My truck won't turn over with the key. The solenoid clicks, and nothing.

If I jump the solenoid with the key in run, the truck will start and run fine.

If the solenoid clicks, doesn't that mean that it's functioning properly?

If it's functioning properly, then why won't my truck start??

 

Clean all your connection's real good & if that don't do the trick get a new silinoid

 

Does the solenoid click once or numerous times when you hold the key to start?

If it just clicks once and the starter doesn't turn it could be a dead starter solenoid. Check for 12v at the large terminal towards the front of the engine. It should be present there even with the key off. Then turn the key to start and see if the 12v is on the other large terminal , towards the rear. If there is no volts then the solenoid is dead, or you have open or corroded power wires. If you get 12v there then check for 12v at the power terminal of the starter. If there is none there then the power wire is open.

You could also use a jumper cable and bypass the solenoid by putting 12 volts direct to the large terminal to the rear of the solenoid. This should cause your starter to turn if its wiring is good and it has a good ground.

If the solenoid clicks numerous times with the key to run you arent getting 12 volts to the solenoid to close it. Which usually suggests a dead battery, but since yours seems to be good it must be a problem in the wiring from the ignition switch to close the solenoid. Try jumping 12v from the battery direct to the solenoid to see if it closes and the starter turns. If so you have to repair or replace the wire from ignition switch.

 

I cleaned and greased all the contacts on the fenderwall solenoid, and the main ground strap to the engine, and it didn't change anything.

The solenoid only clicks ONCE when I turn the key.

I'll check the rear large post for voltage with the key turned to start.

 

There is voltage on the rear large post of the solenoid when in start, full 12.5 or so.

That's very strange, because my starter seems fine, it starts no trouble when I jump the solenoid, front large post to rear. But the solenoid seems to be communicating voltage fine.

??

 

Could be the ignition switch itself. Can't remember offhand which **** to jump to test, but maybe it went south.

 

It's possible, but if the solenoid is switching on.....?

 

If the solenoid clicks just once (as you said) then nothing, it could be the "spook" voltage at first start trying to jump the open between the start/run internal connections on the switch. Happened to me on my 79.
Stranger things have happened....was ready to blow up my son's 86 150....same thing as your vehicle...did all the voltage, guzinta and other whatnot checks and still the same. Did one last check before pulling out the artillery - pulled the battery connections even though the battery checked out good - there was a thin layer of corrosion encircling the terminals. Nothing on the top, couldn't see any anywhere. Cleaned it - and she fired right up. ARRRRGGGHHH!

 

Lesson learned - eliminate the obvious first......

 

Hot-in-START and hot-in-RUN are separate poles on the ignition switch. It's possible for the hot-in-RUN contact to fail while the hot-in-START circuit remains intact. This would cause the scenario you are seeing.

Turn the key to RUN, and measure the voltage at the positive terminal of the ignition coil. You should see 6 to 7 volts. If you do, then this tells you that the ignition switch is getting power to the coil (because there is voltage present) AND the ignition module (because the power transistor in the ignition module is closing and pulling current through the ballast). Report your results, and we will go from there.

 

Good starter ,strong battery, one click/no start, jump across terminals and starts,= bad solenoid i'm guessing.____My $0.02 worth.

 

Looks like I missed a couple things the first time. When I re-read this thread, I interpret the following:

1) With the key, the solenoid clicks, but the engine does not turn over.

2) When jumping the solenoid, the engine turns over.

This actually points to a bad solenoid as jim describes above. I got side-tracked when the OP wrote "ignition issue" in the title. Not turning over is a starting system problem. The ignition system has nothing to do with it at this point.

My guess is that the solenoid has an internal failure. It's possible that voltage is being applied to the 'S' terminal properly and the slug inside the solenoid is hitting (hence the clicking sound), but the contact plate inside is not moving with it.

You can verify by having a friend turn the key to START (such that the click occurs) and making sure you have the same voltage on all three terminals (two large studs and the 'S' terminal). If you have battery voltage on the large terminal closest to the battery AND the 'S' terminal, but NO voltage on the large stud closest to the starter, then the solenoid must be replaced.

 

I played around with a jumper cable today, and the one time it did anything to change my ability to start my truck, was when I clipped one end to the metal bracket that hangs the solenoid, and one end to the negative battery terminal. Upon turning the key to start, the engine turned over and started right up. Next I put some dielectric grease on the two bolts that hold the solenoid bracket to the inner fender, and now everything works.

I guess the solenoid needs to be grounded?

 

Yup, the solenoid grounds through the mounting bracket. Probably wouldn't hurt to remove the solenoid and sand the splash pan where the bracket mounts and the bracket itself then remount it. Dielectric grease is always a good idea.

 

Ha! I had no idea, this could be the cause of a chronic starting (good point FMC, not strictly ignition) problem I've had since I've owned the truck. I also cleaned and greased all the major connections up front over the course of this investigation, including the two dome light sensors on the doors! That's nice.... I'm going to do all the light sockets soon.