So I swapped out my factory steering wheel for a prettier Grant walnut one. During the swap I ended up pulling the 30 amp fuse for the horn, and accidently pulled the 15 amp fuse next to it, (i put this right back in, and am not sure what it is for as I left the truck at home today) This morning I went out and started the truck to "preheat" the cab about 20 minutes before I left. When I took off I noticed the oil pressure was all the way on 'H', the tach wasn't responding, and I had no reading on the voltmeter. In addition the engine kept jumping from about 1000-1500 rpms (not really sure, just going by ear) when I was driving down the road. Needless to say, after about 4 blocks I turned around and parked it.

I have a 4.9

What did I do, and how can I fix it?

 

first I would try a reset. Ford's reset i believe is turning everything in the cab off (climate controls off, fan on lo, lights off, etc.) and turn the key from off to on 5 or 10 times. Every manufacturer has a reset you can do. This one im not fully sure on, this one might be chevy or pontiac. But it might do something. What fuse was it? you said 15 amp, do you still have your panel that gives you a map out of the fuses?

 

So i neglected to tell you all that i did all of this in the dark, with only the cab lights to see by. I put the 15 amp fuse (18 on the diagram) where a 10 amp fuse (15 on the diagram) was supposed to go. Can't believe I missed this...

 

Ain't ever heard of this on a Ford. Older Chrysler junk you can do this to pull codes (equivalent to jumpering the STO wire on OBD1 Fords).

I'd say perhaps you put the fuse in the wrong place. Using a 15A fuse in place of a 10A won't cause this to happen unless the 15A fuse was already blown.

Make sure to put the 15A one back where it belongs, and more importantly don't use it on a circuit that's only designed for 10A.

 

Double check you have fuses in the correct spots. Pull your negative battery cable and let the truck sit for 10 minutes. It'll reset the ECU. Then start the truck up, let it warm up, drive around for 10-15 minutes and the computer will "re-learn" your truck.

 

I went out after work yesterday (when it was daylight) and found the fuse in the wrong place, put it back where it belonged and everything worked the way it was supposed to.

Thanks for the help guys.