These other fellows are leading you on the right track. You just keep disconnecting electrical components until the fuse stops blowing and then you know which one is drawing too much current.

 

Yess!! My truck runs now!!

I need to offer many thanks to Temp1, JMC, ProjectSHO89, for their expert advice on pinpointing my problem. The problem was the radio noise capacitors, and when my brother-in-law unplugged both of them and I replaced the fuse, the truck fired right up! Should I replace those capacitors?

Also, good luck to TruBluGT, I hope you get your problem resolved.

Kevin

 

Where are the Radio Noise Capacitors so I can try it on mine???

 

anyone??

 

01TruBluGT,

If you are blowing fuse #24 30A in the Power Distribution Box in the cab, finding the Caps will not cure the problem. They are on a different circuit. The MAF sensor, Vapor management valve, Canestor vent solenoid, all 8 fuel injectors, Idle Air Control valve, EGR Vacuum Regulator Solenoid, Intake manifold Tuning Valve, Both Front and rear O2 Sensor heaters, the Tranny and finally the Fuel Pump Relay are all provided +12V from this Fuse when the PCM power relay is powered from the #30 Fuse in the in Battery Junction Box . This same #24 fuse provides a contuinous 12v to the PCM. At least all these wires are red except for the one that is continous to the PCM it should be yellow with a black stripe to the 5 amp fuse in the engine fuse module from there it changes color to Black with light green stripe.

First before you go pulling out all your hair a few questions. Did you have the tannny serviced before this started happening? Do you have any mods done to the truck? Headers, FIPK or other cold air intake? Any repairs done? O2 Sensors replaced?

JMC

 

Be patient. While your truck is urgent to you, the rest of us have our own problems....uh, well, stuff....

Yes, your DMM should work. Select the lowest OHMs scale.

Connect one lead to ground. Key OFF. Pull F24.

Connect other DMM lead to RED wire at the MAF (it's easy to get to, so use it for now).

You will likely read almost 0 ohms to ground. That is your short circuit that must be removed.

JMC's list looks prety good. Start with it since I'm sure you already followed my previous instructions on looking at the O2 sensor wires and any harness near anything moving. Start unplugging each item and watching the meter.

If you disconnect a component that has the short, the reading will jump up, probably to several ohms or more.

Good luck. Short circuits are extremely difficult to locate unless you practice patience and thoroughness.

Steve

 

Project - Thanks I will try it with the DMM and see what happens. One question. If the ohms read 0 on the MAF does that mean that the short is in that wire or just somewhere in the system?

I guess what I am getting at is if I get the wiring diagram for the truck and start at the harness closest to the fuse location and that one reads some ohms, then to the next connection and it reads some ohms, then when I get to the next one it reads 0 should the short be somewhere between the last good reading and the 0 reading?

JMC - To answer your questions... No tranny service since I had a new clutch put in over a year ago. No mods whatsoever she is stock as they come. The only repairs in the last few weeks was a new front bumper that I put on as I got in a bit of a fender bender. O2 sensors are stock as far as I know.

 

If you have any any aftermarket electrical components installed, remove them. I had a bad ground on a siren, and it shorted the whole computer system out, and made everything go crazy. I couldn't figure out what was going on, untill I disconnected the siren. I fixed the ground and it has worked for years.

 

Those capacitors are there to eliminate static on the AM band of the radio. Other folks could hear the noise on their AM bands if there close to your truck. I don't know if there are any laws against radio noise. You should be able to hear the static it if you tune your AM radio just right and rev the engine. The static should increase/decrease with engine RPM's.

Your call.

 

Hi folks,

Just thought i'd throw my 2 cents worth in. I am having the same problem with my 02 SCrew, although mine is intermittent, which means if it ain't broke you can't find the problem, hopefully I find some Ideas when you guys fix yours.
Given the electrical engineering degree that I paid tons of money for, I thought I'd try to provide a little information on reading ohms and what the readings mean.

Ohms is measure of resistance in an electrical circuit, if the DMM is showing zero or very near zero, this means that two wires are touching somewhere in the circuit, IE a short. If the resistance is greater than zero then the circuit is open, ie no short.

This can get a little tricky if there are devices in the circuit that have a low natural resistance, solenoids, etc,as they may be shorted and not show much change in resistance. The first rule of troubleshooting an electrical circuit is to start at one end and work to the other end eliminating devices and branch circuits as you go

So to answer 01TruBluGT, yes start with the first connector closest to the fuse box and disconnect the harness. The DMM should go to infinite resistance. Being a digital meter, it will probably display "OL", at least thats what most DMM's (digital multimeter's) display. If it is an analog meter, ie one with a needle, the needle should move as far away form zero as is possible. This means that the harness between the fuse block and where you disconnected it is good, no shorts. Continue this process by moving to the next available place to unhook the harness from the rest of the harness or device, each time you unhook something the meter should show no short, until you go past the part that has the short. In other words, unhook harness at point "D" and no short, put it back together and unhook at point "E", you still show a short. This means that the short is between points "D" and "E".

Hope this helps out with using meter and good luck.

 

Hey man my fuse box looks just like this, do you know which ones are the parking lights and the one that is the day time running lights as I think I may have blown a fuse wiring up halos improperly.

 

Your owner's manual has fuse charts. If you don't have one you can download a PDF:

http://www.fleet.ford.com/partsandse...owner-manuals/

 

can you tell methere those noise things are located.. I am having exact same problem

 

Mine did the same thing and tried everything. But I took off the gem module and put it back on and it fired right up and haven't had any issues since. I think it was just loose.

 

I'm here with a similar problem.. I suspect i'll find a grounded wire near the exhaust.. if not then behind the throttebody.

I read where the guy put a 100 amp fuse in place of the 30.. I just wanted to educate others reading this who might be in the same situation..

You do NOT want to put the higher fuse in on a bad circuit. That is a bad thing to do, it's dumb. If anything, pull another fuse from a non essential to start up circuit.
Maybe a windshield wiper motor circuit or something like that. The last thing you want to do is create more problems making it harder to fix because now you have 2 problems compounded. If you blow the pcm, then replace it, you might blow it agian because you didn't fix the original problem... but you put in a fuse to make it worse.

If after i look for wires near the headers & cat and dont find any burned wires, i will pull the battery out and start tracing the wires from the PCM.

hopefully I find it. also double check the grounds on the firewall