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Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Electrical> an outside set of eyes would help!!
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Topic Review (Newest First)
03-22-2009 06:58 PM
66chevroLET okay......i'm a ******* after taking the schematic and cutting open the wire loom and everything to check connections.......i finally broke down and had the alternator checked, and guess what. i found out why the hell my generator light was on..... don't i feel like a damn moron.....hahaha.

thanks anyways for the info though, mikey
03-19-2009 03:46 PM
66chevroLET alright. i ran a wire from a terminal on the fuse box that only gets power with the switch on to the #4 terminal on the regulator(the one reading out to 5.4v before) with that wire in, i get the 12v on the wire there, and since the generator light is getting it's 12v from the other side, it goes out like it's supposed to when the engine starts running. i still only get 12.5v at the terminals on the back of the alternator, so i'm going to go have it checked out. now, if that light is grounded somewhere it shouldn't be, can i leave the #4 terminal hooked up the way it is and still have my battery charge? (since the light is obviously getting the 12v from both sides like it should be).

03-17-2009 05:22 PM
66chevroLET Thanks mikey. that schematic and the info are awesome. i turned everything on, and the #3 terminal reads at 12.4v. the #4 terminal only reads at 5.4v.

so i'm guessing that either the regulator has gone bad, or i'm going to have to chase wires and find where the light is grounding?

speaking in terms of being lazy, if it isn't the regulator going bad, will the alternator charge if i leave the jumper from the battery to the #4 terminal, even if the light is grounded?
03-15-2009 06:56 PM
powerrodsmike You should have 12v power at the regulators 3 and 4 terminals in order for the alternator to work, with the key on, and the motor not running... terminal 4 is you excitor terminal..Without 12 volts being supplied to that terminal, the alternator will not charge. Terminal 3 & 4 should be connected to 12 volts from the accessory side of the ignition switch. The idiot light wired inline in the wire that goes to the #4 terminal...

Try taking a jumper from the battery + terminal and jumping to terminals 3 and 4 onte regulator while the motor is running.....if the voltage comes up to 13.5 or more, you know that your idiot light is grounded somewhere or not hooked to the right place..

You will need to learn a little about schematics if you want to straighten out your charging systems problem .

When you wired in the toggle switches we have no way of knowing what you left out.

Here is a schematic for your charging system.

It may be because you disconnected the ignition side of the idiot light circuit and current is backfeeding through the resistor , to the switched side of your idiot light...The resistor is there in case the light burns out, the alt will still get the excitor current and then will charge.

Later, mikey
03-15-2009 06:14 PM
66chevroLET i'll check out the 3 and 4 terminals. if i get power there is it a good or a bad thing?

also, is this just going to be that the alt/regulator has gone bad? or is there something else i need to do with that green wire that's still under the dash?

i'm sorry guys, but this whole charging and electronics crap just doesn't seem to click in my head

by the way, it does die when i take one side of the battery off....

03-15-2009 04:31 PM
Originally Posted by snod83
Why not start the car and pull a battery cable to see if it dies? Should work on a 66 right?

Maybe not though....
It works, I've done it so many times on older cars I can't count them all.
I wouldn't do it on any car with a computerized anything on it...
I did it one time on my Mom's 91 Mercury Tracer stayed running, but as soon as we shut it off and turned it back on it wouldn't idle below 1500 RPM and the check engine light came on... I couldn't figure out what was wrong and we had to take it to the dealer.. I'm sure they spent about 4 seconds fixin it, and charged us 150.00.

I don't even open the hood on new cars now.

Later, mikey
03-15-2009 03:25 PM
snod83 Why not start the car and pull a battery cable to see if it dies? Should work on a 66 right?

Maybe not though....
03-15-2009 11:22 AM
powerrodsmike Do you have power at the regulator at the 3 and 4 terminals with the key on and motor not running?

Get your alternator out and checked out at a parts house. They will usually do it for free.

03-15-2009 11:13 AM
66chevroLET yes with the motor at idle, it jumps between 12.4-12.5v on the multimeter. as i turn stuff on, like headlights, high beams, wipers and turn signals, it drops to about 10.5-10.8v.

and no, it doesn't stay running after i flip the switch to the off position.

i don't know if it has anything to do with it, but i took the old switch apart, and noticed that when it is turned to the "start" position, it connects the bat, sol, and ign terminals (momentarily disconnecting the accy terminal). when it's returned to the run position after it starts, it reconnects the accy post. with the toggle switches and the push button, that momentary disconnect does not happen.

but i am hoping that all this is is that the alt/regulator just happened to decide to take a **** when i decided to take out the key switch.
03-14-2009 08:39 PM
powerrodsmike Do you have a voltage regulator installed? With a 12.5 volt reading with the motor running the alternator is not charging.

answer that and we'll go from there.

I drew a picture, you will need to trace some wires, I don't know GM color codes. The idiot light wire may come from a buss in the fuse box, the important thing is that the side that goes out to the motor needs to be hooked to the regulator as shown.

The diode may not be necessary with an external regulator, if the car runs on after you shut the key then you need a diode.

Later, Mikey
03-14-2009 08:27 PM
an outside set of eyes would help!!

hey guys. i'm brand new here, but i plan on sticking around for a while, but anyways....i don't know if there is already a thread on this or not, but i need an answer as soon as possible.

i have 66 caprice 4-door hardtop. i decided to be "mr. electrician" and go ahead and try to wire in a push button start system with 2 switches and the button. i have everything wired up and mounted and the car starts and runs fine. i'm getting just over 12v on the voltmeter at idle with no lights or anything on, but my generator light stays on after i start it. there is one green wire that i have no clue as to where to put it. on the old switch, it was connected to the "ground terminal" now, when i flip the switches, the hot light comes on when i ground this wire. when it hangs loose, nothing. in both cases, the generator light stays on. i looked at a few older GM wiring diagrams(not caprice/impala specific), and this 5th wire runs from the switch to the temp. sens. on the intake manifold. makes sense, but why on the ignition switch. also, when i pull the accessory wires away from power, the generator light gets real bright, but as long as the accessory side stays hooked up to power, it only glows.

i don't have a generator in there. it's an externally regulated alt. i don't know crap about electronics, and i don't know if that light is for real, or how to check to see that the alt is charging the battery. but i do know that this generator light was not on when i disconnected the battery to do this mod. i do know that on the multimeter, i was getting 12.5 at the battery and the terminals on the alternator at idle. i also know that the engine dies when i disconnect the battery. i just don't want to assume it's okay, and go try to drive somewhere and get stuck!

i know this is a lot of crap and if anyone feels adventurous enough to help me out, it would be immensely appreciated.

thanks in advanced

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