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79 won't start because I'm dumb

1983 Views 8 Replies 5 Participants Last post by  sea dog
This is my first post here, but I'm really looking for some help. About a year ago I bought a 79 TA with a 403 Olds. Most parts under the hood were stock. Got everything running up to snuff and took it on a good 3 hour joy ride. When I stopped for gas the car wouldn't start. I mean at all. No clicking no nothing. A mechanic stopped by and hot-wired the car to start telling me that I'd have to replace my starter, alternator, and probably battery before it would start again. So I did. And it still wouldn't start. Thinking the guy I bought it from might have Jerry rigged the wiring because it looked like a squirrel nest I bought a new engine harness and installed it. And it still won't start.

Everything appears to be connected properly. My battery is fine. When I stick the key in the ignition I get the buzz and the panel comes on. When I turn the key to run the volts zero out. Is this a missing ground or short? And if so how do I go about finding it? I'm dumb when it comes to electricity, and while I learn best by pictures the wiring diagrams might as well be in chinese and I can't find any good pics of the starter and alternator wire connections and where they go on the inter webs. Any help from the community would be greatly appreciated.
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Check your neutral safety switch. Make sure the shifter is fully engaged into park. if it still wont start, put the shifter in neutral and try it. if it still wont start, hold it in start position and move the shifter from park to L and see if it tries to start in any position.
ok. tried that. still nothing. when I put hold the key and start shifting the buzzer dies out. down to zero on the gauge. When I let go it's back to 12.
Sounds like the ignition switch is all that is left. I know on my '71 the purple wire from my ignition switch goes to my starter "S" terminal. When I turn the key all the way to the start position, the purple wire goes hot, which makes the "S" terminal go hot on the starter solenoid, and the starter turns over. I would verify your starter wires are connected good, then see if the "S" wire goes hot when you turn the key all the way to the start position. If it was, the starter would be working, since it is not working either the ignition switch is bad, or is not getting any voltage, because the neutral safety switch, or the switch needs moved toward the key so the link rod between the key and the switch pushes the ignition switch all the way to the end of its travel. Start at the S terminal of the starter and trace your way back until you get voltage to see why it is not making it all the way to the starter.
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Just replaced the ignition switch and still nothing. Everything is tight as can be on the starter. Looks like I'm missing a ground somewhere. Is there an extra wire or something that comes off the starter for a ground? I have the purple that goes to the ignition, the fat red that goes to the battery, and two others that are bundled that connect to the main post on the starter as well.
Have someone hold the key in start position. You should have 12v @ the purple wire. If you do have 12v there in start position, then suspect starter. If you dont then look for 12v on the input side of the neutral safety switch, believe its a blue wire. It will be a heavier gauge wire.

also, the purple wire going to the starter, goes to "S" on the starter solenoid, not "I"
No the starter is grounded to the engine thru the mounting bolts

I would check the ground straps between fire wall and the engine usually bolted on the

head some where .

I added extra straps on mine you can never have to many grounds
It is a very simple circuit this might help

Schematic Font Slope Rectangle Parallel


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When you turn key to start position and voltage drops to 0, it can be 3 different problems. (1) there is a bad connection on battery cables, ground strap from engine to firewall, major power wire to ignition switch. or

(2) the starter is bad and it's drawing major amps over what it should draw that's dropping voltage to 0.

(3) battery is bad and high amp load from starter trying to work is dropping voltage.

Now for tests. You need to have assistant turn key to start. Use multimeter or test light to check voltage on purple wire at starter solenoid with the purple wire disconnected from starter.. If you have 12 volts there with key in start position, ign sw is doing it's job. If voltage drops with wire disconnected, battery or ignition switch problem.

For next test put purple wire back on starter.

Next put multimeter on large battery cable at starter. It should have 12 volts all the time. Have assistant turn key to start. Does voltage drop to 0. If yes unhook the cable from starter. But first unhook the positive batt cable. Once you have cable off starter, and in a place where it won't hit metal, hook the pos cable back to batt. Have assistant turn key to start while you check voltage.

Because cable is unhooked from the starter (load) voltage should stay at 12 volts. Does it? If yes, either starter or battery is bad. If voltage drops with cable off starter, then battery, or cables bad.

Take battery to a place that can test battery with a load on it. You can do it yourself as places like harbor freight sell these type of testers. If battery is good, starter is the suspect.

If battery is bad, starter could still be bad, so take it off and take it to an auto parts store that tests starters. Autozone, advance, etc.
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