Ignition switch problems

19stang66 · Aug 28, 2005

When I bought the car the ignition did not work. It wouldn't turn the engine over. But the electrical works when it's in the On and ACC postions. The engine will start right up when I jump the starter selenoid with the key in the ON position. Why will it not start the car? I am completely clueless. I have a wiring diagram I got off the net and all of the wires are there. Would like help asap as I need to get her running before this thursday. Also, is it ok to jump the starter selenoid??

Do all of the wires look right?

65Mustang2+2 · Aug 28, 2005

You ever think of just replacing the ignition switch! maybe $20 if that.

67coupe351w · Aug 28, 2005

You already ruled out the start solenoid. Now you need to find out if the wire traveling from your ignition switch to the solenoid is shorted or if the ignition switch is to blame.

If you have a multimeter checl the voltage between the starting post on the back of the ignition switch and the chassis with the key in the start position. You should be seeing 12 volts there.

If not the switch is bad, if there is voltage your wire is shorted or broken somewhere.

19stang66 · Aug 28, 2005

Ya i saw that they were only $20 but NAPA doesnt have them so I figured I'd try to find the problem with the current switch. I'd have to order it online and it prob wouldnt get here until late this week or next week. I'll try what 67coupe351w said. Thanks guys.

thehueypilot · Aug 28, 2005

The wiring on your starter solenoid does not look right. The two black wires are grounds and should be connected to the screws that attach your starter solenoid!!!!! I don't see your main starter cable on the right side terminal of the picture.

19stang66 · Aug 28, 2005

ummm... ill be right back, gonna go check it out quick, thanks huey

19stang66 · Aug 28, 2005

what two black wires? I only see one small one on the right middle post. The thick black wire on the right side post goes to the starter. With the switch in the ON or ACC position there is about 13v and when I turn it to START it goes to 0v.

Tim65GT · Aug 29, 2005

That's what the voltage is supposed to be at the center post. That is the Accesory power. You need to check at the red/blue wire ( "S" terminal ) It is molded from the switch, so the easiest method would be to penetrate the insulation with a sharp pointed Probe.

Here's a link to a schematic to help.

http://www.hammar.dyndns.org/~djhamma/wiring/1966/66ignit.jpg

Are there clutch safety switches on '66's?

19stang66 · Aug 29, 2005

So what voltage do I need to see at the red-blue wire??? Am I supposed to read 0v at the center post when i turn the ignition to on? Could my readings be off if the starter selenois isnt connected right?

Edbert · Aug 29, 2005

Tim65GT said:
Are there clutch safety switches on '66's?

No.

19stang66 · Aug 29, 2005

According to that diagram Tim posted, all of the wires are connected correctly. I checked the red/blue wire (i think its the red/blue, it has alot of overspray on it) and in the ACC pos. there is 0v, in the ON position there is 12v and in the START postion there is 12v. The red/blue wire is really hot to the touch when you have the ignition on, is it supposed to be that way or does that mean it's probably shorted? Looks like she won't be ready by thursday since mustang depot has some slow a** shipping on my brake lines.

thehueypilot · Aug 29, 2005

19stang66 said:
what two black wires? I only see one small one on the right middle post. The thick black wire on the right side post goes to the starter. With the switch in the ON or ACC position there is about 13v and when I turn it to START it goes to 0v.

The second black wire must be your starter cable which is correct. The little black wire still looks like a ground and if you look at the wiring schematic Tim posted it does not show two wires on that post.

Tim65GT · Aug 29, 2005

What IS that Black wire on the Middle right post?

The brown belongs there, but the black wire, (if it is a ground) could be causing problems.

No wire should be HOT to the touch. Warm is ok. If it is shorted, it would burn up, because that circuit doesn't have a fuse. It's likely going through a circuit that has enough resistance to get it hot.

Check the red/blue wire again with all the small wires on the solonoid middle posts removed. It should be 12V when in the START position.

If not, the wire is possibly shorted somewhere on it's way to the solonoid.

If it's good, check it at the solonoid with it still disconnected. You'll need help (or some long meter leads)

If good, hook up only the red/blue and leave the black & brown off for now.

Try it. If good, then maybe either the black or brown is shorted to ground.

Check for wires taped or spliced to these wires along the paths that look like they don't belong.

krash kendall · Aug 29, 2005

Neutral safety switch.

Bypass it.

Tim65GT · Aug 29, 2005

I seen Hurst Shifter in your signature, and figured you had a stick. Yeah, as Krash says, it's possibly your Park Neutral switch, as you can see in the schematic. Ya still need to find out why your wire is hot.

19stang66 · Aug 29, 2005

the engine wiring is all new. Nothing wrong with that. But as i got to taking the tape off of the dash wiring inside, I found a problem. The yellow wire coming from the ignition switch is melted for as far as i can see so far. Havent got to following it all the way back to the plug though. The orangish wire that was hot looks good so far. Now i'm really confused

krash kendall · Aug 29, 2005

I think that black wire on the solenoid may have been a bypass for some wiring damage in the past.

Tim65GT · Aug 29, 2005

All new engine wiring. hmmm. Then there shouldn't be a black wire at the "I" terminal of the solonoid.

I replaced all my underdash wiring shortly after I replaced all my engine compartment wiring the same problems I found on the engine harness were under the dash.

The factory harness has a lot of splices on the "un-fuzed" Battery power. It goes from Black/Yellow to Yellow. Also on the other firewall plug from Red to the Amp gage, then to Yellow also.

When a wire gets really hot from too much current, it can turn into a "resistance wire". This can only be diagnosed by checking for voltage under load. This can seem like a short circuit.

If your yellow wire was cooked, it might need replacing.

Still, you have to find the cause, not the result.

Tim65GT · Aug 29, 2005

I re-read your post where you said the wire you thought was the red-blue had 12v in the ON and START position. That was probably the red/green wire that feeds the coil through the pink resistor wire. That would be the correct indication.

Go back and check the red/blue (other) wire. It should have 12v ONLY in the start position.

Check it with the other end disconnected at the S terminal on the soloniod.

Did you bypass the Park/Neutral switch yet?

I also noticed from your other posts you had issues with your Amp gage. Did you ever get that figured out?

19stang66 · Aug 29, 2005

Ya i couldnt really tell what wire was red/green and red/blue because there was so much overspray on them. Where and what is the Park/Neutral switch? Is the amp gauge always supposed to start in the middle (all others start to left and move to the right). Now i think the temp gauge isnt working, i turned the ignition to the ON position and it went all the way to H even though the car wasnt on. I'm going to pick up my new ign switch tomorrow at NAPA. Can I use regular wire to replace the melted yellow one. What gauge are the underdash wires?

Ignition switch problems

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