No backup light power?

Tiny
SQUIGGS80
  • MEMBER
  • 2013 FORD F-150
  • 5.0L
  • V8
  • 89 MILES
The truck listed above is an STX. No reverse lights at all, no trailer reverse lights either.
But all fuses and relays are good, and I moved the breaknout ground to a new clean spot on frame. Which ground is good on light socket but no power to blue and white wire either side or trailer hitch pin.
Saturday, April 8th, 2023 AT 2:44 PM

1 Reply

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,179 POSTS
Hi,

I'm looking at the reverse lamp wiring schematic. I'm seeing two fuses and one relay. If I am reading them correctly, fuse 43 and the relay are both in the battery junction box and appear to be specific to the trailer lamps.

Fuse 15 (interior left kick panel) is what powers the lamps and triggers the relay.

Now, I attached the wiring schematic below, so you have a reference. If all fuses are good, then either we have a breakdown in the computer area network, a broken wire, a splice that has failed, or a connector that is damaged or has come apart.

Since both the rear lamps and trailer connector have no power, the failure is between splice 120 (S120) and the reverse lamp FET (field effect transistor) at the body control module. I would locate S120 (blue wire with white tracer) first to see if there is power present at that point.

If you look at pic 3, it provides the location of the splice.

Let me know what you find or if you have other questions.

Take care and Happy Easter,

Joe

See pics below. Note: I had to cut the schematic in two, so it was readable for you. I did overlap the two so you can follow from one to the next. Also, sorry about all the yellow marks. I was marking and thinking at the same time. LOL
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Saturday, April 8th, 2023 AT 8:55 PM

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