1993 4.9 F50, auto trans. The truck suddenly shut down while driving down the road. Pulled to the side and tried to restart....nothing! checked around, found no spark, and no fuel. Checked fuses, and found the #9 underhood 20 amp maxi fuse was blown. Replaced the fuse drove a short distance and then the above happened again! It is my understanding that this fuse is for the PCM? and has some direct relations, to the relay nearest the driver fender in the under hood fuse panel...correct? This is the PCM relay right? So what would you guys think I should be checking? Anyone have a good wiring diagram? Or know the circuit protected by this fuse? Thanks in advance to any help...I sure need it!

 

Okay it seems this thing will idle all day long, but you can only drive a short distance and then it will shut down and the fuse will be blown in the under hood relay center, #9 position. Does anyone know what all is on this circuit? I am at wits end here! According to what little I have been able to find on this, that fuse is for the PCM? Anyone have any input on this?

 

I have no idea what you are calling fuse #9 as the fuses in that box go by letters.
Can you tell me the letter?


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My owners manual has a diagram legend, which was referencing the fuses by #'s, but the fuse I am referencing is called "I" in your picture. According to the owners manual it says it is PCM/PCM POWER RELAY......?

 

Well fuse “I” powers all the solenoids except the starter solenoid along with the coil for the fuel pump relay. It also powers the power for the computer and the transmission.
In other words fuse “I” is the power source for the Red #361 wire.

From the 1993 Ford wiring diagrams:




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Thank you so much, hopefully with this info I can get it running again tomorrow! I have never ran into this before, and it really had me stumped, not having any info on the circuit, or a wiring schematic

 

I hooked a scantool to it earlier because it seemed it shifted really early to me now that I have this problem, but all I came up with was a 332 which is for the EGR valve. I noticed that the relays both (fuel pump, and PCM) feel rather warm, I don't know if that is normal or not? I'll check red wire 361 end to end tomorrow, and try to see if there are any tests I can do on the components in this circuit.

 

I'm having the same problem. What could it be? I'm not good with wiring.

 

Let me be more specific. 1993 f150 4.9 auto. Was idling and died. Fuse 9 under hood was blown. Replaced it and soon as key is turned it pops every time. Any ideas?

 

You will just have to disconnect all of the items that fuse "I" feeds. Then plug them back in until fuse "I" blows again. Fuse "I" was covered in the text I posted above.



Fuse "I" supplies the 361 RED wire.




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Ok I'm gonna do that. Thanks