Silkworm

What years, if any did FCs come with NON single wire alternators (i.e. just the wire off of the + terminal on the alternator, down to the battery)

Did any years come with wiring for voltage regulators?

I've gotta pull my alternator tonight, not getting any charging to it, and it's brand new. I know the wire is getting 12V with the engine off (put the pos voltmeter to it, and grounded, 12V) and connected to the battery ok.

The battery takes charge (using my battery charger, no problems)

So I'm left with a dead alternator (hard to believe from a rebuilt unit from the store, 0 miles), or maybe it's froma year of FC that had an external voltage regulator (reaching here)

PaulC

j9fd3s

iTrader: (3)

i think 79-80 is the last year for external regulators.
the stock fc alternator (actually 84-up) has 3 wires.
the b+ (goes from the +battery to the post on the alt)
and then there are 2 in the back, im not 100% sure what they do off the top of my head, i think 1 does the voltmeter.
http://brfoundation.com/RX-7/alternator.htm

mike

Silkworm

Oh... Interesting.

Seeing as my harness has nothing for those two wires at all, that I can see.

Time to bust out my FSM again.. Thanks!

PauLC

Aaron Cake

iTrader: (1)

Many times the two wires at the back of the alternator come disconnected...I have not looked up at what they do, but it does not seem to effect operation...Not that you shouldn't connect them or anything, this is just what I have seen.

Silkworm

K.. I'm just wondering why I don't have any connectors for it.. (or maybe I do and I'm just stupid )

PaulC

Aaron Cake

iTrader: (1)

Perhaps someone replaced the alternator in the past and cut them off?

j9fd3s

iTrader: (3)

they are on the same harness as the cas,and the b+ alt wire. one of the wire does do something for the charging. also remember the case of the alt has to be grounded, so if you painted everything....

mike
20b fc

HAILERS

I can't believe nobody has identified what has been done to this car! Its the famous ALTENATOR MOD. Good for eight and a half hp, minimum , on a cloudy day.

If for some reason you want to undo this mod, then look at the jpg that is attached. The deadended wires are there somewhere near the back of the altenator. The electrical plug is highlited in the jpg. Don't be surprised if your car does not run as strong when you put it back to stock.

Silkworm

Beautiful.. Gotta love those 8+ HP.. However, not being an EE, so correct me if I'm wrong, but those two wires appear to only be for the alt not charging indicator relay, and should have 0 impact on my alternator not charging..

Thanks for the pic Hailers

NZConvertible

Bingo!

HAILERS

Sorry to let NZCONVERTIBLE get in between posts. I just realized that my idiot lights havn't been coming on today, and sure enough the darn things are not on. I had to resolder the CPU about three months ago to get that relay to pull in. So much for my soldering skills.


Those wires are for turning the idiot light cluster lights on when the engine is not turning the altenator. I was sooooo happy the day I did that solder job and could get up in the morning and see the whole shebang lit up. Cars starting to bug me. Seen a good Boxster lately? Sorry about the smart *** post. I'd insist they sell you the right alternator next time. Should have that two socket plug(jack) on the back.

EDIT: Darn belt is frayed too. Well some good came of reading the Forum today. Also suspect I'm running with my 82's altenator on the 87 and vice versa. The days gone in the toilet since I got home.

[bnd]

Here's my personal experience with the mystery plug. Just to clarify, I know there's something screwed with the electrical system in my car. The voltmetre tends to jump when the car is running. This is especially the case when you step on the brakes.

Anyway, the plug on the back of my alternator came undone on me. I happened to be driving at the time and my car died in the left turn lane of a busy intersection. The battery was completely dead... There wasn't even enough juice for my hazard lights to work. As fate would have it, the battery in my cell phone was dead as well. Not fun and not recommended. Unless you want to meet a cutie who'll lend you her cell phone

So I had it towed home and tried to jump it. No go. It would run, but the minute the jumper cables were disconnected it would die again. So I checked the usual, battery terminals, cables, etc... Finally tracing the wire to my alternator I noticed that the plug had come out. So I plugged it back in and jumped it again. Well, what do you know? the battery started to charge again.

HAILERS

The following from How Stuff Works:

For excitation of the field to occur, the voltage induced in the stator rises to a point that it overcomes the forward voltage drop of at least two of the rectifier diodes. Before the diode trio can supply field current, the anode side of the diode must be at least 0.6 volt more positive than the cathode side. When the ignition switch is turned on, the warning lamp current acts as a small magnetizing current through the field. This current preexcites the field, reducing the speed required to start its own supply of field current.

My alternator works just fine without the plug connected, with the exception of the idiot cluster lights not working. I just thought the above words are of some interest. Not a lot, but some.















--------------------------------------------------------------------------------

hugues

Hmm,
if that plug in the back of alt is not connected then the voltage regulator has no knowledge of voltage at the battery and cannot adjust how much current needs to go through the alt rotors to charge the battery.
It also provides field current before the diode trio kicks in (and "self-powers" the alt), this makes the alt easier to turn when you start the car.

So, I don't think it is a good idea to have it unplugged,
but it is just my 2 cents.

Hugues -

HAILERS

Hugues.....I'll keep it plugged up. Just took it off to see if anything was effected. Thankyou. I still think Silkworms wires are there somewhere. Someone probably knocked the plug off and stowed them under some wrapping, electrical tape etc.

Silkworm

Ok, you guys will enjoy this one.

No, the BW and WB wires do *not* exist in my Engine harness. The connector has blanks in both locations where the engine harness meets the front harness.

Furthermore, the front harness has the BW wire in the wrong place, and both locations where the original BW WB wires should be, I have brown wires.

Anyone wanna guess??










Automatic harnesses...

****! I pulled this out of a car, but based on feedback I got here, there was nothign different between man and auto with regard to the front harness. That is incorrect.

So.. on the auto, the alternator wiring is on the EMISSIONS harness, not the engine harness. They take up the connector pin locations for a ground (I think), and for boost meter on turbos..

See, the Emissions harness is a manual harness.

ARGH..

So.. gotta find those wires, cut them out (since I have vac/boost pressure voltage being fed from the ignition switch!), and add extensions, and connect them to the alternator.

Oh, and that connector is definitely required, I had them test my alternator at the local parts store.. 14+ V with it connected, 0 without it.

Trials and tribulations when you have a frankenstein car built from wiring off of 3 different cars.

<sigh>



Thanks for the help guys, I think I've got a handle on what's going on now.

PaulC