Fuse 33 Blowing - 07 F150
02-26-2017, 12:05 PM
#1
Fuse 33 Blowing - 07 F150
I have combed the threads here and found that people have had similar issues to mine but were lucky enough to find the cause of the problem. I have not been so lucky so I am asking for help. Here's the story:
Last Friday night my son calls me late (a call you don't want on a Friday night) to tell me his truck just died while driving home. After a long slow tow home I started troubleshooting thinking it would be as easy as a failed alternator. No such luck.
I pulled the codes and received P0734, P0759, and P0962. All of these directed me to fuse #33. Sure enough, it was blown. I replaced it and tried to start the truck. It blew again. I then realized it was blowing when the key was turned to ON. From here I start to learn about this circuit which powers the 8 coil packs, shift solenoid, and CMS 12 and 22 (I don't know what CMS 12 and 22 are).
I was directed by a couple of other threads to unplug all coils and the 16 pin connector that splices off the middle harness of the PCM. I did this, and no fuse blown. I left the coils unplugged and plugged in the 16 pin connector, fuse blows. This rules out the coils. To make a long story short, I have now done this same test by unplugging the transmission connection, and O2 sensors with the same result. It seems the issue happens when i connect the 16 pin connector. The problem is, I don't know how to trace the issue. It is very hard to see and go wire by wire. I also wonder if it could be related to the FPDM under the spare tire. This seems to be a common problem too but I don't want to just throw parts at a problem such as this.
Does anyone have a similar issue or solution to try. The truck is dead and I want to try everything I can before I take it to someone smarter than me.
Thanks!
Randy J.
Last Friday night my son calls me late (a call you don't want on a Friday night) to tell me his truck just died while driving home. After a long slow tow home I started troubleshooting thinking it would be as easy as a failed alternator. No such luck.
I pulled the codes and received P0734, P0759, and P0962. All of these directed me to fuse #33. Sure enough, it was blown. I replaced it and tried to start the truck. It blew again. I then realized it was blowing when the key was turned to ON. From here I start to learn about this circuit which powers the 8 coil packs, shift solenoid, and CMS 12 and 22 (I don't know what CMS 12 and 22 are).
I was directed by a couple of other threads to unplug all coils and the 16 pin connector that splices off the middle harness of the PCM. I did this, and no fuse blown. I left the coils unplugged and plugged in the 16 pin connector, fuse blows. This rules out the coils. To make a long story short, I have now done this same test by unplugging the transmission connection, and O2 sensors with the same result. It seems the issue happens when i connect the 16 pin connector. The problem is, I don't know how to trace the issue. It is very hard to see and go wire by wire. I also wonder if it could be related to the FPDM under the spare tire. This seems to be a common problem too but I don't want to just throw parts at a problem such as this.
Does anyone have a similar issue or solution to try. The truck is dead and I want to try everything I can before I take it to someone smarter than me.
Thanks!
Randy J.
