My truck will randomly be difficult to start. When I turn the key sometimes it sounds like a dead battery almost but eventually it catches and fires right up. It just does it at random times. Well, this morning I swung by my wifes work to drop off a package and it did it again. I noticed some smoke coming from under the hood, (toward the front corner, passengers side), I opened the hood and this guy was smoking a little bit. I got back in and the truck started with no problem at all.
What part is this and what's it do?

EDIT: Just to clarify, I'm talking about the brown thing with the wires connected to it. It's on the passenger side toward the front. You can see the battery in the lower left of the pic.

 

That's the starter solenoid. It acts like the switch to run the starter when you turn the key. If it was smoking, you have connection issues. It appears to have some corrosion on the terminals. All you have to do is remove the cables, clean the cable ends and the posts and put it back together. I wouldn't put this off long either. These can start a fire if they get hot enough. It's probably a good idea to clean the terminal at the starter as well. Make sure to disconnect the battery when doing any of this.

 

Thanks Labnerd!
The truck did start up fine after popping the hood so maybe it does just need to be cleaned. I don't mind replacing it if need be but I'll clean it first. No use spending money if I don't need to.

Thanks again!

 

If those terminals got hot enough to smoke I would replace it. I would buy genuine Ford as there is some low quality stuff out there.

 

You think MotoCraft parts would be ok? Amazon has them for about $25.

 

Motorcraft is ideally what you want. I'd just stay away from generic and house brand parts at parts stores. I probably would trust one from NAPA if it's an Echlin.

Parts catalogs list it as a starter relay, not a solenoid.

 

U see that brown nut and cable attached to it. They are damaged due to heat/bad connection. Replace them with new and probably the relay also.

 

I can see the corrosion on all of those connections. Pull your negative battery cable first, then use a wire brush to clean each ring terminal individually. I'd use a Ford junkyard relay before I bought a China knock off.

Adrianspeeder

 

Ok, I replaced the solenoid a few minutes ago. Now the truck wont start. It turns over like its going to start but then immediately dies. The interior light doesnt come on like it normally does when I open the door but all the gauges power up when I put the key in and turn it. Also, the battery light is on now.
I reconnected everything just like it was when I took it off.

 

U have a bad terminal on the wire. Replace it at good shiny copper. Worse case, the wire has just got too hot and needs replaced also. Extreme heat and copper are a bad. Where the brown happens it has smoked with heat/resistance/corrosion and the copper is damaged. The brown area has glowed red in the past then changed to brown after coold down. I can't stress enough. Do not continue to use these brown areas, U will burn up a lot of stuff. U need complete clean shiny copper to guarantee success. Out in the back county to get home a clean up might be enough, but not to continue that way. Go new on the battery cables and relay and make sure the small feeds are very good also. It is best now.

U have pulled a lot of current, U may need a battery down the road shortly. Resistance like this is not good, but U have been fairly lucky so far.

 

Update: Replaced the solenoid, replaced both battery cables with brand new ones.
Still wont start. It was trying to crank earlier but now it just makes a clicking sound when I turn it over. Had a neighbor underneath tapping on the starter but that didn't do anything different. I had the battery checked at Autozone and it tested OK.
Now the headlights or interior lights wont come on but the gauges do move when I turn the key.

 

check your engine wire,had same issues on my 96.relocated wire and runs like a champ now

 

Engine wire?????

 

Maybe he means engine block ground wire?

 

yes that wire it was a corroded conection