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[tigers_gonads]

Car alarm is playing up again.

The power sounder is removed.
When it alarms, the indicators flash but no horn.

Plugged the laptop in and these came up..............

DTC 0120
Horn connection open circuit.

Okay, I understand why it isn't making a noise but is the horn fault enough to repeatedly cause the system to trigger every 10 minutes or so ?

Car isn't in use much at the moment so battery voltage may be slightly low but battery condition is good as far as I know.

Went off that many times last that by this morning, the battery voltage was down to 11.8 volts so its been on charge for the last few hours.

This might not be connected BUT a few days ago, I took the missus to work in the car and for the first few presses of the brake peddle, I heard a faint buzzing sound coming from the back of the car 

Its not a option around here to leave the car unlocked so any ideas will be greatly appreciated 

[RobG]

Assuming it`s the estate, check the connections on both rear quarter windows

[tigers_gonads]

Assuming it`s the estate, check the connections on both rear quarter windows

All connections okay Rob 
Also checked the continuity of the film on the window, no problem found.

I did have the same problem last year.
I removed the bonnet switch at the time and that seemed to sort things out 
As a experiment, I refitted the bonnet switch after I removed the charger about 6pm earlier.
Upto now, the alarm has behaved itself 

I'll see what happens over night and report back here 

[tigers_gonads]

Well no false alarms last night and no buzzing noises when I press the brake peddle so looking into a possible earth fault somewhere 

[tigers_gonads]

Right, finally got a hour to pull the scuttle off and test this alarm horn to find the horn coil is open circuit 

I take it that while going through the setting sequence, the box of tricks puts a pulse of current down the through the wire to the horn as a test 

Anybody know what the internal resistance of the coil is by any chance ?
Thinking of a temporary fix with a little resistor so I can set the alarm / deadlock until I can source a replacement 

[RobG]

Right, finally got a hour to pull the scuttle off and test this alarm horn to find the horn coil is open circuit 

I take it that while going through the setting sequence, the box of tricks puts a pulse of current down the through the wire to the horn as a test 

Anybody know what the internal resistance of the coil is by any chance ?
Thinking of a temporary fix with a little resistor so I can set the alarm / deadlock until I can source a replacement 

PM sent

[TheBoy]

The horn being open circuit, like the missing PS, does NOT cause the alarm to activate.

You need to read the Alarm log codes (not fault codes)