Alternator wiring, 1st of many electrical questions I'm sure

[lsixt]

See attached photo.

The plug to the alternator is a no brainer. Good thing for me. The other wire that comes out of the harness (missing the connector) appears to want to land right on the terminal indicated in the photo.

What I don't know is are there any other wires that go to the alternator.

My project is nearing the end. It's been long and this board has been a life saver for me. I'm sure that I'll be having many more electrical questions. I have the wire diagram - which helps, but photos appear to be much better.

Example, I have no idea where the positive lead off the battery goes - aside from the starter? Negative goes to ground and that's it?

In any event, I'm taking it one component at a time, so there will be additional questions as I work my way through the whole harness.

Thanks guys,

Len

[jerry]

you are correct. the bottom wire attaches to the nearby post on the alternator. the connection typically has a flimsy rubber boot covering it. they are usually MIA by this time.

the upper connection is a ground between the alternator and the front timing cover of the engine. typically a slightly heavier guage wire, originally brown (designates ground on these cars). get an appropriate length of wire and put eyelets on both ends and attach as necessary.

[lsixt]

Thanks,

See additional image....

This shows the positive battery cable going to the starter (assume it goes on the solenoid). It also shows a positive direct lead to the alternator, and I think the horn relay...???

Another lead off the positive goes to the ignition switch.

The drawing indicates to me hard wires. I get the starter lead - that's fine. But is there a wire that feeds off the positive battery terminal that goes to the alternator, horn relay, and ignition switch too???

My old positive cable looks like it's been modified. The backbone of the cable goes to the solenoid. Then there are two pigtails off the cable,

1 = that's attached to the bolt and is about 11" long with a eye ball connector...

2 = runs out the back of the lead connector that is fairly long, and looks like it has an inline fuse in place - this one terminates with bare wire and it's a bit "burnt" at the end

Then off of the second lead, someone "pigtailed" another red wire that has a 15 amp fuse in line, and terminates with a flat plug connector.

UGH

So does the positive bulky go to starter, the fish eye to the horn relay, the bare end goes where? Then the flat push connector?

Driving me nuts in Tampa,

Len

[tjones02]

Both of the marked positions in your pic can be 4 alt B+... (B+ is the big alt output wire) depending on the favored position for the particular harness.

The Ground should go on one of the three long 5mm diameter bolts that hold the alternator together, the ont near the top with the 8mm nut on it is the one. NOT on one of the two Positive connections you have marked in the pic.

A good pre made alternator ground strap is from BMW, used on the e28 5's and e30's etc... # 12 52 1 285 011.

I like to add another 8 10 or 12 gauge alt B+ wire with good quality heavy duty connectors to my and any customer '02's from the Alt to the Battery or Starter because the original wire gets crystallized and flows less voltage than it should after 30+ years in the car.

Also, when doing charging system work on '02's I check the ground and positive battery cables and recommend replacement when nessisary. And check the integrity of the wires to and from the Alternator and Voltage Regulator for crystallized/corroded wires.

[lsixt]

OK, thanks, I was going to hook it on wrong. I think the first response mis-understood the photo. Ground to the bolt that holds the alternator together, got it. Not to the hex bolt that I pointed to that has a black wire on it, or the other pointed to spot that has a nut half undone. That's where the bare wire with the missing connector can go (either one).

BTW - can you shed any light on the positive cable lead? See my other response ... it's part of this discussion - sort of an add on.

Not having another 02 to copy from, I'm trying to do this by reading and asking for help. I don't claim to be a mechanic or know anything about auto electronics, just a wrench turner - that's me.

Thanks,

Len

[tjones02]

The positive battery should have only one other wire connected to it at the battery, and that's from the cars harness next to the radiator that one goes to the fuse box and the ignition switch among other places that use direct B+ power. Other connections at the Pos + Batt terminal are for aftermarket added on stuff (Remove if not used!). OR an added on B+ from the Alternator (which is good, I do this all the time).

The other end of the positive battery cable (as we know, doh) goes to the 8mm starter lug.

The Ground Neg. - Cable goes to the starter support bracket or baring that, if it's MiA, somewhere near that on the block is fine. The '02 ground cable also has a body ground wire that should go to a clean (no rust and paint) hole near the batt on the body of the car.

the horn relay wires if for the original type horns not add on air horns and such should go to (what year is it anyway?)... on late (74-6) cars have a plug connector for the relay (rather obvious), while the early cars wires should all come neatly from the wrapped harness not directly from the Batt +.

Since the 2002 batt positive cable is NLA I've been using the e21 320i one part# 12 42 1 277 511

The Ground cable is avalible # 61 12 1 350 305