I am having an issue with my 2002 Ford Ranger. It's a club cab XLT 4.0. Has about 225,000 on it. Been doing fine up until the other day. Haven't been driving it much thanks to Brandon and the gas prices so it sits quite a bit. Took an extended trip the other day so it sat for a week without use. When I got home it wouldn't crank, threw it on the charger for a few minutes and got it to start so I could move it around. did alright for a couple of days, nothing noticeable. had to load a downed limb and haul it to the dump. Heading down to the pit to dump the load and just like that, lost power. now I can't get it started back up for nothing. I have battery power, i have replaced the ignition switch, before i replace anything else, we have checked as much as we know that power if flowing, but when I turn the key there is all indication of power but no noise. starter worked, solenoid kicked it over, but it didn't fire which I thought was odd, never really had that problem. I am at a loss for ideas and suggestions. it's like a little gremlin just decided to wave its wand and say, "quit running"!
Any ranger experts out there that can point me in several directions to check what my problem(s) are? need help badly, Thanks! P.S. tried to run a diagnostic or a code reader on it and that was unsuccessful. for some reason it wasn't communicating with the three readers we tried. all I can lend to that is when it shut down, the battery and check gauge light came on and that was it.
previous statement kind of left an open end to the problem. now i can add some stuff in hopes of some suggestions.
we have performed several circuit tests and check in hopes of opening a door. I think we have determined that we have a dead short somewhere. did a test of all the fuses and it shows we have a short but can't determine where?
we keep blowing the PCM fuse. read something that the fuel pump could be the culprit, yet the pump fuse is intact, and the pump is working.

 

continuing saga of my dead truck. as stated previously, driving along and it just up and quit. i have no answers as to why, so i could sure use help.
here's a rundown of what we have done already. maybe that will tweak some ideas. we have determined that the #11(pink PCM fuse) is blowing. can't get past that point.
1 test for a dead short show a dead short but a check of all fuses does not lead us anywhere.
2. to avoid blowing dollars in fuses we are using a 20-amp breaker in place of the #11 fuse. we hook it up to the fuse connection have 12 volts, turn the key on, throws it but we still have 12 volts running thru it. we shouldn't have any.
3. we unhook the breaker to check for continuity, breaker off, have none, breaker on we have continuity. We hook the breaker back up to the
fuse port and we have 12 volts be it on or off. Don't know why we have 12 volts with the breaker off.
4 have 12 volts going thru the pcm, neutral switch, starter, fuel pump, fuel pump is working.
5. all wires to the fuse box are intact and not corroded
6. can't get starter to work thru the ign switch but it will jump to the solenoid.
7. did a dead short test of all fuses but could not find any problems, except with that #11 PCM fuse.
Does anyone have any logical starting points to look for?

 

Welcome to the forum

I missed your first post

There are two fuse 11s
In cab fuse box 7.5amp, feeds dash and some modules, and CEL but not PCM
In engine fuse box 50 amp, feeds ignition switch and starter relay in engine fuse box

2001 to 2003 Rangers have the same power distribution, same fuse/relay layouts, here are the 2001 power diagrams

 

2002 does have PATS(Passive anti-theft system) which disables starter motor but Fuel pump also would not work
And PATS can not kill a running engine, its only enabled to test key when starting engine

Starter circuit does need Fuse 24 in cab fuse box to be good
I would check it if you already found one blown fuse

Fuse 7 in engine bay box(30amp) is the PCM power fuse, and PCM relay in engine bay box passes that power to the PCM
When you turn on the key the CEL(check engine light) on the dash should come on, that means PCM is powered ON
BUT...........fuse 11 in cab powers the CEL(dash lights)

 

I stand corrected. fuse in question is the #7 under the hood. disregard my calling it the #11. wrong! sorry. I'll take what you gave me and see what happens and get back to you. thank you for the help!

 

Fuse 7 feeds a lot of stuff, fuse 7 has 12volt all the time, but fuse 7 only sends out 12v THRU the PCM relay, its controlled by key on/off

Check if fuse 41 in engine bay is OK, pull it and leave it out for now
Fuse 41 gets 12v from fuse 7 when PCM Relay closes(key on)
Fuse 41 powers the O2 heaters, not uncommon for these wires to melt near exhaust pipe and short

PCM relay also power all fuel injectors
Fuel pump relay, not the pump just the pumps on/off relay
And PCM relay powers the PCM


Page 1 has Fuse 7 and PCM relay
Red wire is 12v OUT of relay when key is on

PCM relay is a "mini-relay" slots IDed here: http://www.gtsparkplugs.com/images/m...iring-840x.jpg

Key off
Pull out PCM relay, put fuse 7 in
Test slot 30 and slot 87 with volt meter, only one will show 12volts, that is the 12v from fuse 7
The one without 12v will be the Red wire, remember that slot, mark it if you want(Ford doesn't always follow diagrams, 30 and 87 are interchangeable)

Now test that non-12v slot with OHM Meter to ground(battery negative) should be no lower than say 14 ohms, 0 or close to 0 means a short to ground somewhere
If you see 14 ohm then replace relay it has an internal short
If ohms are close to 0 then follow the RED wire on diagram and unplug devices(like fuse 41) as you go and retest ohms each time
Also move wiring harness's around while OHM Meter is hooked up, could be red wire is shorted to ground wire inside a harness

 

sorry for the delay on reply. thank you so much for the help. we'll check this stuff today and see if we get any results. again, thank you.

 

okay, we have done the ohm test and we had zero. now short of following the red wire, lots of red wires on this thing, we are at a loss. our problem is or so we think, and we are complete amateurs, is we can't do anything until we are able to turn the key on without blowing that #7 fuse. we need to figure out how to get past that, otherwise it's a dead issue. short of being lazy, what else feeds off of that PCM fuse?

 

okay, we have done the ohm test and we had zero. now short of following the red wire, lots of red wires on this thing, we are at a loss. our problem is or so we think, and we are complete amateurs, is we can't do anything until we are able to turn the key on without blowing that #7 fuse. we need to figure out how to get past that, otherwise it's a dead issue. short of being lazy, what else feeds off of that PCM fuse?

 

another question would be, how to check that PCM diode. Should we be getting a 12-volt reading on the hot side of it? upon checking we are only getting a 1 volt reading out of it.

 

Look at the wiring diagram, follow the red wire on the diagram, something on that wire is shorted to ground, i.e. you get 0 ohms
So just use the OHM meter and unplug devices on the red wire until OHM come up from 0

Using OHMs is the SAME as using 12volts but no blown fuses to replace, nothing fancy about OHMs in this application, nothing to learn

The OHM Meter has a battery inside, 2v to 9v depends on the meter
It sends out say 2v on one wire(probe) and gets back 2v on the other wire(probe), that means a direct connection, or 0 ohms
Touch the 2 probes together, 0 ohms, direct connection, you are just applying this to longer and multiple wires

If you were testing a single wire then 0 ohms is good it means wire is not broken
But if you are testing a 12v wire(red wire) to battery negative and see 0 ohms that's bad, it means there is direct connection, a short to Ground

You want OHM meter to send out 2v but only get back 1v, thats good, it means its not 0 ohms, a short
And no blown fuses
With OHM meter you are just using lower voltage and its protected so can tell you if a fuse's wiring out to multiple devices is OK or shorted somewhere


And PCM diode is not on Fuse 7 that's blowing, so can't be part of why fuse 7 is blowing

But yes with key ON slot 86(or 85) in PCM relay slot should show 12v from fuse 19 in the cab
A diode only passes voltage one-way, it usually has an arrow and/or a line
12v in--->|-, 12v out
12v in---|<--0v out

End with line blocks voltage coming in from that end
PCM diode is used because when PCM relay closes there can be a reverse spike voltage, diode prevents any spike from travelling backwards thru the wires to other componets

 

got it. took a bit but we figured out the diagram thing, taped it in unison and highlighted the red wire. now we may figure it out. be back in touch. thanks.

 

by the way, something I keep forgetting to pass on. we have tried analyzing this thing with a code reader. we have tried three different readers yet all we get in return is an error reading or no connection. which puzzles us.

 

With no 12volt on the Red wire(fuse 7) the computer is OFF, so reader can't connect to it

And computer can be the short
You may want to unplug that large 104 wire connector in the upper middle of firewall now, then do OHMs test
If OHMs go up then pull computer out and have a look inside it

 

very good, thank you

 

haven’t tried sending by phone so don’t know if you’ll get it. Following your lead, we go fund the problem in the MAF. Started digging into that and what a miracle. Obvious someone has corrupted previously. All the wires were bare and breaking down. A little clean up and we were off and running. Don’t know how to thank you enough.

 

Good work

Very hard to find these types of problems