delco alternator wiring question

[notothisrealm]

Hey guys, its me again. Im trying to figure out how the previous owner routed the wiring for the alternator. Im reading below 12v and even less when the car is on and lights are on. Did the dude before know what he was doing? The red arrow is the thick wire coming from the alt and the green is the thin. The thin wire is also spliced into another pink/white stripe wire. The alt is a delco series 10.

Edited September 16, 2015 by notothisrealm

[malibud]

if no one responds I can look t mine but the PO put mine in and I am no expert 

[notothisrealm]

Please, man. I would appreciate it. The alternator isn't charging, but it test ok.

[NewZed]

Hey guys, its me again. Im trying to figure out how the previous owner routed the wiring for the alternator. Im reading below 12v and even less when the car is on and lights are on. Did the dude before know what he was doing? The red arrow is the thick wire coming from the alt and the green is the thin. The thin wire is also spliced into another pink/white stripe wire. The alt is a delco series 10.

You have a picture of wires hanging in space, in an unidentified car, in the Miscellaneous Tech sub-forum.  Reading below 12 volts, but no indication that the engine is even running and the alternator spinning.  Pretty sure "the dude" knew more than you, but his work looks pretty shoddy.

 

Describe the car, the engine, and what the voltmeter or ammeter does with the engine off, idling, and revving.  Those will be good clues.  No Carnacs out here.

[notothisrealm]

Ok. The car is a 71 240z running a sbc 350 with a th350 tranny. I have a volt meter wired in to the thick white wires that were on the ammeter. I put them together with the power wire to the volt meter. The volt meter is always on even with the car off. It reads just below 12v and then drops to about 8 to 9v when the car is on. A bit lower when i turn the lights on and the electric fan slows down as well. I haven't noticed what it does when I rev the car, I will get back to you on that. I put a multimeter on the battery with the car off and it reads 13.7-8 and 10.3-4 when the car is running,if that info helps.

[NewZed]

That does help.  The delco alternator is internally regulated alternator so the 1971 external regulator doesn't need to be considered, although its old wiring might.  The 8-9 at the dash meter, with the 10.3 at the battery shows that dash meter is wired incorrectly or you have a big voltage drop between the meter and battery.  The 13.7 with the car off, assuming that the meter is accurate, would show that the alternator does charge.  Unless that reading is right after removing from a charger (is the battery on a charger).  The 10.3 when the engine is running is undefined since you didn't specify idle or revving.  The alternator might just need more speed to charge or it might not be charging at all.  Sometimes people wire their alternators in "one-wire" fashion and they have to be revved to start charging.

 

The good news is that unless you touch wire ends to the wrong spots, all of those problems are fixable.

 

Here's a link about the 10 that might help - http://bob_skelly.home.comcast.net/~bob_skelly/alternator_conversion/wiring_alternator1.html

 

There's a lot more out there on the CS130 though.  Have your alternator tested and if it's bad, consider that route.

[notothisrealm]

Ok, so, i got a multimeter and noticed that the battery is putting out 11.60v when its completly off. When i turn the key to acc the voltage begins to drop slowly. When i turn the car on it drops quicker. I revved it up to see if the alt. would begin to charge, and nothing. Volts still dropped, and faster. I got the alt. checked and its good. I disconnected the volt meter to see if that was the issue, it wasn't still got voltage drop while the car was on. I left the positive on the battery and checked it later to see the battery is still at 11.60v. So it isn't draining the battery when the car is off only when its on.

[NewZed]

Disconnect the alternator and see if the same happens.  Alternators have been known to short internally.

 

11.6 is low charge.  Get a charger on the battery or you'll really get lost.

[notothisrealm]

I got the alternator tested and it passed. Im fresh out of ideas and it sucks because I really wanted to take the car to JCCS tomorrow. Oh well, thanks for you help. I appreciate it.

[NewZed]

Don't make it complicated.  The internally regulated alternators only need four wires.  One to energize the windings (The "L" wire, "L" for Lamp), one to Sense the voltage level ("S" for sense), the big thick wire that carries the charging current, and ground.  Ground is often through the case so there may not be an actual wire.

 

"S" is easy, it can just go the battery positive terminal.  The charge wire is easy also, it typically connects to the starter solenoid lug, (after running through the fusible links), which is connected to battery positive.

 

L is the one that needs to be defined.  It is just a wire that is only hot when the ignition switch is On (aka Run). 

 

If your alternator is good but it's not charging in the car, that's an L wire problem, or the charge wire is not connected to anything.  Confirm the charge wire, then find L.  Use a meter.