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HELP! Should the volt meter on a '76 280Z be ON when the car is OFF


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I performed the CS144 GM alternator conversion on my 1976 280Z.

 

I eliminated the external regulator by wiring together two pairs from the ER per this guide: http://www.atlanticz.ca/zclub/techtips/alternatorswap/index.html

 

What I am not sure about is that even when the key is removed, the voltage gauge on the car is always showing the battery voltage even if the car is off.

 

I came out this morning and the battery was nearly dead, like it's been slowly drained. I didn't notice any of the lights or anything having been left on.

 

The thing is, I have disconnected the alternator from the battery (I ran a 4ga wire directly from the alt to the battery), the wiring harness from the alternator, and short of disconnecting the ground from the alternator, it is effectively out of the electrical look (at least positive-wise, it is still bolted in, thus grounded).

 

I'm about to pull my hair out over this.

 

Please help. :/

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I came out this morning and the battery was nearly dead, like it's been slowly drained. I didn't notice any of the lights or anything having been left on.

 

The thing is, I have disconnected the alternator from the battery (I ran a 4ga wire directly from the alt to the battery), the wiring harness from the alternator, and short of disconnecting the ground from the alternator, it is effectively out of the electrical look (at least positive-wise, it is still bolted in, thus grounded).

 

I'm about to pull my hair out over this.

 

Please help. :/

 

I'm confused. Did the battery discharge overnight with the alternator disconnected? In either case, I don't think a diode is going to solve that problem. The diode is typically to prevent the engine from continuing to run after the ignition is shut off

 

Also

 

Nigel

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I'm confused. Did the battery discharge overnight with the alternator disconnected? In either case, I don't think a diode is going to solve that problem. The diode is typically to prevent the engine from continuing to run after the ignition is shut off

 

Also

 

Nigel

 

No, I did all the disconnecting today.

 

What happened was last Thursday I did the 280Z Alt swap to the CS144 GM swap.

 

It sat for about 8 hours (I finished at 3am Friday morning) and started up for lunch just fine.

 

Went out Friday, and parked it from about 2am Saturday morning until 10am'ish (another 8 hours or so). Then after getting home about 10:30am saturday, it sat until 5:30am this morning (Monday; ~43 hours). The headlights were barely able to turn on and the car didn't bother trying to start. I'm pretty certain I didn't leave the running lights on or anything.

 

I have it charging now; it seems to be taking the charge. The lights are all coming back on, etc. I'm going to try starting it in a couple minutes.

 

I hooked up the old T connector from the F and N wires from the old alternator to the S and L leads on the CS144 alternator. The S lead now has a constant 12v and the L is on a switched 12v which is what it should be AFAIK.

 

I did not connect the old battery wire (white'ish) because I ran a new 4 awg wire from the battery post directly to the battery. I also did not connect the old "E" black wire and instead grounded the battery to the engine block with another 4awg wire.

 

The external regulator was bypassed per the instructions from the link in the first post (5 to 1, 3 to 2, 4 and 5 not used).

 

I have a 100 ohm resistor inline on the "L" wire per some instructions from another guide, but now I've noticed that the little red light on the dash doesn't light up or does just faintly. Is that an actually light bulb or is it just an LED? Nigel, should I leave the resistor in? I put it in because there was one in the harness KTM used in this post (http://forums.hybridz.org/showthread.php?t=135557&highlight=cs144) but I just went to the scrap yard and cut out the connector instead of buying one from NAPA for $20.

 

The other thing may be that the battery has just reached it's limit. It was in the car when I bought it (Duralast Gold; no date of install on the battery :fmad:). I did die on me Thursday before I started everything, but I'd contributed that to leaving the running lights on for a couple hours.

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I hooked up the old T connector from the F and N wires from the old alternator to the S and L leads on the CS144 alternator. The S lead now has a constant 12v and the L is on a switched 12v which is what it should be AFAIK.

 

That's what I did.

 

I have a 100 ohm resistor inline on the "L" wire per some instructions from another guide, but now I've noticed that the little red light on the dash doesn't light up or does just faintly. Is that an actually light bulb or is it just an LED? Nigel, should I leave the resistor in? I put it in because there was one in the harness KTM used in this post (http://forums.hybridz.org/showthread.php?t=135557&highlight=cs144) but I just went to the scrap yard and cut out the connector instead of buying one from NAPA for $20.

 

Some means of limiting the current going into the charging circuit is required, which can be accomplished with either a light bulb OR a resistor. Both are not required, so you can eliminate the resistor.

 

So is the battery holding a charge now?

 

Nigel

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That's what I did.

 

 

 

Some means of limiting the current going into the charging circuit is required, which can be accomplished with either a light bulb OR a resistor. Both are not required, so you can eliminate the resistor.

 

So is the battery holding a charge now?

 

Nigel

 

 

I charged it up, started the car, with nothing on, it charges at 13.6 or so, if I have the cooling fan, AC, radio and headlights on, it charges at 13.9-14.2.

 

I let it run for a bit, disconnected the negative from the battery and noticed it fell to 12.7'ish. I'm going to check in about a half hour or so and see if it's continuing to fall. If so, I need a new battery. If it doesn't drop, I'm going to reconnect the negative and then check it again later to see if it starts dropping there. If it does... then I'm SOL as I don't know what I could have messed up since it seems like everything is correct.

 

That red CHG light is a bulb and not an LED? Okay, I'll removed the resistor then.

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There's a brake warning lamp check relay under the passenger seat seat that will stay powered up incorrectly if you use the atlanticz.com approach without a few wiring mods. I think the problem is unique to the 1976 Zs. Here is a link - http://www.classiczcars.com/forums/showthread.php?t=36480

 

 

Zed, you are most excellent! I found that relay under the front passenger seat brace. I had originally cut "a" yellow wire near the door and found nothing happened; I was still getting the relay click. Eventually found it and when I cut THAT yellow wire, it stopped throwing the relay. My "Brake" light on the dash stays on, but the relay is no longer heating up (it was warm-hot before) which makes me assume there's no longer current through it.

 

A picture for prosperity!

IMAG0034-1.jpg

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Glad it worked for you (so far). Be careful with those cut "hot" wire ends, they're fuse-blowing time bombs.

 

The connector with the fuel pump wire is under the carpet along the edge of the rocker panel, at the bottom of your picture, out of frame.

 

I threw some tape over it. Do you happen to remember off hand which wire is the fuel pump wire? Id originally cut a yellow wire coming out of a rectangular connector on the door side of the passenger floor pan. Does the wire go through that connector as well?

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It looks like the green/blue wire right between red/white and black. Stick a voltmeter probe down behind the wire and see what it shows with the engine running and not. You never know, a previous owner could have rewired your fuel pump. My car had an old wire run the length of the car next to the brake lines to bypass the AFM switch.

 

Tried to add a picture from the FSM but the file was too big.

 

http://www.xenons30.com/reference.html has the 1976 FSM available for free download. You should get it while you can. It's good reading. Page BE-7 has pictures.

 

Good luck.

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  • 3 weeks later...
Hmm. My 76 does NOT have that relay. Cali models only?

 

Possibly. I noticed my Z also has that damn phase timing, so there is a 5º difference in timing between a cold engine and a hot engine. As far as I understand it, this means it's pretty much a CA car.

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