It recently got really hot and humid out and all of my electrical parts in my 06 Mustang GT work then they dont work, then they work again, like my A/C, headlights, blinkers, power windows, radio, and also my parking break will think its on but its not, it will just beep until i stop.

It got worse as the days went on, my dash said "check charging system", "check brake system", and "check ODO meter error". I brought it in and they didnt find anything wrong with it, the car was a salvage title, it has rust and mud in parts of the car. Do you think that non ford parts were installed or rust is blocking a signal or something, it worked all winter in Minnesota completely fine too.

 

Inside the cabin on the passenger's side to the right of your feet there's a plastic panel with a door. Behind that door is your SJB (smart Junction Box - The car's computer). Take that door off, or better yet take that whole panel apart and disconnect the SJB and check for corrosion in the connections.

"the car was a salvage title, it has rust and mud in parts of the car." was it a flood car? Sounds like it. If it wasn't a flood car, then you may want to check out this thread. You'l also find a bunch of similar threads with a quick search.

 

Flood car more than likely. All those shiny elec. pin connectors are starting to rust. Causing intermitant shorts. I would guess It would only get worse . Good luck.

 

I concur with the above. In the unlikely event that bad terminations is NOT the problem, have your alternator and battery checked out. It could be an intermittent low voltage issue now that you're probably running the A/C more often.

 

I just got it back from the shop, and they used this computer system to see if any codes came up that would indicate bad issues and nothing came up, because when they were looking at it, everything was working fine, So i guess i have to wait until it acts up again then bring it in. It works fine now, it must have been the hot humid weather and rain that passed through the past couple of days. They checked all the wires too and nothing looked out of whack.

 

Remove the passengers side door sill and kick panel.
They pull off with clips.
Pull the carpet and pad back.
Check for signs of water intrusion/damage.
The SmartJunctionBox is on the kick panel
right below a well known water leak area.
Sounds like your SJB is corrodded internally.
It controls the items you are describing as
having glitches.

 

Its been fine so far, but if it happens again, I will definitely look into the SJB area, thanks!

 

Happens again?
Its a fricken time bomb.
Dont sit back and wait for it to explode
at the worst most possable moment.
Nip it in the bud. Nip it in the bud.

 

Why do I suspect we'll be hearing from the OP again real soon?

 

So i ended up bringing it to a Ford dealership and they told me exactly what you guys have been telling me, my SJB is corroded, and the car was completely submerged in a flood or something therefore all the wires and electrical areas are coroded due to the hot humidty and didnt show up in the winter because of that. Its gonna cost me about 3100 bucks, but it will be totally worth it because i still got the car for 8 grand less than it was worth. Thanks for all your help and suggestions.

One more thing, i ask them also to check on my fuel gage and oil gage, it only shows that i have a 3/4 of a gas tank full, when its actually completely full. Im afraid to go below empty just incase my tank is a mini tank or something. My instrumental cluster is being replaced too, would that help that situation or is that another area?