TxFireman1972

iTrader: (8)

In the process of trying to get a bunch of my wiring done on my 89 Mustang Coupe. I already have battery box, cutoff switch and long runs of pos/neg cables done (1/0 welding cable).








I mounted a power lug on the drivers side, behind the fender, when I tucked all of my wires.



On my positive run I ran a short jumper (1/0) from the battery post to the cutoff switch, then ran a long run from the other side of the switch up to the front to hook to the starter (1/0). From there I ran a section from where it hooks to the starter over to the power lug on the drivers side.

I had a brain fart and didn't factor in the alternator. So I have a couple of questions lol.

1) Could I just put the alternator in-line in between the starter and the power lug? In other words, instead of running from battery to starter to the power lug, could I run the 1/0 from the battery to the starter to the alternator to the power lug? That would definitely be the simplest at this point, I just want to make sure thats an acceptable way of doing it. I know the line going to the power lug doesn't need to be 1/0 but I already had it an all the fittings. Is there any drawback to having wire that big?

2) Whats the best way to run the small wire to the starter solenoid? I have the wire on the Mustang that went to the small post on the fender mounted solenoid. Can I just extend that, or do I need some sort of really, or certain size wire?

Thanks in advance!!

i r teh noobz

iTrader: (4)

As long as the alternator output wire is connected to the battery in some capacity, it shouldn't matter where you tap into the positive cable.

The solenoid wire doesn't need to be anything fancy. Just match the gauge if you can. Extending the factory wire should work.

TxFireman1972

iTrader: (8)

What about the field wire for the alternator? I need to be able to switch it with the small post on the cutoff switch.

I've seen this pictured posted literally 100's of times in threads about this topic. My question is, if you kill power to the wire that has the resistor(I know its not a field wire) does the alternator turn off? Because that's what I need it to do.

BP Automotive

iTrader: (3)

That is the excite wire. That diagram is for a 1998 system what was excited by the cluster. If you are running a 99+ pcm and harness the pcm will take care of exciting the alternator.

If you followed the picture the alternator will not be excited when the key is off. (98 & 97 system)

If your on the newer system then the pcm controlls it automatically via the red/green connector cavity 15.


On your t shirt I may have to do black on the lettering and not full color. The company is looking into how it will turn out.

TxFireman1972

iTrader: (8)

Its actually a 2001 5.3 and will be carbed so no pcm. What would be the best way for that?


Black is fine on the shirt

BP Automotive

iTrader: (3)

Just wire like it is in the picture, with the resistor to an ignition source. However, I will point two things that are wrong with the picture.


The connector that goes to the alternator is a metripack 150 connector, not a weatherpack.

Dont use electrical tape, it will get hot and fall off.

If you would like me to build you a pigtail with the connector, delphi heat shrink, the needed resistor, and plenty of wire let me know. Ill make ya a deal on it.

TxFireman1972

iTrader: (8)

Sounds good to me, pm me and let me know how much and where to send it.

TxFireman1972

iTrader: (8)

Can it just go back to the small post on the cutoff switch? Because I need it to be cut off when the switch is turned off.

BP Automotive

iTrader: (3)

It will go to an ignition power source. Once you kill the battery it will kill all the ignition power too.

TxFireman1972

iTrader: (8)

I'll have to look into it and make sure it's NHRA approved to do it that way. Track tech's can be a pain sometimes. lol

MustangLS

iTrader: (5)

I tried running that wire to the small post on my cut off switch and it wouldn't kill the car. The power source for that trigger wire on my car is a switched power.

I've been reading up on this and from what I'm seeing the proper way to wire it so the battery switch works properly is to run the alternator charge wire directly to the battery or the battery side of the cut off switch. That way when the switch is thrown and the alternator some how was still working it's only feeding the battery and everything else loses power.

TxFireman1972

iTrader: (8)

Thats weird. Seems like power is power. Wonder why it didn't stop when you killed the power?

I dont believe that would be NHRA legal would it? Because that still leaves a energized wire running to the front of the car after the switch is thrown. Did you have it wired like this?

MustangLS

iTrader: (5)

The rule doesn't state anything about having an energized wire going up front. The purpose of the switch is to kill the engine and the fuel pump in case of a wreck or fire.

I'll have to get a new rule book but this is from a couple of years ago.

"Any car with a relocated battery must be equipped with a master electrical cutoff, capable of stopping all electrical functions including ignition (must shut the engine off, as well as fuel pumps, etc.). The switch must be located on the rear of the vehicle, with the "off" position clearly marked. If the switch is of a "push / pull" type, then "push" must be the motion that shuts off the switch, and plastic or "keyed" typed switches are prohibited. Also, the battery must be completely sealed from the driver and/or driver compartment. This means a metal bulkhead must separate the trunk from the driver compartment, or the battery must be located in a sealed, metal box constructed of minimum .024 inch steel or .032 inch aluminum, or in an NHRA accepted plastic box. In cars with a conventional trunk, metal can simply be installed behind the rear seat and under the package tray to effectively seal the battery off from the driver. In a hatchback type vehicle the battery box is usually the easiest solution, since the alternative is to fabricate a bulkhead which seals to the hatch when closed. At present, Moroso is the only company which offers an NHRA accepted plastic battery box, part number 74050."

TxFireman1972

iTrader: (8)

Good to know. I guess I just assumed they meant anything energized needed to be cut off.

The part in bold is what made me think it all needed to be shut off. I'll look into it some more. Hopefully you're right! lol

Gray86hatch

iTrader: (83)

I did my alt with the resistor the first time and it didn't work all that great. Had it converted to a true 1 wire and it works great.

The alt need to be connected before the kill switch. It can go right to the switch or battery.

Tim

TxFireman1972

iTrader: (8)

So do you have a long run all the way to the starter and another long run all the way to the alternator? Seems like a lot of extra wire.

Gray86hatch

iTrader: (83)

Yep

Power and ground from the battery to the starter and then power from the alt to the battery. Must do it this way to pass tech.

Tim

TxFireman1972

iTrader: (8)

Isn't that the purpose of the 4-post heavy duty disconnects? The small posts on the switch are for killing the "field" wire on the alternator. That way when the switch is thrown the alternator "turns off". Like the picture I posted above. Not challenging you, just asking.

Gray86hatch

iTrader: (83)

I don't use those switchs just use the two post. I also only use 1 wire alt.

I am not positive that just cutting the field wire will shut the car off when running.

Tim

TxFireman1972

iTrader: (8)

What size wire did you use from Battery to Alternator?