I think will be using a 30 amps circuit breaker to feed the hot line which sources all my relays into the cab, attached on back of housing to get the ammeter source. This will emulate the circuit protection existant on headlight switch



Just thinking out loud on my own installation sorry LOL.

This is posible just after get the bulkhead ( and alternator ) upgraded which I have.

i have one on my buddy's wife's 72 duster. i installed it because on his custom harness, an aftermarket headlight switch was used.
VERY good quality product, and TRULY plug-n-play !

Talked to him, gave him dimensions, he's getting me one constructed

Nice Nacho!

Don't worry about the old pics. Those aren't bad at all.

Thanks for the referrals and positive comments regarding my relay harness. I try to build my items with the standard of I'd be proud to use it on my own car.

Rob, your D300 harness is built. Thanks for the purchase.

Sweet thanks, looking forward to getting it installed

please if you still are using the ammeter, don't connect it to the batt, but to the alt stud, to get a correct ammeter reading and don't get stressed the ammeter unnecesarilly with a load wouldn't need to read.

Even if not using the ammeter, it is still often better to connect the relays to the alternator. Way too many people bypass the ammeter thinking all current flows through it (which of course is not correct).
Hooking to the battery on a 'typical' mopar system, with or without the ammeter, doesn't change the fact that the power to the headlight relay will still flow from the alternator through the bulkhead connection, to the mains splice back to another connection on the firewall, through a fusible link to another connection, then finally to the connection to the headlight power relay.
I put 'typical' in quotes because his '76 D300 may have a different arrangement for the power feeds. I don't think so, but I don't know for sure.

Don’t understand why it matters, you want relay power connected to battery.
Alternator supplies the battery.
The trigger for the relay is what flows through the wiring harness, and only requires mA, not amps.
That’s the whole point, remove the large current drain through the factory harness and supply it directly from battery.

Ah ha! That's what a lot of us thought. But in these systems the alternator output does not connect direct to the battery.
The 'typical' wiring arrangement on these cars and trucks was for the alternator to supply the circuit feeds at a welded junction inside the car.
The battery feed joins the alternator feed at this junction.
The battery feed/charge wire is a dead end at the battery.
^This^ arrangement is pretty elegent as it only needs one fusible link, keeps the charge line use to minimum, etc.
It has inherent weakness when equipment needs to be run off the battery, either because its run when the engine is off, or because the amp loads are very high (winch).
It also means there is no noise damping of the current by the battery. That's not a problem with basic electromechanical or even older solid state regulation and ignition but just mentioning it as another reason why its not a design approach used in more recent decades.


Basic power scheme layout illustrated below. Details will vary with year, model, etc.

The alternator powers the car once running, better to pull power at the source. Think about the readings on a voltmeter with the engine off and on. What are the readings and what causes the change.

The factory charge route is not good and it stresses the bulkhead, twice (in and out), when you pull power at the battery. The battery or starter relay are poor choices to pull any accessory power on our old mopars with the factory charge path in place.

Correct, and if you drain the new load from the batt will be constantly stressing the ammeter on charge side ( what really means is this load is sourcing the new accessory ), while being sourced from alt, this issue will be saved... as far alternator is good enough to source it of course.



Correct, the trigger is on original wiring and switches and you are saving them from loads, but the device to be sourced will be still needing the same load to work. The relay will still need to get correctly sourced just like factory did, on a new "path"

I agree with above, I did amp meter bypass and have a wire directly from alternator to battery.
Assumed most people adding relays would have done the same.

X2!

well you can guess I'm not LOL. and my relays are on the alternator line

Same.

Follow the very first diagram shown in this post, best way to reduce loads on the bulkhead connector and factory harness.
Alternator and battery are the same voltage/connection point, once you’ve run the single wire from alternator to battery, makes it easy to tap into harness for headlight relays that run along the fender to headlights.

Thought I would catch this thread up to date, got crackedback's harness installed on my 76 D300 in about an hour, no fuss no muss, lights are "whiter" and brighter and the install was clean as a whistle two (pics are in my thread in the truck forum)

i knew you would like it.
the harness i got for my buddy's duster did the same, but it took me longer to install because now i'm only "half fast" as i was many moons ago.
a great product in my humble opinion !

Rob,

Thanks for trusting me and my product with your hard earned money!

Thanks moparx too.

Happy clients are the best advertisment. I appreciate the patronage.