What all oughtta be on relays?

[maytag]

[RRoller123]

But brighter headlights is certainly a big advantage!

[baltobernie]

But really, putting relays everywhere adds lots of complexity and adds lots more stuff to go wrong. And a relay is a switching device, just like a switch, so you are not eliminating a switching device, just adding a different one.

Agreed ... and then some. Scratch the word "different". He still needs a headlight or wiper switch, plus he's adding a "remote switch" (relay) to the circuit. So yeah, twice as much stuff. And a short or open on the (old Fiat) control/trigger circuit will have the same consequences to the headlights or wipers as without the added relay and new wire.

I'll continue to bow down to those who created from dust what we know as FIAT.
Keith

Here I'll disagree. Because of some unique exterior lighting regulations, European cars evolved differently from US ones. Nowadays, of course, the differences are minor, and are probably accomplished with software. But when our Spiders were new, they had a different nervous system than Chevys. I'm all in favor of removing the brake lights, headlights, etc. from the ignition switch. And that hazard circuit The best way to accomplish this is to rewire the car with a USA-style wiring diagram.

RRoller, if you have a slow-running water pipe, you fix the pipe, right? You don't add new pipe along side the old, and use the old pipe to turn a valve on the new.

[spider2081]

All the comments are good food for thought regarding the relays and need to be considered.

I agree the original Fiat wiring is good quality and unless it has been really damaged or or messed up by previous owners I would not replace it. The terminal ends used on the wires do deteriorate over time. This is particularly true of the push connectors on the ground pods. As previously mentioned these terminals can be replaced with good quality crimp terminals and shrink tubing.

Regarding relays.
The current to activate a Bosch 30-40 amp contact rated is about 0.025 amps. and the relay activates at less that 7 volts.
If an old ignition switch has 1/4 ohm resistance across the worn contacts that is too small to be measured with many digital ohm meters. A head light draws about 7 amps at 13.75 volts. The 0.25 ohm resistance of the worn ignition switch drops the voltage at the headlight to 10.3 volts. This greatly reduces the headlights brilliance. The same old ignition switch connected to a Bosch relay reduces the voltage activation the relay to about 13.6 volts so the relay doesn't even know the ignition switch has a bad contact. If the relay contacts are fed directly from the alternators output wire then the full 13.75 volts gets to the headlight. New ignition switches cost about $100 and posts here state they are not the quality of the original switch. A Bosch style relay costs between 3-8 dollars plus wire and terminals. So total cost is less that $20. Plus the extra time to install.

No question more connections, more points for possible failure, and more difficulty for circuit to be trouble shot in the future especially for someone who didn't install the relay.

I think relay circuits can be a viable option for some of the Fiat circuits.

[surfingfreeman]

Nice explanation of how a worn ignition switch adversely impacts power distribution to various systems, I'm in favor of relays just have to sit down at the drawing board.

[RRoller123]

So I must admit some confusion on the posts here. Do some of you think that the loss in reliability by using a relay is not worth the increase in lumens for the headlights and foglights, or the increase in windshield wiper speed? I can't agree with that tradeoff.

[majicwrench]

If you have dim headlights, know that the cause is something like, say, the ignitions switch, and wish to use a relay to improve the situation, go for it, sounds like a good solution. But to just put relay in every circuit is silly.
Personally, my 72 has nice bright headlights. I should measure the voltage and see how much it drops thru everything without the relay.
Also personally, as a professional mechanic, almost everytime I see a vehicle with some sort of wring meltdown, it is due to consumers attempting to add stuff to their vehicles. Want a nice dependable rig?? Leave the wiring the way the factory intended as much as possible.
Keith

[maytag]

[majicwrench]

The resulting loss of reliabily by adding a relay is because now you have two switches that could potentially fail, plus a large increase in wiring and connections.

Was just outside sitting in the sun eating some chips (been a long winter) and thinking if my headlights get dim, due to the ignition switch, I would probably just wire the headlights direct to the B+, and just shut them off like I do my Chevy pu. Not that I couldn't do a relay, I have all the parts, the relay, the connector for the relay, wiring, connectors etc in stock here in the shop. I would just keep it simple. To each their own.