MSD alternator connect help

I bought a direct connect MSD 5100 Mustang alternator for my 32 Ford with a 5.0 motor thinking I was going to adapt a stock harness but ended up using a Rebel wiring kit. I have a stock Ford 5.0 connector for the alternator with 3 wires, green/red stripe, yellow/white stripe and white/black stripe which has a small connector on it. My Rebel wiring harness has 2 wires designated for the alternator, " alternator" and "alternator exciter" plus I have a volt gage. No luck with MSD and the Rebel rep tried to help but I must not be getting it. Trying to figure out using a stock wd but these electron paths confuse me. What goes where

 

500 ******** bucks for an Alternator? For that price I'd be on the phone on Tuesday asking MSD for explicit directions on how to hook it up. I'd sure hate to hook it up wrong.

 

I hear you and there suggestion was to replace it with a one wire. I do like the option of being able to reposition the mounting brackets for clearance.

 

Do you have a pic of the alt and maybe the wireing from a manual that may have come with it ? Ron

 

From the instructions -

There are generally three wires
that connect to the alternator;
a battery source, one for an
indicator or warning light, and
a voltage sensing wire.​

So,​

One wire goes to the battery to charge it.

One wire goes where ever you want to sense voltage.

One goes to the idiot light or voltage gauge.

I usually put the sense wire at the junction or bulkhead between the dash and engine compartment. Then check the voltage at the battery, it should be 13.5 to 14.5 volts or there abouts.

http://static.summitracing.com/global/images/instructions/msd-5100_frm28893.pdf

 

Thanks for the info Dane. I have this and a factory wiring diagram but as stated by Mr48chev, do not want to hook it up wrong. I will have another look at the Rebel harness and try and sort it out.

 

The guys at Rebel Wire should be able and willing to tell you which wire does what. We have a couple of them on here and maybe they will chime in.

Asking first beats the hell out of wiring things up wrong and frying something and then asking what you did wrong.

 

Here was the response from MSD;


if you look at this drawing.... Ford 3G schematic

ford msd

white/black s-

ltgreen/red l- charge indicator ( factory charge light)

yellow/white 1/f---field ( turns on and off with the key)

heavy blak/orange battery

p---- not used!

Still not 100% confident that I have the right answer and awaiting the Rebel dudes to chime in.

 

I believe they feel you are using a stock type Ford voltage regulator ? If you are let me know as it is not hard to wire. Ford had 4 terminals on their external reg from the 70's. They labeled them I , A , S , and F. They stood for the I is from the dash alt indicator lite circuit , the A is 12 volts hot at all times , the S is from the stator terminal and the F is the field terminal. I wont waste your time if you are not using the Ford style reg and if not let me know what you are using to regulate it ? Ron

 

It has a built in regulator similar to a 3g alternator.

 

What year did the 5.0 harness connector come from?

 

I have opted not to use the stock connector and will use a universal version instead. The alternator was a replacement for 87-91 Mustang 5.0. I figured out that the red 12 ga alt pwr from fuse box goes to alt batt post. I have a separate 10 ga red wire from alt batt post to start solenoid batt side. Would the white alt exciter wire from the kit be the L/GR wire in the attached drawing? Also can now see that I need to run the wire labeled YW from alt to the alt batt post. This leaves the W/BK wire as I can`t figure out where it connects. I thought that an internal regulator would have the Y/W and W/BK wires internally connected.

 

Looks like the Yellow/White wire also needs to connect over to the Batt terminal on the alternator. The White/Black wire attaches to S terminal on alternator.

The Light Green/Red wire must be connected to the ignition switch and should only have power with the key on. If you want a charging indicator light, connect this light in series like shown in the diagram you supplied. If you do not want a light, wire a 510 ohm resistor in place of the indicator light.

Hope this helps.

 

You can connect the 'alternator exciter' wire from the Rebel kit to the Light Green/Red wire at the alternator connector. Just make sure to wire the resistor in series.

 

The alternator does not have a "S" terminal.

 

I also have a request into the MSD rep thru there online forum, for wire identification on the plug out their alternator. Their schematic shows 4 wires and the alt has 3. Getting closer and appreciate the help.

 

Any more schematics supplied to you by MSD or with the alternator itself?

 

Sorry forgot to add.

Also asked the following;



Also need to confirm the wiring on the plug out of the MSD alternator.
The plug out shows 4 wires but the alternator only has 3, black, grey and red. Am I correct that the black wire is "volt sensing" or "S", the grey wire is "switched 12 volt" or "IF" and the red wire would not be required if we follow the schematic by connecting a indicator lamp or resistor in series with "switched 12 volt/"IF" grey wire?

 

The S voltage sensing wire can be tied into the Batt stud on the alternator. The switched 12 volt I/F wire needs to go back to the ignition switch. The wire at terminal L will need to be connected back to the ignition switch as well with either an indicator lamp or resistor wired in series. You cannot forego connection of any of these wires and have the alternator work.

 

Thanks for all your quick responses and help. I will take another look at it in the morning.
HB32

 

Shoot me a PM and let me know how it turns out.

 

Will do and thanks.

 

so , did you ever finish the install.

 

The battery is in and have connected the alternator the way dt50chev advised. Tying up loose ends and hope to start the car in the next couple of weeks. Still need to install either a 510 ohm resistor or an idiot light in line with the alt wire, the white wire visible in the pic. Heading to Monroe this weekend for parts to finish.

 

So now my problem is that there is a humming noise coming from the alternator with key off. Really regretting buying this expensive paper weight.

 

After countless posts on the MSD forum and direct questions to their tech rep, this is what I get "and if there is a problem with that alt we no longer repair them...but, power master motorsports does"
Well thanks for wasting my time and really helps with my decision on future purchases.

 

This is what I got from Power master on the alt.
"As far as I know the only wiring to the alternator will be the battery charge wire. The original 91 Mustang alternator harness and plugs will not be needed. Does the alternator feel warm to the touch, or have you not left the battery connected long enough to tell? It sounds to me like the internal regulator may be staying excited. This could cause a humming sound, plus a battery drain and if you left the battery connected long enough the alternator will feel warm."
It is pretty bad when MSD has to rely on someone else for support of their own product.

 

Ain't wiring fun ?

 

I enjoy it as it is a challenge and sets the builders apart from the buyers
I read a post several years ago on the HAMB regarding how you can tell a real car guy from a wannabe, ask them what rear end gears they have
Flame away

 

From what I read, MSD quit making those alternators a while ago. I further heard that Powermaster made or supplied the guts for them so that is why MSD sent you there. Can't say this is 100% true, but it would seem to go with what you are being told.