Number 48 fuse keeps blowing?

Tiny
STORMILYN
  • MEMBER
  • 2007 FORD FIVE HUNDRED
  • 2WD
  • AUTOMATIC
  • 185,000 MILES
My car wouldn't crank one day, and we found fuse number 48 was blown, so we changed it and it worked for like 2 weeks and it blew again. So, I tried to replace it but every time I tried to start the car it blows that fuse now!
Sunday, November 5th, 2023 AT 2:13 PM

1 Reply

Tiny
CANNON1349
  • MECHANIC
  • 581 POSTS
Hello and thanks for your question!

Fuse #48 looks like it sends power to the TCM, EVMV, Canister vent, ESM, Exhaust Gas Oxygen heaters, and A/C clutch. This should be a 10A fuse.

If the TCM has no power then the car won't start as it won't know if it's in park or neutral, but because this fuse gives power to several parts of the car, a short in any of these can blow this fuse and cause a problem with starting.

First, do you have any engine codes present? Please refer to this guide below:
https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Second, verify that the fuse blows only when starting the car, versus leaving the key in the on position.

Fuse #49 shares a junction with #48, and it controls the PCM, Injectors, Ignition coils, and Mass Air Flow (MAF) sensor. There is a breakout near the fuse box, check for any exposed wires and the like. I will attach some wiring diagrams tracing the circuit, and then we can begin tracking this down.

Again, if you have any electrical-related codes in the PCM it will help us narrow this down.

Let us know!
William
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Sunday, November 5th, 2023 AT 6:41 PM

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