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jpearson311 09-04-2013 09:50 PM

My truck started without a key
Hi all. So the craziest thing happened to me today. I went out to start my truck (1977 Ford F100 2WD 5.0 302 V8) and it was just clicking, it wouldn't start. Mind you that it was doing this the other day so I replaced the starter and the starter solenoid. I started it a number of times since I replaced them and it fired right up, and idled just fine. Well, it wouldn't start today so I turned the key off, took it out, and popped the hood. When I popped the hood, the negative terminal of the battery started smoking and I noticed some smoke on the opposite side of the engine bay, but down low. Like on the driver's side of the flywheel. It eventually stopped smoking and then all of a sudden it started turning over, by itself. It was in gear so it damn near crushed me against my garage wall. So I assumed that the battery was fried so I took it out and went to auto zone to buy a new one. I put the new battery in, cleaned up the wire ends really well, and coated the battery terminals with dialectic grease. I reconnected the positive battery cable and when I reconnected, or touched rather, the negative cable to the negative terminal, it started sparking again and the starter began to engage/spin. I decided to just leave it alone for the rest of the evening, but I was thinking that the solenoid could be stuck on the inside. Meaning that even if the key/ignition isn't turned on, the starter would still want to engage. The only problem is that the solenoid is brand new. Or, something is faulty in the ignition. What do you guys think? I really need to get this fixed. Thanks!


Windows on Wash 09-05-2013 06:07 AM

If the key was out and it started, the ignition interlock and switch is done.

Be careful and post up and update. Get a voltmeter/test light and start from the bottom up.

rusty baker 09-05-2013 07:41 AM

could be a short.

jpearson311 09-05-2013 09:11 AM


Originally Posted by Windows on Wash (Post 1238314)
If the key was out and it started, the ignition interlock and switch is done.

Be careful and post up and update. Get a voltmeter/test light and start from the bottom up.

What is the ignition interlock and what do you mean start from the bottom up? Thanks!


danpik 09-05-2013 10:48 AM

Sounds like a bad/stuck solenoid. The ignition interlock only allows the power to get to the solenoid via the ignition switch. The solenoid is simply a switch in the positive cable from the battery to the starter. To verify this, unhook the small "hot" wire from the solenoid and hook the battery back up. This is the wire that energizes the solenoid to complete/close the circuit. If it still turns over then the solenoid is stuck in the closed position. Pretty unusuall, but I have seen it happen. If it does not turn over, then the problem lies in the ignition switch circuit.

47_47 09-05-2013 12:08 PM

Try to safely do as much troubleshooting while the problem is active.

With both ends of the battery disconnected, check for continuity across the solenoid. You can use a dvom and measure resistance. If the resistance is zero (continuity), the solenoid is stuck.

Let us know the results of this test and how many small leads the solenoid has connected.

joed 09-05-2013 12:25 PM

The solenoid coil wire could be shorted activating the solenoid.

Willie T 09-05-2013 02:28 PM

Dunno what it is, but I want to be your auto parts guy. I might sell you a whole engine next. :whistling2:

Maintenance 6 09-12-2013 01:22 PM

If you saw smoke on the drivers side, low, at the rear of the engine, then I would check the ignition switch. The actual electrical ignition switch is close to the floor, mounted on top of the steering column tube. A rod runs up to the key switch. There may be a short in the wiring near near that switch. I am assuming that the truck is stick shift, but if it's automatic, then the neutral safety switch at the base of the steering column too. You could have a short there. Unplug them and inspect the connectors. Look for any burned tape or wrapping.

beenthere 09-12-2013 05:38 PM

I don't like this kind of thread. The Op has a dangerous situation going on. And with no update, we don't know if he got seriously injured. Or managed to fix it, and all is ok.

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