reverse light. I've a torch in the door pocket.