1969 Road Runner doesn't crank

Hey guys, I installed new headlights and after installing them, I couldn't get the car to crank with the key in the ignition. The day before installing the new headlights the car started up like normal with no issues, I just rolled the car in and out of the garage to work on it, and haven't been driving it since I had no headlights. The interior lights work as well. I can only get the car to crank if I connect the small and large post of the starter relay. I also tried starting the car in park, drive, neutral, and reverse In the process of this as well I think I damaged something in my charging system, I had the car running since I connected the two posts and then I measured my battery and it had rather low voltage it was floating around 11.9 12.4. Please let me know if anyone can help me out and fix these issues. Thanks.

Gonna need some more info. Are these new headlights and wiring or just replacement factory headlamps? You didn’t leave the 2 posts connected did you after you got it to start? Sounds like you might just have a bad starter relay. There is a small wire on the bottom left of the starter relay that provides ground from the transmission in park and neutral. Is that wire connected?

BLK 68 R/T said:

Gonna need some more info. Are these new headlights and wiring or just replacement factory headlamps? You didn’t leave the 2 posts connected did you after you got it to start? Sounds like you might just have a bad starter relay. There is a small wire on the bottom left of the starter relay that provides ground from the transmission in park and neutral. Is that wire connected?

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The headlights are new. I didnt get any new wiring for them, I took the old ones out since they didn't work at all, and put the new ones in and they worked, but the car doesn't crank with the key now. So I had a screwdriver to connect the two posts, and I took it away when the car started, the car ran fine for a few minutes before I shut it off with the key. And while it was running, I think something in the charging system got damaged because I tested the voltage at the battery and it was rather low I revved it a couple times to see if it would come up some but it did not. I made sure every wire was securely connected.

If you rev the engine up from idle does the battery charge voltage rise or stay the same?

BLK 68 R/T said:

If you rev the engine up from idle does the battery charge voltage rise or stay the same?

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It would rise some, but not a lot whenever I was revving it, it was slowly rasing though I may try letting the car run for longer to see if my charging system took a hit

I would check the bulkhead connections. The extra load of functioning headlights could drag down the system if it was compromised prior to the headlights working. As for the no start, probably just a coincidence. Try a new starter relay and also check the rest of the cable connections for corrosion. If you see green colored copper wires or white, the cables probably need replaced.

BLK 68 R/T said:

I would check the bulkhead connections. The extra load of functioning headlights could drag down the system if it was compromised prior to the headlights working. As for the no start, probably just a coincidence. Try a new starter relay and also check the rest of the cable connections for corrosion. If you see green colored copper wires or white, the cables probably need replaced.

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Yeah, I'll try and see if a new starter relay works, hopefully it does, thanks.

Before you start throwing money at it, get volt meter or a test light and do a couple of easy tests.
1. Make sure you have ground at the brown wire on the starter relay, Park & Neutral.
2. If you can get someone in the car, check for +12V at the yellow wire on the starter relay when the key is in the start position.
If you have those potentials and it still doesn't start, it's the relay.
If you don't have one of either potentials, the problem is elsewhere.

1) I would make sure the neutral safety wire didn't get knocked off the starter relay (brown wire).

2) Run a ground to the terminal the brown wire is connected to just to help insure it is not a neutral safety issue.

3) try a new Starter solenoid.

If you can crank in gear you have some work to do on the neutral safety switch but that should not be cause of the no start.

Like posted grab a volt meter pull the coil wire and start with switch voltage, then starter relay and on down the line, in and out of the ballast resistor .
Coil, you may have shorted out your voltage reg.
Like posted the fire wall bulk head connections need ckd.
I hate electric problems lol, sooner or later you have that ( how did I miss that moment) good luck.

K.I.S.S.

The battery that came with my (just purchased) '70 Charger shows 12v resting, and on the NoCo pulse charger it shows 100% capacity. But the car lived in Florida all its life and is now in the below-freezing weather of Maryland.

Turn the key, CLICK. And that's it.

Swap in a battery from my '91 Daytona, starts right up.

Check standing voltage in your battery. If you have a battery tender (EVERY classic car guy has some sort of battery maintainer, right?), hook it up and wait for the green light. Try again once it says fully charged.

Just because you have volts, doesn't mean you have AMPS, and amps are what start a car. Think of a water hose - you can have "water" trickling out of the hose (volts)...or you can have full-bore, knock-over-a-horse fire-hose water pressure (amps).

Swap batteries with something else in the stable, and see if it starts. If the battery is bad, you will not get a valid test reading - you need to test charging system output levels with a good battery.

I strongly recommend the NoCo line of battery charger/maintainers. I have used BatteryTender units on my motorcycle batteries for years, but they will only float-maintain a good battery. I have had stone-dead batteries brought back to life by NoCo chargers. $40 at WallyWorld. They also make some bad-*** pocket-size jump start power units. The only catch with them is, you may need to hook a jump box to a stone-dead battery long enough for the charger to register "hey, there's a battery here" and start the charging cycle. Usually 2 minutes will do it.

I'm guessing you need an alternator, and a battery. A running 11v is too low, and depending how long it has been run like that you could have damaged a cell in the battery, knocking down its effective amperage. Again, though - put in a known-good battery and re-check voltage at idle, and check for climb with revs.

Relay ground or relay itself.