Sunday, July 24, 2011

Land Rover Hood Sensor - Take 2

Last weekend I figured out how to remove the alarm hood sensor. It came right out. Then I used a DMM continuity tester to see if the integral micro-switch was working. Touching the DMM leads to the contacts in the connector, I worked the switch about a dozen times by pressing on the curved metal thingy (see photo). It worked fine. So I pulled on that curved metal spring to expand it a bit, thinking that maybe it's become compressed over time from normal use. Then I reinstalled it and connected it up (removing my short circuit I'd installed a few weeks before).

Well, that lasted about a week. I returned to my car in a parking lot and unlocked it to see the lights flashing fast for 8 seconds (the manual says this happens when the alarm has been tripped). After less than a mile of driving, the "BONNET OPEN" message appeared. That went away soon enough.

It appears that the micro-switch inside the sensor might actually be faulty, resulting in intermittent failures. I've ordered a replacement sensor from an online shop. In the mean time, I've replaced my short circuit kludge.

UPDATE: Here are links to my others posts on this topic...

LR3 Hood Sensor  with actually useful photos

New links to replacement switches


Anonymous said...

how did you short out the hood sensor. I unplugged mine but am uncertain what to do. Thanks!

Michael said...

I used a short (0.75 inch long) piece of stranded insulated wire. I stripped both ends, then twisted the stranded ends a bit. Then shaped it into a "U" and jammed it into the connector. The stranded ends smush up against the contacts and work well. Then I taped it up with electrical tape. Eventually, I made more permanent repairs: see here.

I hope that helps.

Steve Shih said...

What would happen if I just left it unplugged? Will it damage anything?

Michael said...

Steve: It shouldn't damage anything. However, it's my understanding that the circuit needs to be completed to signal that the hood is closed. When I did my short circuit temporary fix described here, I taped up the end (to help keep the wire I had inserted from falling out) and left it hanging.