65 GTO electrical questions

scott06

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Getting down to electrical and interior on my 65 convertible resto and have a couple of issues I'm chewing through.

When key is in off position battery light comes on. Battery light will be off in the run position when engine is running or not running. This is a new issue as my resto is going on 30 years now (bought it in high school and n ow just getting to a point where $$$ and time are available...) the wiring was done enough to have it running years ago, and just recently started. One thing that also recently started was when I reconnect the positive battery cable (i leave it off when I'm not messing with it) I get a audible and by touch noticeable click from voltage regulator. Only think I added was an electric choke for the edlebrock carb I'm now running disconnecting it makes no difference. Any ideas on what to chase down?

My car is a convertible with power windows - was there a ground wire for the door window motors or is the chassis the ground through the hinges? Motors only have two wires going to them, I haven't dug into door harnesses to see if there is a ground wire in there that need cleaning of connection etc. My drivers door only works when i jumper a ground to the chassis.

The car has rally gauges with the tach- when I bought the car in 1990 it was typical of a car taken apart - there were wires hanging out of the dash and lots of parts in the trunk. I didn't see any tach lead to coil in any of the harnesses (my dad and I rebuilt my harness with u-pull it parts off old GM cars) and I haven't been able to find a repro tach harness except for Transistorized ignition cars. My car originally had TI, but except for the amplifier below drivers wheel well all other parts were long gone. I ran a wire to make the tach work but Bottom line what did the factory wiring look like or where can I buy it without hopefully having to buy a whole harness. Car was originally 3x2 bbl/ 4 spd/TI , currently I have a non matching 4 bbl and 4 spd with points style distributor....
 

melsg5

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Oldest manual I have is a 69 Chevy shop manual. It states under the section concerning the indicator lamp a shorted positive diode may also cause glow with ignition switch OFF.
Recommend you look through the 65 Pontiac Chassis Service Manual to verify this and follow the generator test instructions in the manual.
Concerning the window, 70 Pontiac shop manual shows the power window motor self grounding. I would think the hinges act as a ground, did you paint the hinges?
Concerning the tach, aftermarket sells tach wiring harness.
 

scott06

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I must have painted the hinges as I had the whole car apart for blasting and epoxy priming. I see if I can take a bolt out on each side of the hinge and get a path to ground.

Will test the alternator /charging system - do you know if the diode is in the alternator right? I spent some time with this last night and determined the indicator light goes off when I disconnect the two wire plug from the alternator (only other connection than the big wire/12+ V lug). I have another alternator that I took off a couple years ago because it has bad bearings so I can swap that back on and see if it goes away.
 

melsg5

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Yes the diodes are in the alternator.
Do you have the 65 factory manual?
Have you tested alternator AC voltage output with running engine, large output terminal?
You can also test output by setting multimeter to DC voltage and testing output, you should have 0.
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scott06

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I have a 66 factory manual assume that is similar for charging system diagnosis, but have yet to go through testing the alternator output.

Battery cables were not reversed, I did replace the original alternator on it with a rebuilt unit two years ago. The original which was off a parts car 65 I had years ago was only a 37 amp alternator and had bad bearings, so I upgraded to a higher output reman. I suspect I would need more than 37 amps for a car with a lot of accessories like power seat,windows, and top?
 

scott06

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Just to close the loop - it was the alternator. I may be using the wrong term but the one of the what look like two brushes in a dc motor was broken. Also had chafing on the wire to capacitor in back housing.

Also yes you can upgrade the output of the alternator but it can become cost prohibitive for the parts unless you are doing a numbers matching rebuild.

I know you said the tach harness is available aftermarket - the only ones I can find are for transitorized ignition - if anyone knows what vendors sell them for a standard ignition that would be great- or is this part of a the rally gauge harness? Its hard to tell what should be there when you buy a car that someone else took apart. thanks
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