Horn fuse and alarm

[sonya1272]

I just purchased a 1999 Boxster. The car is in great shape and I love it! The horn is not working so I stopped by a local mechanic. He checked and noticed the fuse was missing. He inserted a new fuse and the car alarm went off. We removed the fuse to stop the noise so I was wondering if this is an easy fix or a bigger electrical issue? Any help or advise would be greatly appreciated. Thank you

[mattatk]

Looked at the workshop manual & it implies that, if there is a fault/sensor tripped when you arm the alarm (picked up in initial 10 second period), it will isolate that sensor & arm the other sensors & lets you know by beeping the horn, turning on the interior light for 2 seconds & double flashing on the alarm LED on the dash.

The sensors monitored are:

1. left door,

2. right door,

3. front hood,

4. rear hood,

5. oddments' tray,

6. convertible top compartment lid,

7. radio,

8. infra red sensor of passenger compartment (with hood closed),

9. alarm horn (removal),

10. activation of the ignition switch,

11. invalid transponder in key in ignition,

12. interruption of voltage to alarm control module.

I am wondering if cycling the fuse in & out might trip the last mentioned sensor (12)?

Try putting the fuse back in & cycling the alarm off & on with your key. If the alarm keeps sounding, then there must be stray electricity somewhere, short circuit or faulty ground, or the alarm control module is faulty. Somehow the alarm isn't isolating the faulty sensor & turning the other sensors on.

Otherwise if, after 10 seconds, you get the abovementioned signals (LED double flashes, etc) then the system is telling you that it has armed the alarm sensors, excluding one or more faulty sensors. Then you can use the process of elimination to check each sensor, by arming the alarm & tripping one sensor at a time to see if it sets the alarm off. I have heard online that the oddments' tray sensor can be temperamental, the tray needs to be pushed down to firmly to activate the microswitch.

Good luck!!

BTW, are you referring to the 15A fuse in the actual alarm control module? (lives in between the two electrical connectors on the module)

Edited April 12, 2011 by mattatk

[sonya1272]

Thanks for the information! Actually it is the 27 fuse I believe. My key head is bad on my remote I wonder if replacing might solve the alarm issue?

Looked at the workshop manual & it implies that, if there is a fault/sensor tripped when you arm the alarm (picked up in initial 10 second period), it will isolate that sensor & arm the other sensors & lets you know by beeping the horn, turning on the interior light for 2 seconds & double flashing on the alarm LED on the dash.

The sensors monitored are:

1. left door,

2. right door,

3. front hood,

4. rear hood,

5. oddments' tray,

6. convertible top compartment lid,

7. radio,

8. infra red sensor of passenger compartment (with hood closed),

9. alarm horn (removal),

10. activation of the ignition switch,

11. invalid transponder in key in ignition,

12. interruption of voltage to alarm control module.

I am wondering if cycling the fuse in & out might trip the last mentioned sensor (12)?

Try putting the fuse back in & cycling the alarm off & on with your key. If the alarm keeps sounding, then there must be stray electricity somewhere, short circuit or faulty ground, or the alarm control module is faulty. Somehow the alarm isn't isolating the faulty sensor & turning the other sensors on.

Otherwise if, after 10 seconds, you get the abovementioned signals (LED double flashes, etc) then the system is telling you that it has armed the alarm sensors, excluding one or more faulty sensors. Then you can use the process of elimination to check each sensor, by arming the alarm & tripping one sensor at a time to see if it sets the alarm off. I have heard online that the oddments' tray sensor can be temperamental, the tray needs to be pushed down to firmly to activate the microswitch.

Good luck!!

BTW, are you referring to the 15A fuse in the actual alarm control module? (lives in between the two electrical connectors on the module)