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Senior Member
Joined: Mar 2012
Posts: 295
From: SW Florida
I haven’t had time to work on it again until today. I spent an hour after work. I’ve replaced the fpcu because it had the usual corrosion inside, and I wanted it replaced either way. Today I tested for power at the fpcu plug. The relay up front is not switching and supplying power when the key is on. I can jump power across the relay and the fpcu harness has power in all of the right places. At this point I am starting to look at the aftermarket alarm system, but that has to be another day! It’s something stupid, but I’ll find it! I’m going to pull the main alarm box to the aftermarket setup and open it up to see if it has corrosion inside. The remote works, the remote start works, but something is keeping the truck from switching that relay. Open to suggestions! 
Have you tested the relay?
Senior Member
Joined: Jul 2012
Posts: 8,999
From: C-Town
What relay #? Did you check fuse #33?
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Member
Joined: Mar 2021
Posts: 42
I’m not home right now, but I’m assuming #33 is the 20a fuse I was referring to above that is labeled fpcu? If so, it was blown when the truck arrived and was the first thing I replaced.
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Member
Joined: Mar 2021
Posts: 42
Sorry missed the part about the relay. I replaced the relay to the fpcu, I’d have to be at home to read the panel for the relay number. I believe it’s labeled STOP.
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Member
Joined: Mar 2021
Posts: 42
Yes that is correct, it is not labeled for the fuel system but it is in fact a relay controlling power to the fpcu. I think in that chart it’s #66, I can confirm when I’m at home. You just jump
power from I think 35 to 80 across the relay and the fpcu gets power. I believe because this relay isn’t switching the alarm is cutting power to it for one reason or another. 🤷♀️The aftermarket alarm wiring is a bit of a mess. 👀
power from I think 35 to 80 across the relay and the fpcu gets power. I believe because this relay isn’t switching the alarm is cutting power to it for one reason or another. 🤷♀️The aftermarket alarm wiring is a bit of a mess. 👀
