So, lately I've been having issues (ok, maybe not me, but the Explorer). I'll drive home from work, about a 28 mile drive, mostly interstate. I'll pull in the driveway, shut the truck off, go in the house, and remember that I forgot to make a cigarette stop, damn, go back out again. Hmmm, truck cranks, getting fuel to the places it should be going to, but it won't start! WTF?


Open fuse/relay box under the hood, Ignition relay in the back of the box (closest to firewall, see picture, large light gray square relay in top left corner) is HOT! Not so I hot it's melting, but I'm thinking that isn't a good thing (not me thinking, but a hot relay, at least it isn't in the relays on the stuff I work on during the day while someone pays me).


Wait about 20-30 minutes, go back out, it starts right up, no problems!


So, I'm going to do the one thing I've taught my daughter not to do and that's assume. I'm assuming (the horror of it all!) that this "not starting" thing could be related to a freaking hot ignition relay. Sure, it could be the fuel pump, or any number of other items on the "list", but I'm looking at the easiest to fix stuff first, plus, dropping the fuel tank isn't high on my list right now.


I guess my first question is, that relay shouldn't be that hot, should it? And heck it's cheap enough to replace without removing most of the money in my bank account.


Thanks in advance for any help, insight, correct lottery numbers, jokes, riddles, single women's phone numbers, etc. that anyone can provide!

 

The next time it wont start turn the key one click. The check engine light should come on & you should hear the fuel pump run for 2 seconds. If not, it's not going to start.
What are you driving?

 

I'll have to get someone that can actually hear something to do the listening, my hearing is shot. Problem is, it never happens when someone else is around, go figure.

02 Ex, XLT, V6, not flex. 2WD, 143K miles

 

no engine codes, temp sensor error, etc ?

 

There's a bunch of stuff that receives power via that relay, but if the relay itself is getting hot, that suggests that there is resistance in the contacts that is causing power to be dissipated as heat when the ignition is on. Seems like changing it out would be a wise choice.

Finding that hot relay was pretty observant on your part!

-Rod

 

No codes, no nothing.

 

I figured as much. A relay can/will get warm, but not that warm!

 

The relay getting hot is a symptom, not a cause though?

 

That would be my thinking. Nothing like opening a can of worms is there?

 

Well like the man said though, you caught it. Observation is a good thing. What's causing all the juice to flow?

Have you recently "detailed" the engine bay with a pressure washer? Just thinking out loud lol

 

Good question. More research to follow


Nope, no pressure washing of the engine bay, and we haven't had much rain, so I can't attribute it to that.

 

There are a whole lot of circuits that, by design, will cause current to flow through that relay when the ignition is on. If I interpreted the original post correctly, the relay was hot after driving, but after the relay (and vehicle) had a chance to cool off, the vehicle started and presumably the relay was not still hot. If that's accurate, then it would not be surprising that quite a lot of current would be flowing through that relay during normal driving. But getting hot due to that current flowing would suggest the contacts within the relay are providing a resistance to the current flow which is dissipated as heat. So the heat would be the symptom caused by worn/dirty contacts within the relay.

Whether that worn relay is the cause for the no start condition (whose symptoms also match that of a failing fuel pump or fuel pump relay) is yet to be determined.

-Rod

 

I've been looking for a wiring diagram, but haven't had any luck yet. I'm too stubborn to give in to taking it to the dealership, but if they can diagnose the problem for a few bucks, I can make the fix.

 

Maybe this will help...
(Tried to be as accurate as possible however, this may not be your exact vehicle)

 

Many thanks! I'll give these the once over when I get home this afternoon.