2017 F150 Lariat, it has the factory sony amp with factory sub. My son added a sub and amp a couple months ago and it has been fine. On monday he said his radio quit working, so after checking all fuse (none blown) i started looking at connection around speakers and amps(after i pulled head unit out to inspect for loose wire/connections). I noticed the top black and purple wire at sony amp is melting and connector is melted. I took trick to stereo shop figuring he hooked something up wrong after 2 hours of them looking at it they said everything was wired correctly and it would be a vehicle issue.

So i need help in how to trace down my issue and what repair pigtail i need to order to fix connector/wire. I do have a multimeter and somewhat familar with and wiring. Any help or known issues with these amps causing this would be great!

 

Forgot to say when i wiggle the burnt wire the radio works on and off.

 

If you want to buy the pigtail, it is Motorcraft WPT-959 [Ford 3U2Z-14S411-BDAB].

The connector is a Yazaki 7283-6456-90. The tin plated terminals are as follows:
7116-4100-02 (22-20AWG)
7116-4101-02 (18-16AWG)
7116-4780-02 (22-20AWG)
7116-4781-02 (18-16AWG)

 

thank you, do you happen to know what that black and purple wire goes to so i can try to figure out what wrong

 

The BK-VT is a 14 AWG ground wire and goes to G302, G302 is at the LH C-pillar.

 

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The burnt lead in your photo highly suggests a >resistance connection< inside the connector.
At high Current flow, the voltage drop across the resistance caused very high heat that followed outside and melted the wire insulation.
For proof of this condition, Power in watts = voltage dropped across that resistance... times.... the Current passing through that Resistance.
For example: if the voltage dropped across the >poor connection< is 8v out of normal system 14v at 4 amps flow would = 56 watts of power. That is enough to heat the wire for a short distance outside the connector.
In a way, your lucky not to have burned the truck down if the bundle was twisted closer together or some other Flammable material was in contact with that area.
Good luck.