A few weeks ago my wife was going to drive the truck but when she tried to start it the starter stayed engaged. She turned the keys off and removed the keys and the starter continued to turn.

I finally have all of the broken parts replaced (starter, starter solenoid, added quick disconnect on battery terminal, ring gear...). I tried to start it up last night and had the same issue.

The truck started like normal at first and then I turned it off and removed the keys. The truck continued to run! I disconnected the battery with the newly installed, handy battery quick disconnect. I reconnected everything and tried again but this time the starter stayed engaged until I pulled the plug again.

Has anyone see a similar issue? I am guessing ignition switch as most of the other components are new or recently replaced (battery, starter, starter solenoid, DSII, solenoid, voltage reg, alternator...).

I am hoping to do a frame off in a few years (wife is still finishing school). The most exciting thing to me is going to be a new wiring harness for this truck!

 

Sounds like the starter or ignition circuit is receiving power from somewhere its not supposed to. Have you checked the ignition switch?

 

'had the same issue with my '68 Mustang. It was more from a lack of use and gummy ignition switch contacts. I've been driving it a lot more and the problem has gone away.

 

I have not checked the ignition switch yet. I was out late in the dark trying to get everything else put back together on the transmission side.

I plan on grabbing a new ignition switch this weekend. I was curious if anyone else ever had this problem. It only recently started. the most recent work done was to replace the battery and voltage regulator.

 

I had the same problem with a 92 Mustang, while not a Ford truck the parts involved are the same. When starting the car and with car running the starter was still engaged. Don't want to let it run to long like that.

It turned out to be the fender mounted solenoid. A piece of advise as well, do not get a cheap offshore replacement or you will be doing it again. Ask me how I know?

As much as it pained me, I had to go with cap in hand and get one from a Ford dealer. I little more money, at least double or more, but it has lasted and oh ya it was made in Mexico.

 

My 73 did the same thing a few months back. I had been having trouble getting a new replacement solenoid that was worth installing and after number 3 i thought all was good. The replacements were to get it to start more than a couple of times , so like i said it all looked good . Then that started , so with advice i got , some from here i got a new replacement switch all though i had replaced it about 6 months earlier . Well that never made any difference. Turned out it was another solenoid just doing a different thing than the others. So after one new starter , one new battery, one new alt. four starter solenoids and two ignition switches it may keep going. The hardest and most costly part a keeping them on the road is CHEAP MADE PARTS . I hope you have better luck. JIM

 

You'll probably be replacing the alternator again. It is really tough on them when you disconnect the battery while the engine is running, & the alternator is spinning. You didn't have any other choice though.....

 

I don't know who this is directed at and yes alternators are easy to damage but i shut the engine off by removing the coil wire from the cap with a pair of electrical workers gloves , never got zapped .

 

Well, I thought I finally had it....but no go.

I replaced the ignition switch and the key cylinder as well (it was not looking so good). After I got everything back together I tried hooking up the battery and the starter took off without any keys in the ignition. I pulled the starter relay and checked continuity across the terminal to the battery and terminal to the starter and found continuity. Clearly this would cause the starter to continue to engage.

I put in a new starter relay but didn't connect the battery. I checked for continuity in the same places and found continuity. I checked just the relay from battery side to starter side without wires connected and there was not continuity so the relay is good. I checked continuity/resistance across the black wire on battery side to starter side and found 0.588 Ohms. I checked from the yellow wire (very dirty in picture) on the battery side to the starter side and it had continuity. It appears that there is some short between the starter side and this yellow wire?!

I am out of ideas. I didnt ever hook the battery up since I didnt want to fry anything else. Any ideas or other diagnostics to perform?

 

What's the voltage on the red wire S terminal?

Did the copper lugs turn while tightening? If the lugs turn, the contacts inside might not be aligned right and weld themselves together... You can upgrade to the newer style relay/solenoid like this NAPA Echlin ST404.

If it's not the relay/solenoid, I'm outta idears

 

Oh, that Red/Blue wire going to the starter relay/solenoid 'S' terminal also goes to the Ignition module, Neutral Safety Switch, and then the Ignition switch. The Black Wire on the 'I' terminal goes to the ignition coil + terminal and then goes through a resistor wire (Under Dash) and then the ignition switch. FYI, hope this helps.

 

Did a few more tests..thoughts

There is continuity from yellow wire to black ign wire

There is continuity from yellow wire to starter side of relay.

I started umpluggin things to see if any impact to the short. I unplugget the coil, ignition module, alternator and the short remained.

I think the relay is ok bUT there is a short somewhere on the yellow wire. Any idea where it goes? Ignition switch?

 

I did a 3G upgrade on the wife's truck with a brand new solenoid and it is doing the same damned thing. Key switch is new. Going to go through it with a DMM tomorrow, will see what I find out.

 

Yellow wire is connected to Alt.-Regulator, & Alt. shunt wire.
Shunt wire is the Batt. charge wire coming from Alt. [the big one.]
Which connects to Starter-Sol. Battery (+) side.
-
The small terminal Brown wire goes on (I) Ignition side.
Your small terminal Red w Black-stripe wire goes on the (S) Start side.
_

 

I tried to run down the problem bro, mine just is worse. New starter, solenoid (4th one), 3G alt upgrade, battery, terminal, ECU, ignition switch and coil... As soon you turn the key in the on position, the red wire powers up and engages the starter. Did not do this prior to the 3G, have to pull the red wire off the S terminal to get the starter to stop. It has constant power as soon as the ignition switch hits the on position.