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jchaussee Member
Joined: 14 Nov 2010 Posts: 1318 Location: renton
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Posted: Tue Jul 26, 2011 6:41 pm Post subject: messed up electrical |
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| So when I rev car volts are good, as soon as I put into drive they drop. Idles decent also unless I turn on radio, lights, blinkers, etc. Seems to bounce up and down to the beat of my radio, or to the flicker of my blinkers. I want to start with free checks before I start replacing stuff. I am an electrical idiot, but I follow directions well |
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turbo_jimi Member

Joined: 23 Feb 2004 Posts: 1206 Location: Tacoma
1985 Chevrolet Camaro Z/28
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Posted: Tue Jul 26, 2011 6:48 pm Post subject: |
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Did you reconnect that wire you cut from the altenator? You mentioned you did that previously. Also sounds like a grounding problem. _________________
1985 Z28 Crate 350, Hurst T-5, 3.23s, Flowmaster Under previous set-up: 143.82 rwhp 216.98 lbs. torque @4390 rpms 3/12/11 |
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Al Hasse Member

Joined: 19 Nov 2005 Posts: 4379 Location: Bremerton, WA
1992 Chevrolet Camaro RS
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Posted: Tue Jul 26, 2011 6:56 pm Post subject: |
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Problem could be a weak battery, voltage regulator (in the alternator), or even bad grounds - check your battery terminals.
To check the regulator, measure the output post of the alternator (big wire on the back side) with a volt meter or digital multimeter set to DC volts. with the car motor running, you should see about 14 volts. It should stay relatively steady at 14 volts as the RPMs increase. _________________ 92 Camaro
89 Camaro
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jchaussee Member
Joined: 14 Nov 2010 Posts: 1318 Location: renton
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Posted: Tue Jul 26, 2011 7:25 pm Post subject: |
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| I haven't reconnected wire yet, but I did this previous to cutting it. And as far as big wire on alternator, would that be one coming fom my battery. I have several wires connected to my alternator on a bolt . Not a plug like on my truck |
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turbo_jimi Member

Joined: 23 Feb 2004 Posts: 1206 Location: Tacoma
1985 Chevrolet Camaro Z/28
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Posted: Tue Jul 26, 2011 7:44 pm Post subject: |
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I don't think there should be several wires connected there. there are 2 wires connected to the back bolt, a wire going to the positive battery cable, and a wire going into a loom to the auxillary components like guages, electric choke, ect. You can follow this on the wiring diagram I posted in your other inquiry. _________________
1985 Z28 Crate 350, Hurst T-5, 3.23s, Flowmaster Under previous set-up: 143.82 rwhp 216.98 lbs. torque @4390 rpms 3/12/11 |
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Alphius Peanut

Joined: 05 Sep 2006 Posts: 2429 Location: Grand Mound
1984 Chevrolet Camaro Z/28
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Posted: Tue Jul 26, 2011 8:05 pm Post subject: |
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That's standard behavior for an old-style alternator with the reference wire disconnected. If you don't have a smallish two-wire plug plugged into your alt, then that would be why. _________________ 84 Camaro Z28 - LS1/T56
85 Silverado - Low and Slow |
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aaron_sK Member
Joined: 23 Jan 2006 Posts: 8834 Location: Back in beautiful Tacompton
1987 Chevrolet Camaro IROC-Z
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Posted: Tue Jul 26, 2011 8:17 pm Post subject: |
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| turbo_jimi wrote: | | I don't think there should be several wires connected there. |
The one wire that GM put there goes down and connects to all the fusible links at the starter. The thing he has to watch out for is that some moron redneck didn't run something straight off the back of the alternator with no fuse, 'cause that's car fire time when you start getting that stuff.
| Alphius wrote: | | That's standard behavior for an old-style alternator with the reference wire disconnected. If you don't have a smallish two-wire plug plugged into your alt, then that would be why. |
Bingo, Gabe. In his last topic he claimed to have cut those wires. I told them to trace them and connect them correctly. He ignored my good advice and the started a new topic. However my advice remains the same.  |
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jchaussee Member
Joined: 14 Nov 2010 Posts: 1318 Location: renton
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Posted: Tue Jul 26, 2011 8:45 pm Post subject: |
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| It still did same thing before I cut wire, I will put it back, but problem will remain. And it looks as if some redneck wires it because it has three wires connected to a bolt and none of them have fuses. The one I cut is spliced into some blue wire and the fan relay was also spliced into it before I cut it out. I will look at it more closely tommorow and see where all wires are going. I started new thread so I can fix the whole problem, because as stated before, nothing at all changed when I cut the wire. |
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aaron_sK Member
Joined: 23 Jan 2006 Posts: 8834 Location: Back in beautiful Tacompton
1987 Chevrolet Camaro IROC-Z
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Posted: Tue Jul 26, 2011 8:52 pm Post subject: |
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Sounds like it was rednecks vs. logic under there, man.
Time to start tracing wires, kill what you don't need, and run things you do need correctly. Everything needs to have a fuse or a fusable link, and it needs to come from someplace where the sense wire can detect the draw. |
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jchaussee Member
Joined: 14 Nov 2010 Posts: 1318 Location: renton
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Posted: Tue Jul 26, 2011 9:11 pm Post subject: |
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| Ya. I am going to start tommorow. I was also reading up on alternators and they mentioned an " exiter wire"???? I just want to get this damn thing running right |
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aaron_sK Member
Joined: 23 Jan 2006 Posts: 8834 Location: Back in beautiful Tacompton
1987 Chevrolet Camaro IROC-Z
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Posted: Tue Jul 26, 2011 9:17 pm Post subject: |
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Yup.
Exciter wire / trigger wire / ect. Smallest wire. Brown or green usually. Turns the alternator regulator on and off. Connected to ignition switch.
Sense / reference / ect. Larger of the two small wires. Red or orange. Senses amount of voltage being put out by alt, and voltage draw. Adjusts regulator accordingly. Connected to the main lug on the starter solenoid, or other large connector where the alternator power and fusebox meet.
Output. Largest wire off of large lug. Feeds all electrical accessories on car, charges battery. Should be headed for the starter relay.
Ground: Some alternators have a ground strap if they're not grounded to the engine. |
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jchaussee Member
Joined: 14 Nov 2010 Posts: 1318 Location: renton
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Posted: Wed Jul 27, 2011 2:47 pm Post subject: |
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| so it does have a plug. With two wires going into it. A small brown one that is spliced to the brown one that I cut when chopping out my ecm wires. That brown wire goes somewhere towards my driver side. Then the othr plug wire is a maybe 10 gauge or so red wire that loops to the bolt on my alternator. Then on bolt is another wire that connects to possitive side of battery. The battery itself is grounded out on the bolt that connects my alternator to the head. |
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91RSVert Member
Joined: 16 May 2007 Posts: 2736 Location: AR
1991 Chevrolet Camaro RS
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Posted: Wed Jul 27, 2011 3:08 pm Post subject: |
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I'm looking at my diagrams. Not knowing what year you have, I'm going by 90+ since your saying it has 3 wires.
The brown one goes to a fuse panel. It needs 20a.
The red one in the plug should go to some fusible links down by the starter.
The red lug on the back, should also go to some different fusible links, down by the starter.
Also check and make sure all your battery wires have never had corrosion. If they have, Ive seen ALOT lately that the wire was damaged down inside the sheathing due to previous corrosion. _________________ 2008 GMC Z71
1991 Camaro RS Vert
1972 Jimmy 4x4
20ft Longhorn Car Hauler
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jchaussee Member
Joined: 14 Nov 2010 Posts: 1318 Location: renton
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Posted: Wed Jul 27, 2011 3:11 pm Post subject: |
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| Ya. It is obviosly messed up. I don't really need it to match a specific year, I just want it to function the way an alternator does. It is an 85, but has a swapped in 327. But nothing goes towars starter or any fusible links. |
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Al Hasse Member

Joined: 19 Nov 2005 Posts: 4379 Location: Bremerton, WA
1992 Chevrolet Camaro RS
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Posted: Wed Jul 27, 2011 3:12 pm Post subject: |
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| aaron_sK wrote: | | Exciter wire / trigger wire / ect. Smallest wire. Brown or green usually. Turns the alternator regulator on and off. Connected to ignition switch. |
Doesn't that one normally have some sort of resistor or light bulb in the line? I kind of remember seeing some drawings like that. _________________ 92 Camaro
89 Camaro
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Alphius Peanut

Joined: 05 Sep 2006 Posts: 2429 Location: Grand Mound
1984 Chevrolet Camaro Z/28
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Posted: Wed Jul 27, 2011 3:45 pm Post subject: |
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| Al Hasse wrote: | | aaron_sK wrote: | | Exciter wire / trigger wire / ect. Smallest wire. Brown or green usually. Turns the alternator regulator on and off. Connected to ignition switch. |
Doesn't that one normally have some sort of resistor or light bulb in the line? I kind of remember seeing some drawings like that. |
When wired correctly, the stock gauge cluster has resistance built in that triggers the excite wire. _________________ 84 Camaro Z28 - LS1/T56
85 Silverado - Low and Slow |
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jchaussee Member
Joined: 14 Nov 2010 Posts: 1318 Location: renton
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Posted: Wed Jul 27, 2011 4:21 pm Post subject: |
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| Can I then assume that the fat wire that comes out of the plug and loops itself to the lug on the back of the alternator is wrong. ?? |
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turbo_jimi Member

Joined: 23 Feb 2004 Posts: 1206 Location: Tacoma
1985 Chevrolet Camaro Z/28
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Posted: Wed Jul 27, 2011 4:33 pm Post subject: |
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Let's look at the 1985 diagram that is attached and start from the ignition switch.
Yellow wire goes from ignition switch to "clutch start" switch, then purple wire goes from "clutch start" switch to starter solenoid.
Now black wire runs from ignition switch through fusible link into starter (or solenoid...can't tell), then, to positive battery terminal then to altenator (on the back bolt.
Now there is the plug that goes into the altenator with red and black wiring...the red to power and black to ground.
The last wire is brown (or faded tan/rust color from age) that connects to the bolt on the altenator and goes to the automatic choke and the guages(including idiot lights).
It will not look like it's going in any one direction being that it's loomed.
The diagram is pretty explanatory except the brown wire goes off of the page near the lower left, but reappears about 2/3s the way up...it is the only brown wire. _________________
1985 Z28 Crate 350, Hurst T-5, 3.23s, Flowmaster Under previous set-up: 143.82 rwhp 216.98 lbs. torque @4390 rpms 3/12/11 |
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aaron_sK Member
Joined: 23 Jan 2006 Posts: 8834 Location: Back in beautiful Tacompton
1987 Chevrolet Camaro IROC-Z
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Posted: Wed Jul 27, 2011 4:44 pm Post subject: |
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| Alphius wrote: | | Al Hasse wrote: | | aaron_sK wrote: | | Exciter wire / trigger wire / ect. Smallest wire. Brown or green usually. Turns the alternator regulator on and off. Connected to ignition switch. |
Doesn't that one normally have some sort of resistor or light bulb in the line? I kind of remember seeing some drawings like that. |
When wired correctly, the stock gauge cluster has resistance built in that triggers the excite wire. |
This depends on what type of alternator you have. If it is the "older" 10si or 12si then you need a light, resistor or diode or you can potentially have a run-on issue. If he connects the wire as it was stock (which it sounds like it is) then he will be fine.
| jchaussee wrote: | | Can I then assume that the fat wire that comes out of the plug and loops itself to the lug on the back of the alternator is wrong. ?? |
It's not "wrong" per-se since GM actually did wire some of them that way from the factory. It will however cause a dimming problem and is a poor design because the alternator never "sees" the voltage drop. Get a wire of the same color and gauge and run it to the fusable link lug on the starter.
| jchaussee wrote: | | Then on bolt is another wire that connects to possitive side of battery. |
So the alternator is feeding the battery and not the starter lug? That will cause issues because all the juice that the car draws while running has to come through the battery positive wire. Run the alternator output wire down to the starter lug. Make sure to use the same color and gauge. Also note that the alternator hot wire should have a fusable link in it.
Also, if the car will make a distance run, feel free to bring it out to my shop and I can help you with this. I'm off work this week. |
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jchaussee Member
Joined: 14 Nov 2010 Posts: 1318 Location: renton
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Posted: Wed Jul 27, 2011 4:51 pm Post subject: |
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| the positive side of the battery has the wire that splits to the alternator and starter. And as far as fusible links go because I will be installing them myself , for there are none, do I get the kind that have spade fuses, or the twisty kind with the glass fuses, o does it matter, and what guage of wire?? |
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