starter stays on

[davalex]

have a 93 f150 5.0 liter. I started the truck ,drove it all fine.but when I parked and turned off key the starter was going ,had to disconnect battery to make it stop.now when I start the truck almost always the starter keeps going even when I turn key off.I replaced the ignition module, still does it. had the starter tested and they said it was good.(starter has less than 1000 miles on it.) any ideas?? thanks....dave

[big white bufflo]

starter relay on the fender well it a easy fix and cost less than 30$ next time it happens open the hood and tap in the relay see if it lets go because if it arcs in ternaly it could stick

[Selectron]

I agree that it's most likely the starter relay. A starter relay is usually small and cylindrical, with a couple of mounting lugs for bolting it to the fender or firewall, and I think yours should have three terminals (some have four). If you look at your starter motor, it will have a heavy duty red wire which comes from the battery - ignore that one and follow the other, thinner red wire, and that will lead you back to the starter relay.

The wiring diagram for your starter circuit is at the top left of this page, and if that link doesn't work then try this one instead.

[FNA]

"I replaced the ignition module" Okay.

When you have a problem with your starter, you can be pretty sure that the problem is in the starting system. As suggested, the relay is a good place to look. Your key switch also is a control for operation of the starter. 17 years is good life for a key switch this era.

Since the starter was recently installed, it is a good idea to check the wiring too.

[davalex]

replaced starter relay,problem is still there.could it still be the starter even though it tested good??

[Selectron]

If a replacement solenoid hasn't fixed it then it's one of three things:

1. Faulty starter motor assembly
2. The red/light blue wire which connects to the starter relay is receiving 12 volts when it shouldn't be
3. The red wire from starter relay to starter motor assembly is receiving 12 volts when it shouldn't be.

You won't know which one of those it is unless you do some voltage checks using either a multimeter (DC voltage range) or a 12 volt test lamp. You won't want the starter motor to be cranking while you're checking voltages, so you'll need to disconnect the red wire which runs from the starter relay to the starter solenoid (the starter solenoid is physically attached to the starter motor body) - disconnect whichever end of the wire is easiest to access.

Put the gearshift in Neutral if it's a manual, or in Park or Neutral if it's an automatic, then switch the ignition to the Run position - that's the position where the gauges come to life and the dashboard warning lamps illuminate.

Then check the voltage at the red/light blue wire on the starter relay - it should be at 0 volts, so if you find 12 volts then that's the problem, and it will likely be a short-circuit somewhere along that wire.

If you have 0 volts on that wire then check the voltage at the terminal for the red wire on the starter relay - that's the red wire which runs from the relay to the starter solenoid. That should also be at 0 volts, and if you find 12 volts instead then that's a fault, and what happens next depends on which end of the wire you disconnected. If you disconnected it at the relay then that would indicate a faulty relay, but that's unlikely since it's a new one. If you disconnected it at the starter solenoid, then disconnect it at the relay end also and check the voltage again - if the relay terminal has now dropped from 12 volts to 0 volts but the disconnected wire still has 12 volts then there's a short-circuit somewhere along that length of wire.

Finally, if the relay checks out ok and you have 0 volts on the red/light blue wire and 0 volts on the red wire which runs from starter relay to starter solenoid, then that would be pointing towards a faulty starter motor assembly.

Let me know if you don't follow any of that.

By the way, I don't think it will be the ignition switch because even if the switch's Start contacts were faulty and sending a constant 12 volts to the starter relay coil, the Park/Neutral Position Switch would interrupt the circuit on an automatic and prevent it from cranking, or the Clutch Pedal Position switch would do the same on a manual. Therefore I reckon it's not the switch.

[Selectron]

Actually, there's a real easy way to determine if the fault is in the starter motor assembly or not. Go to the starter motor and you will see three terminals - two have heavy gauge cables attached, and the third is a smaller terminal with a much thinner wire - disconnect that wire (it's the one which comes from the starter relay). Then get a length of wire, strip some insulation from the end and connect it to that same terminal. Then route the other end of the wire up to near the battery - strip a quarter inch of insulation from the end but don't actually connect it to anything - just have it sitting there ready.

Then ensure that the truck is in Neutral if it's a manual, or Neutral or Park if it's an automatic, and apply the parking brake firmly. Switch the ignition to the Run position and then go around to the engine bay and touch the bare end of that wire against the battery positive terminal - the engine will crank and fire - take the wire away from the battery as soon as it's running. Then go and turn your ignition switch off - if it continues to crank then it must be a fault in the starter motor solenoid, but if it now behaves normally then you know that the starter motor is good and therefore the fault must be in the relay or its associated wiring (do it a few times to ensure that it really is working normally).

If you're not used to doing electrical fault-finding then I'd recommend doing that before any electrical checks, and it will quickly tell you where the problem is.

[serge_saati]

I agree with Selectron's post.
If we refer on the schema, postitive goes directly on solenoid switch and solenoid's relay switch. We know that the solenoid's relay is replaced. But maybe the solenoid switch is sticking. Or there's a short circuit in the starter relay input terminal.

I know my post is confusing with solenoid and solenoid relay (2 different parts).
To narrow the problem, do these test while key is off:

-Remove starter relay (not solenoid) and check conductivity in switch female input pin.
-Then check voltage on coil input pin (still in fuse panel).
If you didn't find any problems there, the problem is the starter solenoid.

Or a simpler way:
when your turn to off and it still running, just remove the starter relay. If it doesn't stop, it's the solenoid.

[davalex]

problem fixed !! I followed selectrons advice and it was the solenoid. it now starts and stops as it should. thank all of you for your input,it is greately appreciated. Dave