Alternator Wiring Mod(s)?

[markinms]

87 BII 4X4, 5.0L & AOD.

I installed 1998 Explorer FEAD. I read the alternator is a 130 amp G4. The wiring is simply a 2-wire plug and a "bat" wire that may or may not go to the Bat (+) or starter relay on my installation.

My BII alternator wiring runs to a three pin plug on the driver's side, then into the firewall. I'm assuming the large wire goes to the fuse panel, not sure though as wiring diagrams I have don't really show for sure.

Most diagrams I've seen here on TRS and on the internet show the large wire running to the starter relay or bat (+). This is how the bat is charged. Alternator upgrade articles in the tech session even show this and the need to upgrade the wiring to handle a 130 amp alternator.

Now with all that said, has anyone else installed the Explorer FEAD and used the 4G 130 amp alternator? How did you modify the stock BII/Ranger wiring? Did you run the large wire like the original or connect it to the bat (+) or starter relay?

Any and all help is appreciated.

Thanks!

Mark

 

[holyford86]

I've never installed a 4g "pancake" alternator in a first gen but I've installed the very similar wiring wise 3g unit several times. I've always hooked the large power wires to the stud on the alternator AND added a second wire directly to the battery or hot side of the starter relay. The factory setup is at most 65 amps and you're likely to have an electrical fire if you don't add the secondary wire as the factory system was never meant to handle that kind of current.

 

[RonD]

The B+ stud handles the output AMPs so need to be FUSED and connected to Starter Relay Battery post, which is a direct connection to Battery "+"
Starter relay post is the power distribution post for 1987 vehicle, it will have several Fusible links attached for other systems.

For 130amp you need to double up the current wire and fusible link on B+ as holyford86 said.

The separate two or three wire connector is for the internal Voltage Regulator, three wire connector has a short jumper wire, usually white, to connect voltage regulator to Stator in alternator, 4G did that internally.

On the two wire connector will be the Voltage Monitor wire for Voltage regulator, yellow wire maybe.
It can be connected to B+ with a fusible link, or use current wire, that should be connected to starter relay battery post with a fusible link, in later years it was connected to 10 or 15amp fuse in engine fuse box, but same difference, it monitors alternator output(system voltage) for the voltage regulator.

Green wire on the two wire connector is ON/OFF switch for the alternator, it should only have 12volts when key is ON, no volts key OFF.
This is usually the Battery Light circuit, so if you have a battery light on the dash the green wire runs to that bulb.
When you turn on the key the bulb gets 12volts which goes thru the bulb to the green wire and to the Voltage regulator.
If alternator is not spinning(working) then it is a GROUND, so Battery Light bulb has 12v(key on) and a Ground, so it turns on, glows.
And this 12v from battery light circuit, now at the voltage regulator, gives alternator "startup voltage", an alternator doesn't produce voltage just by spinning it.
It increases INPUT Voltage by spinning it
So it needs a "startup voltage" to work, the green wire.

 

[markinms]

Thanks guys for the feedback. Good info to work with.

I appreciate the help!

Mark