84 f150 start circut problem

new starter,relay,ignition switch,key switch,batt cables even to the starter i hook up the battery and it still engages the starter on it's own.i'm lost,i checked eveything HELP!!!!

Reply to
jimmithewrench
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Pull the small wire off the starter relay ("S" terminal, if so marked) and see what happens.

That wire should only be hot with the ignition switch in the "start" position...

Reply to
Rick

thanks rick,just checked that,works only in start possition,i went one step further disconected the relay starter side and turned the key on,jumped from the bat right to the wire to the starter and it starts and runs,tryed a 3 relay and does the same thing...lost

Reply to
jimmithewrench

on,jumped

runs,tryed

I'm kind of lost by your description. The cable from the starter motor should be on one side of the starter relay, all by itself. The battery cable and any additional ones from alternator, etc. should be on the other side. Are you saying the engine cranks as soon as the battery cable is connected to the battery, even if the small wire is off the starter relay?

I'd expect it to be similar to this....

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Reply to
Rick

yes it ju7st cranks as it did when i bought it for a plow truck,i even took the wire to the the relay and put it on a toggle switch....from the ign,. switch,and it keeps trying to start.i even took the other 2 cables off the battery side of the solinoid,,,,it still want's to start,,,,can it be a ground feeding back?? some where??/ i did the test with the- disconected w/the test light and nothithing lit

Reply to
jimmithewrench

look.... the other wires on the battery side of the solenoid have nothing to do with it..they supply power to other circuits.

  • >>>>> Term relay Term >>>> Starter are the big wires, leave them alone, only 1 big wire on starter side, may be several wires hooked to batt side

the two small terminals on that relay 1 is to energize the relay, the other to supply full power to the coil.

If you reverse them, the solenoid may energize whenever the key is on.

So disconnect them both, if starter still wants to crank, you have a bad solenoid. If the starter doesnt crank, install one of the wires on left small term. if it cranks when key switched on, remove it and install other wire on same terminal. it should then only crank with key in start position. If so, install other wire on other terminal.

If it doesnt seem to matter, and either wire causes the problem then you have a bad ign switch.

Reply to
Backyard Mechanic

disconected

Very odd-any chance it had a dual battery setup that was partially removed?.

Reply to
Rick

switch....from

other 2

install

Pretty much been through all that already. He said he replaced the ignition switch, tried 3 solenoids, and it tries to crank as soon as the battery is connected, even with the small wire(s) disconnected.

To be honest, from his descriptions I can't tell what he's doing with the cables, if it did this when he bought it or after he added the plow, etc...

Reply to
Rick

Well that's the point... if he has already replaced the ign switch AND the solenoid relay, AND it still cranks when connected with both small terminals disconnected then the thing has to be 'possessed'

And it IS NOT clear that he tried with both small terminals empty.

The key is in that relay/solenoid. If it isnt fried - meaning contacts are welded together.. and it only clicks when key is on, then something is wired wrong.

Just to be absolutely clear on this...one of those small terminals is connected to coil of the relay and positive voltage energizes the relay, the other is a contact output and provides positive power when relay is engaged; this is used to switch 12v directly to the coil while cranking...

thus when the key is ON, its connecting wire will have the same positive voltage as the + terminal of the coil but current (thus voltage seen on it) is reduced by the coil ballast resistor. In many cases, this will still be enough power to energize the relay

Reply to
Backyard Mechanic

A HUGE thankyou to both rick and the "krusty old geezer',yes i did buy the truck w/the supossed problem of starters burnin up. i checked the flywheel and was ok so i bought it.I did test the single wire from the ignition switch[kusty] only 1 wire on this set up,yes it was hot constant,i put in a new ignition switch.it tested fine at 1rst.i thought i put the old[2nd] solinoid through enough so put on #3 i know the other wires are running other things but have had them short before and weld the solinoid contacts,it's been years since i've delt with theese and you both wolk me up..it turns out the idiot who sold me this took scotch locks ewwwwwww and used the wires under the dash that he could find to wire in a stereo & amp.yes the truck did seem to be possesed thank you both of you jimmithewrench GOD SUPERSTOCKS ARE SO MUCH EASIER!

Reply to
jimmithewrench

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