Engine won’t shut off

[B E N]

If the upfitters are that delicate they only meant to trigger a relay, 20ga wire should be kept to a max of 5A, or about 60w per upfitter. Rigid claims their DSS in driving pattern consumes 4.07A @14.4v, which is 4.887@ 12v. Meaning if your running more than a single set of pods off of your upfitters you need to invest in a relay. There are pre-wired kits available that take about 20 minutes to install if your meticulous with the zip ties.

I don't understand why ford put 20a fuses behind 20ga wire.

 

[FordTechOne]

If the upfitters are that delicate they only meant to trigger a relay, 20ga wire should be kept to a max of 5A, or about 60w per upfitter. Rigid claims their DSS in driving pattern consumes 4.07A @14.4v, which is 4.887@ 12v. Meaning if your running more than a single set of pods off of your upfitters you need to invest in a relay. There are pre-wired kits available that take about 20 minutes to install if your meticulous with the zip ties.

I don't understand why ford put 20a fuses behind 20ga wire.

To clarify, here are the Aux Fuse ratings and wire gauges:

Aux 1 - 15 A Fuse - 16 gauge wire
Aux 2 - 15 A Fuse - 16 gauge wire
Aux 3 - 10A Fuse - 20 gauge wire
Aux 4 - 10A Fuse - 20 gauge wire
Aux 5 - 5A Fuse - 22 gauge wire
Aux 6 - 5A Fuse - 22 gauge wire

As a general rule in automotive electrical, the continuous load of a circuit should not exceed 80% of the fuse rating. If the lighting was drawing 4.89A through a 5A fuse, it's right at the maximum. Any high resistance at the connection between the factory aux circuit and aftermarket circuit could generate enough heat to melt the wire.

 

[FordTechOne]

How can it melt without the current draw exceeding the fuse? These are intended to be used exactly the way you had it set up. The interior switches are already wired to an OEM relay, right?

High resistance or circuit overload. It is important to remember that a 5A fuse will not open at exactly 5A; if the lights were drawing 5A or slightly more 5A for 2 hours, combined with any heat generated from resistance within the connections, it can create enough heat to melt the wire. I would be curious to see what OP's light setup draws when connected to a 12V source for 2 hours; that may help with determining what lead to the failure. This test could be accomplished relatively easily by connecting the Rigid light's 12GA wire to the vehicle's battery through a fused connection and installing an ammeter in series to measure current.

 

[FordTechOne]

I'm probably the last guy who should talk about automotive electrical wiring but I don't understand how simply connecting to wires intended for aftermarket lighting can be the cause? Were they all wired to either wire 5, or wire 6?

Even if they were, as @Droid suggested, isn't there a fuse or relay already built into the system? This sounds like another case of, "Let's blame it on the modifications to earn our dealership more money."

The only thing that can melt a circuit is high current or high resistance caused by the aftermarket lighting. Neither is warrantable. If Ford, or any other OEM called back that harness, they'd be charging the dealer back for the claim.

Can anyone guess how many Raptors, including mine, have aftermarket lights installed as designed without melting the harness....yet? And why does Ford use the smallest gauge wires found on the truck for the upfitter switches? I'm not buying their explanation.

There, now that I got that off my chest...Thanks for sharing @Dan Larsen. I feel your pain!

Ford uses the appropriate sized wire per industry standards for the current rating of the fuse. See my earlier post with the aux fuse and wire specs.

 

[The Car Stereo Company]

@Dan Larsen you said you have 3 sets of lights. how were they wired?

 

[The Car Stereo Company]

As a general rule in automotive electrical, the continuous load of a circuit should not exceed 80% of the fuse rating

cant tell you how many times i have said this.

 

[JohnyPython]

cant tell you how many times i have said this.

I used this rationale since its the same in household wiring.

 

[Jakenbake]

cant tell you how many times i have said this.

So to clarify, you are saying the fuse is sized for the maximum current the wire can handle? The load on the circuit should therefore not exceed 80% of the wires maximum allowable load.

I typically put a fuse on a line (as in on my RTMR) that is just big enough to handle the load.

So for the upfitters, you are saying stay below 80% of their rating?

 

[JohnyPython]

So to clarify, you are saying the fuse is sized for the maximum current the wire can handle? The load on the circuit should therefore not exceed 80% of the wires maximum allowable load.

I typically put a fuse on a line (as in on my RTMR) that is just big enough to handle the load.

So for the upfitters, you are saying stay below 80% of their rating?

10A use 8A max.

 

[Jakenbake]

10A use 8A max.

I’m with you on that.

But am just verifying that the 10 amps that is being referred to is the maximum for the line.

Meaning a hypothetical line can handle 20 amps but is fused for 10, then you could run a 9.7 amp item off of it no problem.

but if it is safe for 20 amps and fused for 20 amps, you would want to honor the 80% for it.