Light Issue

[USNA_Stang]

Hey guys,

So ran into a problem this afternoon. My car sits for a week or 2 at a time, so when its parked, I disconnect the battery. Today when I reconnected the battery, the headlights came on before I had even put the keys in the ignition. This is the first time this has happened and I'm not sure why. Any ideas what it could be?

Some background: 07 Mustang GT/CS. Optima Yellow-top Battery. The battery died a month or 2 ago, but this is the first time I have had problems since.

 

[JeremyH]

Do they turn back off when you shut and lock the door?

 

[USNA_Stang]

Do they turn back off when you shut and lock the door?

No they stay on.

 

[gray06gt]

I think you can program the car to where they turn the lights off but since you disconnect the battery it has to relearn everything is my guess

 

[JeremyH]

Ensure light switch is off check the relay and suspect water intrusion at the SJB.

 

[USNA_Stang]

Ensure light switch is off check the relay and suspect water intrusion at the SJB.

Light switch is off. SJB? relay would be fuses right?

 

[JeremyH]

You have relays and fuses. Fuses protect the circuit so if the fuse was blown the lights wouldn't work at all. A relay could stick causing power to be applied when the switch is off. Or you have water on the sjb grounding the circuit. (our lights work on reverse polarity so power is always there and ground is switched on and off)

Your users manual shows you where the fuses and relays are and what they are for.

It is common for water to leak through the cowl into the passenger side and get on the sjb (smart junction box) which is in the passenger side kick panel. You can unbolt it and look for water. If you have signs of moisture or corrosion you may have this problem. It can cause all kinds of electrical gremlins.

 

[07 Boss]

The SJB is in your passenger side foot well. There is a little door on the kick panel. This controls all of your functions like interior and exterior lighting, HVAC, door locks and such. Basically anything that doesn't have to do with engine management.

 

[USNA_Stang]

Awesome! Thanks for the help guys! I'll take a look at this and see what I can find.