Alternator replacement - wire advice

D

dnaze

Daily Driver
I just replaced my stock '74 44A alternator with a 65A I had from an A/C equipped '86. Because the 65A has an internal regulator I connected the purple/black to the single male plug (not one of the triples) and left the connector to the OE voltage regulator unplugged. Now I have no charge light on the the dash so I'm a little hesitant to fire it up.

Am I connected to the correct male outlet on the alternator, or should I leave the plug connected to the regulator even though the white wire does not connect to anything at the alternator?
 
All I know about the early alternators is what I have seen in the Wiki, specifically the alternator wiring diagram for the '76. On the replacement alternator you should have two connections, one fat wire to the battery (listed as black in the '76 wiring diagram) via the starter and one skinny wire to the instrument cluster (listed in the '76 diagram as Black/Violet to the voltage regulator and red continuing to the alternator). Is this how you have it connected?

The fact that the alternator light isn't working is a problem, if this circuit does not work, the alternator will not generate any output. Did this circuit work before you removed the original alternator? This circuit is easy to test: Ground the black/violet wire with the ignition on and the engine not running. Does the alternator light come on? If it does not I'd check the bulb first, then the wiring to the bulb.
 
Thanks, but....

When I gnd the purple/black, the light goes on, but stays on when engine starts.

The '74 has no red wire, so differs from the '76. I also looked at the '86 schematic which is just a 2 wire deal. I'm curious if I'm connected to the wrong terminal on alternator? There is a single spade in a plastic protector, and than 3 on the brush module.
 
Perhaps you can post a photo of your connections. Also, is your 65A alternator a Bosch or a Marelli? I know Bosch was used in 86, not sure if they used Marelli as well.

Not having seen the alternator, I would say that Black/Violet on a spade terminal sounds right. Not a whole lot of current going through this circuit, just the dual purpose of turning on the alternator light and supplying a bit of current through the rotor before the alternator starts generating its own rotor current.

The actual output from the alternator goes to the fatter of the two wires. There should be a single output terminal for this wire, typically a stud insulated from the alternator housing. Having the fat wire connected to the wrong place could cause some real damage, so I'd make sure this is correct before proceeding. I'd also disconnect the battery negative while working on this, you probably did that already.

Lastly, on mine the alternator light does not go out until I rev the engine a quite bit above idle. There is even a spec for it in one of my Fiat manuals. I have noticed the same thing on two other Italian cars of similar vintage.
 
As Bjorn says...

First though...

Ya need to completely eliminate the OLD regulator from the circuit.

The alternator SHOULD be charging the battery with just the one LARGE lead connected to the starter post containing the LARGE positive cable from the battery.

If you measure the voltage at the battery (I place my voltmeter upside down on the windshield so I can see it from the driver's seat...) is should read about 12.6. Start the car and rev it a bit and you should see about 13.8 volts or greater. This will mean the alternator is working.

The second lead on the alternator SHOULD be just for the dash light and voltmeter on the dash... This usually goes to the ECM on later models and then is connected to the dash indicators.

If the alternator did NOT show an increase in voltage, then this second lead is probably a necessary teaser to trigger the alternator to work. In either case, we'll get it to work...

Using a '74 Euro and NA schemaic... I find that...

The Brown lead goes to the starter.
The Black/Violet lead goes to the dash guage.
The Red, White, and Black/White leads are now discarded with the Regulator.

I believe all you need to do is locate the existing Black/Violet lead and tie this to the other lead on the alternator.

Having said all this and re-reading what Bjorn just said... we AGREE!

Back to the voltmeter readings... If there is NO increase in voltage, there is a good chance the alternator is defective.

If there is no increase in voltage, I'd take it to a reputable tester and have it checked. If it proves to be defective... then we have our answer.

I would also recommend that you opt for a GM conversion.

http://www.network54.com/Forum/12159/message/1142890167/GM+alternator+conversion

Also note my 2008 update...

Good luck... hopefully we've been of some help and not confused the crap out of ya!
 
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