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Chris (aka- Moose)
Chris (aka- Moose), Technician
Category: Ford
Satisfied Customers: 43972
Experience:  16 years experience
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2008 Ford Expedition alarm goes off for no reason. No one

Customer Question

2008 Ford Expedition alarm goes off for no reason. No one even the dealer can figure it out
JA: Have you tried locking and unlocking the driver's side door using the key itself?
Customer: Several times
JA: Are you fixing your Expedition yourself? What have you tried so far?
Customer: I've had dealer & other mechanics try to figure it out. Reset computer, clearing 2 pages of low voltage codes. Put in new battery (2nd)
JA: Anything else you want the mechanic to know before I connect you?
Customer: It has a ford factory remote start also. Installed at dealer
Submitted: 1 month ago.
Category: Ford
Expert:  Chris (aka- Moose) replied 1 month ago.

Welcome, I'm Chris (aka Moose) I prefer to work when others don't, I am here around lunch and after dinner till after midnight.

Is this the scenario. You exit the vehicle, lock it. Later on the horn and lights are pulsing?

Any current trouble codes?

Customer: replied 1 month ago.
Only the horn, no lights. Happens whether I use the fob to lock the doors or the inside lock button or the keyless entry buttons. The cleared codes (almost 2 pages) were primarily low voltage, why Tech replaced battery and reset computer.
Expert:  Chris (aka- Moose) replied 1 month ago.

A low voltage code can cause this, which is why I wanted to make sure there are no codes now.

When you press the panic button do the lights flash?

Any aftermarket electronics on the vehicle?

While driving do you ever get a false door ajar warning or the courtesy lights coming on for no reason?

Customer: replied 1 month ago.
No false door ajar or courtesy lights
Horn only on panic button
No aftermarket electronics
Expert:  Chris (aka- Moose) replied 1 month ago.


Since there are now no codes, no door ajar issues, no battery concerns.

I would check for a hood closed switch that is out of adjustment.

Diagnosing this system is tough when the perimeter theft system goes off. Sometimes locking the vehicle and then 30 minutes later push and pull on each opening will trigger an alarm and tell you where to look. Sometimes you have to hook up a volt meter to the power outlet with a video camera to watch it and inside the cab to see what is happening.

This is my 1st answer, but does not have to be my only answer. You the website and myself expect you to have a ~~~5 STAR EXCELLENT~~~ experience with my help. Please let me know if you are pleased by selecting a star rating above or by replying and saying your pleased. Not rating or rating 1-2 stars does not benefit you nor me in any way. Follow up and reply as often and when needed, there is no extra charge to do so.

Thanks Moose.

Customer: replied 1 month ago.
How about the back window? I had a break in and the back window was smashed & replaced. Bad connection?
Expert:  Chris (aka- Moose) replied 1 month ago.

That would be included in the comment I made on "push pull on each opening"

Yes this is a possible cause but I would expect a warning light when it falsely shows open while closed and driving.

Trust me this is a hard issue to figure out, as you can see from the prior shops giving in.

One thing I forgot to mention. This alarm goes off when it sees a voltage drop. It thinks someone has broken a window, reached in and opened a door. So any sudden voltage drop will cause this.

Expert:  Chris (aka- Moose) replied 1 month ago.

Hello again Chris here,

  • I am following up with you to see if you got everything you needed from my answer. We're you pleased with my help?
  • If you were not pleased with my help, please let me know by replying so I can help more.
  • This post is coming up on the 7 day mark where it times out. When a post times out, that means it's no longer on my active list (you reply and I may never know it.)

Thanks Chris