Alarm Keeps Going Off Randomly
 

Have an '06 LR3 with an alarm that keeps going off without any reason I can see. Tried replacing the battery as it was the original, still no fix as I read a low battery can trigger the alarm. Could it be the battery in the fob? If so, how to open to change? Or some other reason? Checked hood latch several times, am in and out of doors and tailgate all the time so those are shut consistently, and getting no other error messages.
Neighbors would appreciate some suggestions too.

Thanks.
Candace

Hood Switch. Just had mine replaced. Common Problem It's on the passenger side hinge lock. Mine was really grimey. I was thinking if I got som PB Contact Cleaner and sprayed it in there, it would have worked. But since I just picked up the truck and they are waiting on the settlement check form my totaled Disco, they replaced it gratis. Otherwise $200+

Hood switch
 

You can replace the Hood Latch Sensor for $20 and 30 seconds of time. So find it online, pretty simple. I got mine from britcar.co.uk, but there are plenty of other vendors. For now unclip the sensor from the latch housing and then unplug the wire running to it. Use a short piece of wire or a paperclip as a jumper to close the circuit. Put one side in each of the plug terminals and tape it up until you get the sensor in.

Ours was going crazy for some time. While in for warranty service, they replaced it as well. Problem solved.

Lots of little switches and sensors have been acting up; rear hatch switch always thought it was open, washer fluid sensor always thought it was empty...

this post.. SOOOO helpful.. on stage one (the paper clip).. looking to find new sensor.. in Canada..

I love this website. I order me one on ebay. $25. Just put the part number in (LR041431).

I got one from British Atlantic on line. $15.99. It didn't resolve the problem though. Help.

Here is the wiring diagram to the LR3 alarm. Some sensors are part of the door lock mechnaics. Each sensor is "normally open" and shorts to ground to trigger. A skinned wire can do the same. Sometime it can be a pinched cable that leads from door to truck. You can also disconnect the connector and read for ohms to ground toward the sensor, any stray readings are suspect. I don't know how sensitive it would be to water in a connector, etc. You can also unplug the horn to keep peace with the neighbors while you work this out, just re-connect before you drive away.

I am having the dreaded random alarm issues. Mine seems to only go off when certain conditions occur.

After the car has been parked, It is cold outside (Night Time) and after the sun begins to warm up the ambient temperatures, the alarm goes off. Maybe something having to do with expanding and contracting as temperature changes.

Is there a way to just disable the hood switch completely?

just disconnect it
 

The hood switch is either what is called normally open or normally closed. Regardless, when the hood is open, the switch closes and completes a circuit to ground and hence the alarm goes off. That is why there is some thought about the cable to the switch being cut such that it is already grounded regardless of if the hood is open or not.

Anyway, if disconnecting the cable from the switch does not silence things, then jump a wire between the two terminals. That will ground the circuit and then things will be noisy or not. If not, then you have a problem with the cable and not the switch.

There is a 17 page pdf as one of the files in the album link below that explains how the locking/alarm system operates. Opening the hood grounds the circuit and should cause the alarm to sound.

DISCO3.CO.UK Photo Gallery - Power Window and Door Lock Circuits