Pretty stupid alternator question

[Vovchandr]

Since Ive been through some alternators already I want to make sure I do this right. 

 

I know typically alternator just needs the pigtail plug and a single wire

 

I appear to have two wires that used to be wired up to it. I don't believe I have any before pictures but I do believe they were there together.  Second wire hides in the harness. 

 

Anybody know what it could be?

 

2001 Zetec 

[Pokey]

My guess to the starter, on its way to the battery.

Edited May 24 by Pokey

[Vovchandr]

11 minutes ago, Pokey said:

My guess to the starter, on its way to the battery.

 

Right the one big red one goes directly to starter which looks to go to battery. 

 

It's the second wire I'm questioning 

 

It hides into the pigtail harness to the alternator. 

 

My pigtail only has two of 3

 

What does middle pigtail wire do?

 

 

Edited May 24 by Vovchandr

[Pokey]

Sorry, misunderstood.

 

Are you asking about the black wire with the ring terminal?  That looks like a chassis ground.  The loom has one up front for the light circuit.

 

Or are you asking about the “missing” wire in the pigtail?  I don’t claim to know but would guess it is for the indicator light we don’t have.

[Vovchandr]

31 minutes ago, Pokey said:

Sorry, misunderstood.

 

Are you asking about the black wire with the ring terminal?  That looks like a chassis ground.  The loom has one up front for the light circuit.

 

Or are you asking about the “missing” wire in the pigtail?  I don’t claim to know but would guess it is for the indicator light we don’t have.

 

Yes loop circuit. 

 

Makes sense on both accounts. If it's ground that would make sense why my alternator didn't work last time as I connected both those terminals together on the alternator. 

 

Does the alternator need a ground? I believe there is a terminal for it. 

 

I don't think I'm combining those two again. 

 

I also don't think it's long enough to reach chassis as its ziptied together from before. Im fairly certain it goes on alternator somewhere, just not the same area as main power 

[Pokey]

The alternator itself is grounded through its mount.  

[CarlB]

Most Fords have a light on the dash to warn you if the alternator isn't working. It also is used to excite the alternator and some people say it makes the voltage more stable. The wires on the plug generally are power from the battery. Power to the ignition switch and the return after the light. The light is wired with power in on both wires and goes out when power is fed in both directions. A one wire alternator connects the light connection to the power connection internally or at the plug and the ignition switch power comes from someplace else. You need to verify how your car is wired and make sure you wire the alternator appropriately. Sorry I couldn't make this easier, but start with a Focus wiring diagram and see what is different on the Caterham.