Alternator??Or Crossed Wire?

[awolfe]

I have a 77 280Z with an 82 model alternator, prior to rewiring a complete mess of things i had the charging system working great(alternator producing 13.85-14.00V). Now after correcting many mistakes (previous owner) in the wires under the dash the alternator only puts out aprox 10.00-10.50V. Could the alternator died all of a sudden? Could i have cross some wires that would have this effect? I followed the wiring diagram exactly as it showed with just a few changes due to having automatic wiring harness with a manual trans (again previous owner). Or could the wire harness be the problem?

Thanks in advance!

[FastWoman]

Maybe your S terminal (voltage reference) isn't correctly wired or has a faulty contact??? Dunno.

[awolfe]

Took alternator to advanced auto for testing, they said it was bad. Picked up a new one and gonna double check ever wire before connecting. Cross my fingers its just a bad alternator.

Considering none of the wiring was done in the engine compartment and just under the dash I should be fine, Right?

BTW, You guys and gals rock with your fast responses!!!

Edited February 19, 2011 by awolfe

[Zed Head]

I think that internally regulated alternators can be damaged if they get more than ~3 volts on the L wire. The L wire is the wire that goes to the lamp in your voltmeter. You can check it at the T plug before you connect the alternator by turning on the key and measuring. If you get battery voltage, you need to rewire to the voltmeter lamp or put a resistor in line.

The other wire is the S wire and should measure battery voltage.

[awolfe]

I think that internally regulated alternators can be damaged if they get more than ~3 volts on the L wire. The L wire is the wire that goes to the lamp in your voltmeter. You can check it at the T plug before you connect the alternator by turning on the key and measuring. If you get battery voltage, you need to rewire to the voltmeter lamp or put a resistor in line.

The other wire is the S wire and should measure battery voltage.

Can this be confirmed? Cause my L wire is getting battery (12+V) voltage, not sure where from?

I got the same results with the new alternator as with the old. I have to be missing something, most of the wiring i changed went to headlights, heater, turnsignal, hazzard, etc...(under the dash). I did though take all the wires that were cut, twisted, & taped coming in from the engine compartment and changed them to butt connectors.

Any thoughts would be helpful.

Here is the wiring diagram that I have been using.

77_ZCAR-WIRING.pdf

[Zed Head]

By your wiring diagram the wire from the lamp is the blue one at the harness plug to the regulator. By the 1982 diagram, this wire should connect to the bottom of the T switch, identified as L.

The atlanticz swap page shows the same thing. Blue wire from plug connects to the bottom leg of the T plug. Blue to white wire w/black stripe.

Here is the link that I looked at that said explicitly that the Lamp circuit needs less than 3 volts. It is for a GM alternator. I got curious and measured the voltage on mine and I got 2 1/2 volts,to confirm the same on the Z. The blue wire is after the lamp on the power circuit so it should not have 12 volts since the lamp is a resistive element. If you're measuring 12, you must have it hooked up to the battery or a switched 12.

http://www.hotrodlane.cc/ONLINETECH/CS130DREG.html

Here is the atlanticz page for reference, look down at the bottom to see 1977. http://www.atlanticz.ca/zclub/techtips/alternatorswap/index.html

When I did the alt swap I ended up with one extra hot wire and one extra switched wire. Your original swap may have been done incorrectly. Might be worth pulling apart the splices under the hood to see what the PO did. Just follow the wires from the alt, there should only be four or five, S, L, power (B+), ground (E) and maybe a capacitor wire.

Edited February 20, 2011 by Zed Head

[awolfe]

Here is the atlanticz page for reference, look down at the bottom to see 1977. http://www.atlanticz.ca/zclub/techti...wap/index.html

Yeah, thats the setup i used when i got the car and it worked like a charm. After looking at the diagram i realized that i tested the yellow wire thinking it was the lamp. I was having problems with the headlights shorting out and heater motor not working, so thats when i started tracing and rewiring under the dash. I have noticed that the gauge lights are no longer working, so maybe i got a wire or two crossed with each other. I guess I'll be back to the floor board on my next day off to go through the wires again. Thanks for the help.

[awolfe]

Ok, so i could not wait til my next day off and dove into the wiring this morning. I did find one green wire that is connected to the lamp light on voltage gauge crossed with the drivers side seat belt switch. Got that fixed, charge light comes on with key turned. I have not tried to start the car yet til i am 100% sure all other wires are correct.

I am finding that many of the old harness connectors have shorts and have to be wiggled to get proper connect. Has any one else had this problem? If so, how did you solve? I have looking for OE style replacement connectors, but have had no luck. Would you suggest cutting out connectors and replacing with single terminal connections?

(Refering to connectors like C-1, C-5, C-6, and even headlight combo switch)

[SteveJ]

For a lot of connectors, you can find them at Vintage Connections. Some of them may not be exact, but they are as close as you can get. If the connector bodies are intact, you can remove the wire and put on a new connector (provided you have some slack in the wire).

[awolfe]

The green wire was my problem, Everything double checked and fired up. Alternator output ~14.5V. Runs 10x's smoother.

Thanks for all the help!!