powermaster alt

91lxntch

Member
Sep 27, 2003
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altoona,p.a
does anyone have a 140 amp alt from powermaster hooked up the 3 wire way...1 wire is not working for me ...could you please tell which wires from the factory harness needs to be cut and spliced with a diode also which wire goes on which terminal on the alt....i know the green w/red stripe gets a diode but does it go on the top or bottom terminal.....but whats the 2nd wire??????????????????
 
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Ive got the one wire and I just have the one big red wire going from the gold post to the positive side of the starter solenoid. It works great. Are you sure its the true one wire alternator. It should have no other ways to hook up. good luck
 
I use the one wire as well with no problems but you can hook it up either way, the powermaster comes with instructions how to wire it stock, im sure you could find it online, they must have an info website or someting.
 
If its hooked up with just the one wire you have to rev the engine up after starting to 'turn itself on', which is called the cut in point. rev the engine to about 2500rpm after starting and it should kick it in.

For the 3 wire hookup you actually only use 2 wires. the main one stays connected. You don't need to use the diode if you have a 91 mustang. simply splice a wire from the #1 terminal on the alternator (the output closest to the battery post) to the green wire w/ red stripe on your stock wiring harness.

The second wire simply turns the alternator on immediatly, which means you don't have to rev up the engine to get it to start working.

If you have underdrive pulleys you should replace the alternator pulley with an 'overdrive' pulley. this will spin the alternaotr faster which really helps at idle or low rpm.

If you still arent' producing over 14volts then you may have a problem with the alterntore itselft (as I did) the good news is you can order a rebuild kit from powermaster for $38.
 
yes mine is a 91 ...ok so which wire do i use SCOTT W .....on my new alt there is offcourse the main heavy power wire running to my battery..then two male terminals .......i understand what your telling me but which exact wire and which terminal....haha thanks
 
Yea Scott is right, you have to blip the throttle to get it to kick in with the single cable, lol, I was hoping that was normal, thanks to Scott for confirming. :nice: According to my install directions the green wire w/red stripe goes to #1 pin on the alternator plus the main batt post.-86-93 fords.
I would experiment and see what works best.
It also says if you use the diode, the banded end must be toward the alternator.
Anyway, hope this helps and good luck.
 
the diode, or rectifier, only needs to be installed on vehicles that have a factory amp gauge an NO indictator light. In this case the banded end of the diode must be toward the alternator. this keeps current from running out the alternator to the coil. if this is not installed the car will continue running.

since 86-93 mustangs have a factory amp gauge AND an indicator light, you will not need the diode. Hold on to it, and if for some reason after installation the car continues to run after the key is turned off you will install the diode on the green wire with red stripe on the stock wiring harness (diode band facing alternator)

Now, on the alternator you have 1 main post (where the main cable connects to the battery). the male pin next to it is called Pin#1, the pin beside it (farthest from the main battery post on alternator) is called Pin#2. You will not be using Pin#2.

You need to run a wire from pin#1 (closest to main battery terminal on alternator) to the green wire with red stripe on your stock wiring harness (the harness that used to plug into the stock alternator.)

thats' it. Like I said, you won't need the diode, and even though its called a '3 wire hookup' your only using 2 wires - believe it or not thats normal in our case.

once again I can't stress the overdirve pulley for the alternator (if your running underdrive pulleys)