My truck died on the road nd after having it towed home and findihg no fuel pressure was looking at the fuel pump. In tracin the circuit I discovered the PCM relay powers the fule pump relay. Further investigation found F24 for the PCM was blown. Put in another 30 amp and tried to start truck, the new fuse blew and it never started. It appears there are a number of things powered from this fuse. Any clues on where I should start looking for the mostly likely cause? For information I had a aftermarket remote start with keyless entry installed about aboiut 6 years ago. Other than that no electrical work has been done.

Any help is greatly appreciated.

 

A little more info. I found if I pull the 5 amp fuse number 20 in the junction fuse panel (PCM/GEM module fuse) then I no longer blow the #24 fuse andf the truck will run. ANy Ideas?

 

Check your O2 sensor harnesses to see if one of them is making contact with either an exhaust or moving drivetrain component.

I'd suspect the F20 circumstance is probably a coincidence based on a quick scan of the schematics.


Steve

 

Your are right about the F20 being a coincidence. I have looked at the O2 harnesses and did not see any areas that may be of concern. Guess I will keep looking and thanks for the input.

 

If anyone else has any suggestions I really could use them. This fuse is a 30amp maxi fuse in the power distribution box in the engine compartment. The problem has been intermittent and seems to correct itself and reoccur. The only circuit I can rule out is the fuel pump relay was removed and it was still blowingthe fuse with this out. Currently the truck runs and no fuse problems. I have looked the wiring harness over carefully and can find no areas or damage where a wire may be shorting. Can anyone think of a component that could cause the fuse to blow and be intermittent. When the truck runs it rusn with no problems and no MIL has been set.

 

PDB Fuse F24 operates (via the energized PCM Power Relay), most of the actuators and loads under the hood:

The list is:

MAF Sensor
PCM
Vapor Management valve
Canister Purge solenoid
Auto Transmission solenoids (if auto)
Heaters for all four O2 sensors
Coil of fuel pump relay
Injectors
IAC Valve
EVR solenoid
IMRC (if present, engine dependent)

As you can see, this power distribution line goes to many places. Most commonly, the O2 sensor harnesses have been the problem. I've also see an single report of a chafed harness around the rear of the engine (the poster was not more specific).

Since your symptom is intermittent, you will need to see if you can find a circumstance that causes the problem so it can be duplicated during diagnostics. Barring that, you don't have any simple way to find the fault.

Don't envy your position. This is likely to be a repair that will take even an experienced technician considerable time to isolate since it is intermittent and is on a widespread circuit.

Steve

Edit: If you want to read previous histories pertaining to this fault on this forum, the BEST way is to use Google's site search feature (the site's own SEARCH feature likes longer search strings than "F24").

Google "fuse F24 site:www.f150online.com" without the quotes. There are several very good threads, some with resolutions that may be of help.

Steve

 

Hi! new to this post & looks inviting. I'll bet you if you pull the pcm & remove the cover you will probably find some corrosion in there. Had one time at my dealer that was doing this. Spent alot of time trying to pinpoint the problem. Since you have all those eronious codes, it will throw you for a loop.

 

My brother is haveing the same issue fuse 24 blowing. Can not find any bare wires any where. Anyone no where I can grab a pic of the PCM location so I can send it to him.
98 f-150 4.2 standard cab 4x4

 

My brother found his, it was 02 sensor wire as well. He said there was a tube coming from the engine that was rubbing the 02 sensor wire he is supposed to take some pics and give to me so I can upload them here.
1998 f150 standard cab 4 speed with OD manual trans 4x4 4.2 litre 122,000 miles.

 

you have a short somewhere on that list. the best way to find it would be to look at the harness where it plugs into those specific things and go from there. Also you might be able to blow the fuse and then hook it a code reader and get an idea of where to start.

 

Ummm... He already found the problem....

See my previous post.

A code reader will be completely worthless in this failure since, with a blown fuse, the PCM will have no power leving the code reader with nothing to talk to.

Steve

 

1998 F150, V6 - Truck died while driving and wouldn't restart. Found that F24 fuse had blown. Replaced it, blew immediately. Found this thread and started looking around. A bundle of wires by the firewall was too close to the exhaust manifold and melted 5 wires together. We separated the wires, taped them, moved the bundle of wires away, replaced the fuse and it started right up. I wouldn't have figured it out so quickly without this thread. THANKS!!!