Three Questions on Wiring

[BUDFIVE]

Hey y’all, as the title says, 3 quick questions on wiring. I’m using the Ron Francis chassis wiring harness that comes with the complete kit.

1) In the RF harness and schematics there is 1 wire (light blue) going from the clutch safety switch (CSS) to the solenoid trigger terminal. There is no separate relay shown or implied. In a 2022 forum thread it was mentioned a separate relay is not necessary with most modern starter/solenoid combos. I’m using an SVE hi-torque mini starter from LMR for up to 1995 5.0 Mustangs. There’s no current spec nor did LMR have info on this. I do plan to wire a neutral safety switch(NSS) in parallel with the CSS which shouldn’t change the current flowing through the wire. Anyone have a reason I shouldn’t just connect the Light Blue wire directly to the solenoid?

FYI, I’m looking at moving some of the positive wires from the solenoid terminal to a power distribution bus to clean the wiring up, but that doesn’t change the question-there will be a 2 gauge wire direct from the battery to the large positive solenoid terminal.

2) Same harness and schematics but for headlights: again, no relay shown or implied for the headlights. I’m using a STD Products DS-72 foot switch dimmer instead of a dash mounted toggle for high/low beam selection. There’s no published current max for the switch. My first car (1970 Firebird) had the same floor switch, how cool to go back and it for sure didn’t have low current headlights. On an earlier forum post someone mentioned the FFR headlights are 6.5 A max on high beam. I saw someone had used a floor switch but added a relay. I was planning to just run some copper stranded 12 gauge to and from the switch to/from the dash harness where the 3 dimmer switch wires are. Do I need a relay?

3) I mentioned in my build thread a couple of days ago “ the front harness goes through the DS foot box aluminum slot which I’ve made a small cover for with a through hole. From this through-hole the front harness can go up to the top frame rail or go forward on the middle 3/4 with the front brake line (kind of prefer this). I haven’t decided. Input?”
Any reason it’s a bad idea to run the front harness on the middle 3/4” rail?
198442

[Papa]

I also did a foot-operated headlight dimmer switch on my build. Here is how I wired it:

https://thefactoryfiveforum.com/attachment.php?attachmentid=104221&d=1553358772

[BUDFIVE]

Papa, thanks for the reply. I’m missing something-I don’t see the dimmer switch. The ones I’ve seen, including my DS-72, have 3 terminals: headlight power in, low beam out, and high beam out. The block in the center (five numbered terminals) is a relay? What’s the on/off switch?
Thanks again.

[Papa]

Papa, thanks for the reply. I’m missing something-I don’t see the dimmer switch. The ones I’ve seen, including my DS-72, have 3 terminals: headlight power in, low beam out, and high beam out. The block in the center (five numbered terminals) is a relay? What’s the on/off switch?
Thanks again.

The "switch" is a foot operated switch. I used it to trigger the relay, so only used one side of the switch. The relay switches on the high beams when on and low beams when off.

[BUDFIVE]

OK, Papa, I get it-only requires one relay.

[Dave M]

If you have a standard old school floor mounted dimmer switch you don’t need a relay. The vast majority of them are robust enough to handle pretty much any high beam you can throw at it. The dash witches on the other hand you need to be more careful with some of them want take the juice pulled by some lights.

[edwardb]

I agree the foot mounted dimmer switch should be fine without a relay. I did a quick search and couldn't find any ratings for the one you mention. But judging by the size of the terminals, seems like it's robust. Especially if you choose to change (upgrade...) the kit provided halogens for LED's. Significantly lower current draw with brighter and whiter light. Highly recommended.

The subject of the neutral switch on the TKO has been talked about a lot. I'm guessing the TKX has a similar setup. Some use a relay out of caution. But many don't and seems OK. I know that's no much of an answer. Sorry.

For the wire and brake line routing, most (including me) use the top frame tube. Not the middle one. The middle tube ends up relatively close to the headers. Much closer than the top one. Something to consider.

[BUDFIVE]

Dave M and Edwardb thanks for responding.
On the NSS, I also dug up a 2008 post by Mike Forte on another forum in which he said it’s not a starter safety switch and was intended for computer controlled vehicles, not driving a solenoid. I’ll either not use the NSS or I’ll use a relay. Probably not worth it—more parts to fail, not much more functionality.
On the headlights, seems I’ll be fine with the floor dimmer switch. If anything, people seem to have more trouble with the headlight switch. If I added relays it would be for that. But, LEDs…
On the front harness routing, I didn’t think about the header heat, good point.
Build on!

[runamuk]

Hey yÂ’all, as the title says, 3 quick questions on wiring. IÂ’m using the Ron Francis chassis wiring harness that comes with the complete kit.

1) In the RF harness and schematics there is 1 wire (light blue) going from the clutch safety switch (CSS) to the solenoid trigger terminal. There is no separate relay shown or implied. In a 2022 forum thread it was mentioned a separate relay is not necessary with most modern starter/solenoid combos. IÂ’m using an SVE hi-torque mini starter from LMR for up to 1995 5.0 Mustangs. ThereÂ’s no current spec nor did LMR have info on this. I do plan to wire a neutral safety switch(NSS) in parallel with the CSS which shouldnÂ’t change the current flowing through the wire. Anyone have a reason I shouldnÂ’t just connect the Light Blue wire directly to the solenoid?

FYI, IÂ’m looking at moving some of the positive wires from the solenoid terminal to a power distribution bus to clean the wiring up, but that doesnÂ’t change the question-there will be a 2 gauge wire direct from the battery to the large positive solenoid terminal.

198442

Don't overthink the starter solenoid wire, it doesn't pull very much current since it only operates the solenoid, not the starter. The light blue wire goes from the ignition switch to the clutch safety switch and then from the clutch safety switch to the starter solenoid. There is a mistake in the manual on how to connect the wires to these switches and you need to make sure you connect them to the normally open side, when you depress the clutch pedal the plunger opens and the switch contacts close allowing current to flow to the solenoid.