I need help! Starting the Javelin:

Okay, this thing has thoroughly confounded me. It's an AMC Javelin which uses a Ford 5-post starter solenoid on the fenderwell, and a GM column with ignition switch.

• New battery, tests good with 12.5V and will start the starter on the test bench
• New starter, tests good on the bench
• New solenoid, fresh out of the box, correct for the application
• New battery cables
• New Ignition Switch

Here's what happens: Hook everything up how it's supposed to go, and when you turn the key to "start" nothing happens. Leaving it in "run" and then attempting to use a remote starter switch does nothing. Once investigated (with key to "run"), there's 12V to the solenoid (direct cable), and 12V on both the I and S posts! How can that be? I thought the S post stayed off until the key was turned to "start" and that a remote switch worked by keying 12V to that post?

Could it be the 5th post (neutral safety switch)? Is that supposed to have 12V, 0V, or something else?

For completeness sake: Cable goes from - terminal on battery direct to engine block, secondary cable goes direct from - terminal to frame. Cable goes from + terminal to solenoid. At the other end of the solenoid a cable goes directly to the starter.

When I touch a spare battery cable from the + terminal to the starter cable, the starter will turn and the engine will try to start (and the cable will try and weld itself). So if you complete the circuit, it will work.

Did you connect the Neutral Safety Switch post to anything?

I would guess that that's your problem but I have no idea if that is supposed to be grounded or hooked up to 12V.

I don't know if it's supposed to be 12V or 0V either. The issue I have is that the remote switch instructions say it doesn't matter if it works or not, and the "S" post shouldn't have 12V in "run" anyways.

Sigh I berkleying hate electrons.

I would be surprised if it wanted to enable high; tie that thing to ground and see what develops.

The 5th post? I think you're on to something there. I have a factory service manual for 74 with diagrams (my 73 Javelin should be identical), and it is also saying that the solenoid is grounded through the neutral safety switch, which is the 5th post.

So that would explain how 12V is getting to the S post and not causing a start condition.

Seems more straight forward to just offer the solenoid a ground through the shifter vs. trying to safely feed 12VDC+ through it and not have problems as components age. So yeah, get one of your old batt cables that you pulled out of there and use that as a ground wire "jumper" between the post and something good like that negative post on the battery.

16ga would probably be enough but I'd go big first to see how it goes.

Since a 70s starting system is as simple as it gets I doubt you could figure out the following swap. However since its just too cool not to share, I'll say your problem is that it needs more of this:

Mother. Of. God. Does that intake say "Aston Martin" on it?

Everybody has their automotive weakness. I know mine is electrical systems, and I am making a serious attempt to be better at it.

Thanks to pres589 though, I have a solution! I checked for grounding at the 5th post, and there was none in the wire with the ignition on! So I made a direct connection from a spare bit of AMC harness (thank you Hornet) from the 5th post to the chassis ground. Voila! It now churns over with the remote starter switch!!!

Unfortunately, it still won't churn with the key.

Also, it had no spark from the coil. I don't know if the coil is getting power or if the coil itself is dead. I took the coil out to investigate and I have resistance from terminal to terminal, but nothing from terminal to the plug wire hole (and shouldn't there be some there?)

You really need to get a shop manual for this thing, either a real AMC one or a Motor Manual. I mean really.

That's from a VW website so, you know, grain of salt. But really a true "coil tester" would be smart. Or if it looks old just shotgun the thing and replace with a decent aftermarket part like an MSD Blaster.

I have the factory 1974 AMC Technical Service Manual. The section on the coil says that in order to test it "follow the instructions of the test equipment manufacturer".

Three pages before is the end of the section that walks you through rebuilding the starter end to end and testing all of it. It's odd how some components are so detailed, and others are basically overlooked.

The 73/74 ignition circuit is not very simple either. There's the lock cylinder and rod, GM ignition switch, fuse panel, starter relay, seatbelt lockout sensor, neutral safety switch, starter solenoid, fusible links, starter, distributor and all of it's sensors and electronics, coil, battery, etc, etc.

My 62 Rambler was much simpler.

My buddy in HS had a 73 Javelin/AMX with a 360...it ate starter solnoids like candy. As I recall he would 'jump' the solnoid with a screwdriver to get the car to start. I doubt this is your problem, but I figured I would throw it out there.

Are you using a relay on the ignition switch? If not you probably should, no reason to run the power though the switch if you don't need to.