Radio, windows, starter without ignition switch
#1
09-04-2011, 04:23 PM
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Radio, windows, starter without ignition switch
This morning my son got into his 1999 F150 and the radio was on, before he'd even put the key into the ignition. The power windows were working as well. We pulled the truck into the garage, and after a few minutes the truck tried to start itself, again without the key. We had to disconnect the battery to get it to stop.
The problem happens even if we disconnect the ignition switch. Any ideas on what else could cause this problem?
The problem happens even if we disconnect the ignition switch. Any ideas on what else could cause this problem?
#3
09-04-2011, 09:02 PM
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Car starting by itself. This is my best guess.
The starting circuit has 2 parallel lines.
Always Hot -- Starter Relay (normally open) -- Starter -- Ground (load line)
Hot in Start -- TRS ------- Starter Relay -- PCM -- Ground (control line)
The control line energizes the relay coil, and completes the load line. If the relay is faulty (stuck closed) or the wire to the relay control (bold line) is shorted to +12V, theoretically the starter can start without ignition switch or TRS. How often does it happen?
I don't know about F150. But on my Ford Taurus, radio gets power from the starter control line. Just FYI only.
The starting circuit has 2 parallel lines.
Always Hot -- Starter Relay (normally open) -- Starter -- Ground (load line)
Hot in Start -- TRS ------- Starter Relay -- PCM -- Ground (control line)
The control line energizes the relay coil, and completes the load line. If the relay is faulty (stuck closed) or the wire to the relay control (bold line) is shorted to +12V, theoretically the starter can start without ignition switch or TRS. How often does it happen?
I don't know about F150. But on my Ford Taurus, radio gets power from the starter control line. Just FYI only.
Last edited by paker; 09-04-2011 at 09:13 PM.
#4
09-05-2011, 10:51 AM
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Toyz: No remote start on this truck, unfortunately.
Paker: Yesterday it was happening every few seconds.
It had rained hard the night before so we ran some fans on it last night, in case of a moisture problem. Then today it was behaving fine, until we went ahead and started it up; after about 20 seconds of running the starter started to engage again.
Thanks for the note about the starter control line.. I'm taking another look at the schematic to see if I can figure that out.
Paker: Yesterday it was happening every few seconds.
It had rained hard the night before so we ran some fans on it last night, in case of a moisture problem. Then today it was behaving fine, until we went ahead and started it up; after about 20 seconds of running the starter started to engage again.
Thanks for the note about the starter control line.. I'm taking another look at the schematic to see if I can figure that out.
Last edited by kskuhlman; 09-05-2011 at 10:55 AM.
#6
09-15-2011, 02:27 PM
hey, i have this same problem. except for the truck starting itself.
i have been hit with alot of rain these last couple of days, i just wantd to know if you figured out what your problem was.
please help this is my only truck and i need it everyday, i would like to fix it myself, if possible, instead of paying big bucks.
thanks for anyhelp
i have been hit with alot of rain these last couple of days, i just wantd to know if you figured out what your problem was.
please help this is my only truck and i need it everyday, i would like to fix it myself, if possible, instead of paying big bucks.
thanks for anyhelp
