12- volt fuse replacement

[its2kito]

My 7-way trailer plug has shorted. Volt meter readings are 1=0.6 ;3=11.0 ; 4=0.09 ; 5=13.44 ; 6=16-22 ;center (backup light prong)=0.16-0.20
I’m scheduled to go camping and tow my trailer in two days. Tesla doesn’t respond to my calls or service emails. I’ve already tried a hard truck reset. It is most likely the F131, 15 amp fuse for the 12- volt system.
Question: can I change the fuse without voiding the warranty?

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[hemiarch]

Don’t know if this is a feasible option for you or if the same is true where you live but I’ve often had success physically going to the service center and asking for help from a service advisor. There is a lot of stuff they will do on the spot or they can help you schedule a mobile appointment.

 

[mongo]

My 7-way trailer plug has shorted. Volt meter readings are 1=0.6 ;3=11.0 ; 4=0.09 ; 5=13.44 ; 6=16-22 ;center (backup light prong)=0.16-0.20
I’m scheduled to go camping and tow my trailer in two days. Tesla doesn’t respond to my calls or service emails. I’ve already tried a hard truck reset. It is most likely the F131, 15 amp fuse for the 12- volt system.
Question: can I change the fuse without voiding the warranty?

What was the initial symptom?
I don't know anything about a fuse nor 12V system, the trailer connector has its own module that runs off 48V

I assume you are using this numbering system for the trailer pinout:

What mode were you in when you took the readings? Was trailer mode on? Was trailer light test on?
I think the values look good if idle and unloaded. Left and right brake should be off (0.6, 0.09), backup off(0.16), running light on (16-22), Aux on (13.44), brake at a low value (11) for detection.

Once the sun rises here I can verify values in my truck, but it should be self protected and hard to actually short.

 

[mongo]

Once the sun rises here I can verify values in my truck, but it should be self protected and hard to actually short.

@its2kito, I checked my truck and get the same voltages in trailer mode with the lights on. Did you try the trailer light test mode?

 

[eser50]

My 7-way trailer plug has shorted. Volt meter readings are 1=0.6 ;3=11.0 ; 4=0.09 ; 5=13.44 ; 6=16-22 ;center (backup light prong)=0.16-0.20
I’m scheduled to go camping and tow my trailer in two days. Tesla doesn’t respond to my calls or service emails. I’ve already tried a hard truck reset. It is most likely the F131, 15 amp fuse for the 12- volt system.
Question: can I change the fuse without voiding the warranty?

If I recall correctly, during one of the interviews with Munro, they said the Cybertruck doesn't have any traditional fuses and are all self-resetting E-Fuses

 

[mongo]

If I recall correctly, during one of the interviews with Munro, they said the Cybertruck doesn't have any traditional fuses and are all self-resetting E-Fuses

Yup, no user serviceable fuses. What few there exist are in the HV system
(And maybe internal to the media control unit/ FSD computer)

 

[its2kito]

Thank you for all your replies and effort. The 7-way plug is a 12-V system and has its own fuses under the frunk. But it wasn’t the fuses. Soooo, this was the problem(s):
1. Notification VCTrailer_a202 was a software update, if there is incorrect distribution of weight at the hitch. So I removed the load at the back of my truck; 2. When the emergency brake disconnect device on the trailer was I oiled and verified (I do this once every couple of yrs), the pin may not have been fully seated.
Everything works NOW. AI app helped me solve my own problem !! On my way to my camping vacation now

 

[CT_AZ_4x4]

Thank you for all your replies and effort. The 7-way plug is a 12-V system and has its own fuses under the frunk. But it wasn’t the fuses. Soooo, this was the problem(s):
1. Notification VCTrailer_a202 was a software update, if there is incorrect distribution of weight at the hitch. So I removed the load at the back of my truck; 2. When the emergency brake disconnect device on the trailer was I oiled and verified (I do this once every couple of yrs), the pin may not have been fully seated.
Everything works NOW. AI app helped me solve my own problem !! On my way to my camping vacation now

 

[its2kito]

PS
I’ve solved the problem :
1. I first asked AI to answer the question of CT Notification VCTrailer_a202; the AI said a software update earlier in 2025 added a weight distribution safety so that the hitch weight isn’t too much, so moving my accumulations from the back of the CT to the back seat floor resulted in a positive “trailer light test”. That confirmed that it wasn’t a 15 amp fuse.

So everything was go for driving from the trailer storage location to my home. A notification of fault in turn signals and trailer braking appeared just before arriving home. But the fault warning was intermittent.

2. Intermittent fault notifications suspected a plug contact issue. Sooo, when I arrived home, I sanded the trailer plug contacts and sprayed contact lubricant.
YES !!! Problem solved. The Cybertruck was perfectly fine, the trailer plug contacts were corroded. Attached are pics of sanding and contact lubricant.

 

[its2kito]

 

[its2kito]

 

[mongo]

1. I first asked AI to answer the question of CT Notification VCTrailer_a202; the AI said a software update earlier in 2025 added a weight distribution safety so that the hitch weight isn’t too much, so moving my accumulations from the back of the CT to the back seat floor resulted in a positive “trailer light test”. That confirmed that it wasn’t a 15 amp fuse

The AI hallucinated
There isn't a 12V fuse, 15A or otherwise.
The overweight detection is separate from the trailer control module functionality.

 

[CyberGus]

It is most likely the F131, 15 amp fuse for the 12- volt system.

the Cybertruck doesn't have any traditional fuses and are all self-resetting E-Fuses

The AI hallucinated
There isn't a 12V fuse, 15A or otherwise.

Cybertruck has no fuses, other than the pyro fuses in the pack. (Don't mess with those lol)

The AI confused the Cybertruck with the Model X, which does have traditional fuses (specifically, a 15A fuse for the trailer lights in slot F131).

https://teslamotorsclub.com/tmc/threads/no-12-volt-power-to-tow-package-trailer-outlet-plug.303797/

 

[ke6jph]

As a frequent visitor to our local boat launch ramp I was having problems with the trailer lights after recovering my boat. (Water on the plug )
The fix was to pack the trailer plug and receptacle with dielectric grease.
When not pulling the trailer I use this cap to keep the plug clean.
GR Innovations | 7 Way Plug Cover | Superior 7-Pin Trailer Plug Protector | Universal Fit | Handy Tethered Cord | Plug Saver | USA-Made | Essential for Trailers & RVs. (On Amazon).

Sorry for the bold text I have not had to copy and paste from Amazon before

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