Relays

[Marc]

Starting with the `71 model year the ignition switch got an extra set of contacts, labelled "X", to control accessory loads like the freshair fan - they also feed the headlamp portion of the lighting switch (the park/tail and dash lamp portion of the switch is still fed from Term 30, which is "hot" all of the time).

The lighting switch must "match" the ignition switch (i.e. pre`71 or `71-up), if it doesn't extra jumperwires are needed and the feature of having the headlamps turn off with the key is lost.

[CBDZ]

Gotcha. Just to clarify, this is for my fiberglass buggy, and I am starting from scratch. I am trying to minimize the amount of wiring from the dash to the fuse block to the relays.

[Marc]

Do you intend to use a stock lighting switch? What about the steering column/ignition switch? Will it be pre`71 or `71-up?
The simplified diagrams you furnished do not recognize the need for a Hi/Lo beam switch or relay. How would you prefer to accomplish that function (floor button, t'signal lever trigger, or what)?

[CBDZ]

Maybe I should have been more clear in the intent of my question. I'm not specifically asking for the use in head lights, but in a general use of a relay, and if there is a right or wrong way to install the switch which activates it. Is is bad practice to have a hot lead to it at all times? Could I eliminate unnecessary components by wiring things one way or another?

[Marc]

...in a general use of a relay, and if there is a right or wrong way to install the switch which activates it...?

No. The relay has no brains - the notable exception is for the case of certain modern relays which have an internal diode on the control circuit - that type requires special consideration, but the pragmatic solution for ancient cars like ours is to simply avoid that type of relay
A simple (non-diode-equipped) relay will never care which "side" the interruption of its control circuit happens to be on...only ancillary considerations determine what the "best" arrangement might be for a particular circuit. For example, if it's desired to have a pilot lamp that indicates when there's power to a load you could choose to power it from either the switch which operates its relay or from the relay output...either way works, and it doesn't make a heckuva lot of difference which way you choose (so long as you remember how you did it when the need arises to troubleshoot a problem)...but if you wire the control switch to the ground side of the relay you only have one option (relay output) rather than the two choices open should you wire the control switch on the "power" side of the relay.
Because you're working with a 'glass-bodied car, there's no ready source of ground handy at each component so a ground wire must be provided should you choose to place the control switch on the ground leg...overall, IMO the wiring (and your life) will be simpler if you keep your control switches on the "hot" side - as per the LH diagram you provided.

[Ol'fogasaurus]

CBDZ I’m running a glass buggy with minimal wiring. I run driving lights, no windshield which means no wipers, stop lights and tail lights, a (fused) CB and not much else.



I run a circuit breaker box that has switched side and a hot side (I don’t think this particular box is now made but I am sure you can find one somewhere).

I run a 55 AMP master CB from the rear forward to protect the long run. I have an aftermarket ignition switch with a key start which I am going to replace with a starter button on the dash and one in the rear to bump the engine when adjusting valves. I also have another CB to protect something but I forget what right now .



This was taken during rough wiring but this is a bussed ground terminal. It also shows the relay for the driving lights.

There is an oil pressure light and while I don’t have one now (I use a diode) but it will have an alt idiot light soon.

This is a minimal wiring job and it works for off-road use only in a glass buggy. Each of the circuits is separate in case of problems.

Lee

[Dale M.]

Lots of wiring solutions here.... Use search feature....

http://www.mydune-buggy.com/gallery/index.php?cat=10001

Dale