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Old 03-09-2011, 03:41 PM
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Alarm goes off randomly, how do I disconnect the hood latch switch

Hi,

I've read about similar problems with the factory car alarm going off and I've located the problem to be my hood latch. People keep posting that you can disconnect the latch and put a jumper in the connector to solve the problem. My question is this...do I need to remove the hood latch (undo the 3 bolts) to disconnect the switch? I can't really see the harness and I'm afraid that if I remove the latch I'll have to fuss about getting it adjusted just right when I put it back on. Where is the connector? First time posting so any help is appreciated.
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Old 03-09-2011, 08:42 PM
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there is no hood switch for the factory alarm. the only thing that sets it off is the doors.
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Old 03-09-2011, 09:15 PM
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Yes there is. That's how you hook up shock sensors to the stock alarm. You wire them into the hood switch wire at the drivers side fuse panel. There's a trunk switch as well.
From the 03 service manual, there should be a connector at the back of the hood latch near the AC condensor. 2 wire plug. Jump the connector going to the car's wire harness.

Replacement of the hood latch should fix it though. Use a grease pencil or sharpie to outline the bolts & then use that when mounting the new one. Should line up perfect. It's a $51 part online.

Last edited by fuzzy02CLS; 03-09-2011 at 09:18 PM.
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Old 03-09-2011, 09:20 PM
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Originally Posted by fuzzy02CLS View Post
Yes there is. That's how you hook up shock sensors to the stock alarm. You wire them into the hood switch wire at the drivers side fuse panel. There's a trunk switch as well.
From the 03 service manual, there should be a connector at the back of the hood latch near the AC condensor. 2 wire plug. Jump the connector going to the car's wire harness.
but also the alarm will not arm if the hood is not fully closed (not just the safety latch)



anyways OP, there is a reason for that wiring to be hard to find, since it is part of the security system afterall, they do not want you to be able to find it easily (but iirc it runs on the underside of the radiator support, alongside the hood release cable)
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Old 03-09-2011, 10:16 PM
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My bad, I don't remember there being one when I took my latch off to adjust.. I'll have to look again..
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Old 03-09-2011, 11:11 PM
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Thanks for the input guys.....I thought it might be hidden on the underside of the radiator support. It looks like there might be some x-mas tree clips holding the harness in place. Can I get to the connector without removing the hood latch? Also, I keep hearing people suggest jumping the harness which would disable the alarm (I'm guessing) since the circuit will think the hood is open. What if I just disconnect the connector......won't the alarm continue to work, since the circuit will think the hood is always closed? Is my thinking correct?
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Old 03-10-2011, 01:27 PM
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Originally Posted by chicagocls View Post
Thanks for the input guys.....I thought it might be hidden on the underside of the radiator support. It looks like there might be some x-mas tree clips holding the harness in place. Can I get to the connector without removing the hood latch? Also, I keep hearing people suggest jumping the harness which would disable the alarm (I'm guessing) since the circuit will think the hood is open. What if I just disconnect the connector......won't the alarm continue to work, since the circuit will think the hood is always closed? Is my thinking correct?
probably have to at least remove the grill though (or at least the grill plastic piece, that goes between the headlights)



and your thinking, not quite correct, but close, when the latch/hood is closed, the switch is also closed, which means if you jumper the connector, it will think the hood is always closed


but personally i don't see why you don't fix it correctly, the battery is under the hood, which means the power supply for the alarm can easily be disconnected without it ever going off, because the hood is not activated anymore
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Old 03-10-2011, 03:29 PM
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OK, so jumping the connector makes the circuit think the hood is always closed. In that case my alarm should still work just fine.

I've already taken the plastic cover off (takes only 2 mins)......I'm gonna push down on some of those clips I see on the radiator support to see if I can get my hands on the connector to unplug it.
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Old 03-10-2011, 03:34 PM
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Maybe it is poltergeist?
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Old 03-10-2011, 04:16 PM
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Originally Posted by friesm2000 View Post
but personally i don't see why you don't fix it correctly, the battery is under the hood, which means the power supply for the alarm can easily be disconnected without it ever going off, because the hood is not activated anymore


A new latch is $50 online. PN 74120-S3M-A01
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Old 03-10-2011, 05:49 PM
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Originally Posted by chicagocls View Post
OK, so jumping the connector makes the circuit think the hood is always closed. In that case my alarm should still work just fine.

I've already taken the plastic cover off (takes only 2 mins)......I'm gonna push down on some of those clips I see on the radiator support to see if I can get my hands on the connector to unplug it.




and normally the connector/pigtail is within a couple of inches of the actual part, so it should not be TOO far away, but as others have said, it may still be further up then normally
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Old 03-10-2011, 06:46 PM
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OK guys, so I just disconnected the connector and the alarm works just fine. Problem solved! No need for a jumper wire....that would just disable the alarm. Thanks for the help.
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Old 08-11-2011, 08:45 PM
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Were you also having issues with the car unlocking by itself? I have already removed the grime from my hood latch and tested it for voltage and everything appeared to be good, but I'm still having this issues WITH my doors unlocking on their own too, so just curious. My next move would be to remove the hood sensor completely but I don't want to if it's going to be a complete waste of my time. Thanks!
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Old 08-12-2011, 11:08 PM
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Originally Posted by chicagocls View Post
OK guys, so I just disconnected the connector and the alarm works just fine. Problem solved! No need for a jumper wire....that would just disable the alarm. Thanks for the help.
I think my switch is confused. When I leave the hood open, it thinks its closed, vise versa. I am going to take apart the plastic pieces as well and see if I can disconnect mine... Anyone have any special instructions?

TSX not TL, but same issue I believe.
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Old 08-13-2011, 02:18 PM
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Update: Last night my car alarm kept going off. I decided to investigate further. I locked my car twice, no horn honk=alarm not activated. Waited for a couple of minutes. Sure enough, the light in my dash suddenly starts flashing red - alarm is now active - more than 5 minutes after I locked the car. It stays like that for about 5 more minutes, then the alarm goes off. So, in the span of 10 minutes or so, my car thought the hood was opened when I locked it, then closed, then open again.

I popped the hood, then locked the car. I got the horn honk - alarm activated. I then close the hood, with the alarm activated. Alarm does not trigger - but it stays activated. Since then, I've had it sitting outside, and every time I lock the car it arms the alarm - hood latch doesn't seem to be the issue anymore.

So - this leads me to believe one thing... somehow I locked my car months ago with the hood open, it got confused, and lost its reference point. By popping the hood and then locking it again, then closing the hood, it must have reset the sensor? Is it possible that Honda Engineers did not think that anyone would try to lock the car with the hood open, so they didn't design the sensor so it could distinguish between the two?

Anyway, sorry for the long post - but anyone having this issue should at least try it.
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Old 10-06-2011, 01:46 AM
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Originally Posted by Tangoman View Post
Update: Last night my car alarm kept going off. I decided to investigate further. I locked my car twice, no horn honk=alarm not activated. Waited for a couple of minutes. Sure enough, the light in my dash suddenly starts flashing red - alarm is now active - more than 5 minutes after I locked the car. It stays like that for about 5 more minutes, then the alarm goes off. So, in the span of 10 minutes or so, my car thought the hood was opened when I locked it, then closed, then open again.

I popped the hood, then locked the car. I got the horn honk - alarm activated. I then close the hood, with the alarm activated. Alarm does not trigger - but it stays activated. Since then, I've had it sitting outside, and every time I lock the car it arms the alarm - hood latch doesn't seem to be the issue anymore.

So - this leads me to believe one thing... somehow I locked my car months ago with the hood open, it got confused, and lost its reference point. By popping the hood and then locking it again, then closing the hood, it must have reset the sensor? Is it possible that Honda Engineers did not think that anyone would try to lock the car with the hood open, so they didn't design the sensor so it could distinguish between the two?

Anyway, sorry for the long post - but anyone having this issue should at least try it.

This is quite the theory you have going on here, and the conclusion would definitely interest me.

For the past few weeks I've been hearing a mysterious factory alarm (horn honking) going off in my neighborhood. It sounds an awful lot like *my* 03 CL-S... I'm trying to catch it in the act, but it does happen quite randomly and usually for some odd reason in the very late hours. I believe that my Clifford Aftermarket alarm is triggering the factory alarm some how. Interestingly, I thought I had this problem during last years winter too, and in my mind I honestly cannot come up with a plausible explanation as to why cold would trigger this behavior. SO, It is either another car, or the very cold weather that is causing this behavior, because during all of this summer I didn't once hear a single car horn honking outside.

Admittedly, It could just be some other car in my neighborhood (as there obviously are plenty of Honda's around, someone just moved in, etc.).

I do know that with aftermarket alarms there is a factory disarm wire that needs to be connected. This wire sends a pulse (from the Aftermarket Alarm) which tricks the factory alarm into disabling itself, emulating as if you had unlocked via the (factory alarm) fob. I believe using the drivers side door lock with the key also disarms the factory alarm.

I am not exactly sure what causes this factory alarm to go off under an actual theft scenario, I believe it is activated if you open the door from the inside of the car (while the system is locked and activated [without using the driver door key mechanism]) or insert the key in the ignition and try to start the car without first disarming. I was not aware that the hood or the trunk had any involvement, although the hood at least would make sense.

I had a hard time understanding the actual steps you took, so could you give us a step by step on how to reproduce it (cause it first, and then fix it)?
I believe your theory involves first someone accidentally arming (locking) the car with the hood open correct? ( I thought this wasn't possible, based on what some one else commented earlier in this same thread).
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Old 10-06-2011, 01:56 AM
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Old 10-06-2011, 08:02 AM
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I popped the hood, then locked the car. I got the horn honk - alarm activated
The pin switch or alarm is malfunctioning,. The alarm will not arm if the trunk, hood or door are open. Since yours seems to be hood related I'd say the hood switch had a problem.
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Old 10-06-2011, 03:33 PM
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Originally Posted by fuzzy02CLS View Post
The alarm will not arm if the trunk, hood or door are open.
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Old 10-07-2011, 05:17 AM
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Yes, figured it out. The hood switch is bad - it changes state constantly based on temperature, humidity, etc (typical of faulty electronics). Anyway, I took off the cover right in front of the radiator under the hood and unplugged that thing.

Because it only measures a state change, if you unplug it it will still arm and disarm just fine. Only difference is, someone can pop your hood and disable your alarm without it going off. I park in my garage every night and park at work during the day, no reason why I am worried about someone doing that. Maybe if I ever sell the car I'll spend the money and actually replace the switch.
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Old 01-27-2012, 10:19 AM
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Damn Hood Latch!

Originally Posted by Tangoman View Post
Yes, figured it out. The hood switch is bad - it changes state constantly based on temperature, humidity, etc (typical of faulty electronics). Anyway, I took off the cover right in front of the radiator under the hood and unplugged that thing.

Because it only measures a state change, if you unplug it it will still arm and disarm just fine. Only difference is, someone can pop your hood and disable your alarm without it going off. I park in my garage every night and park at work during the day, no reason why I am worried about someone doing that. Maybe if I ever sell the car I'll spend the money and actually replace the switch.
So I'm just running in to this issue now (2000 TL, 175K) and my neighbors are leaving notes on my car! Tangoman, any issues after just unplugging the wire running in to the latch switch? Seems like the easiest fix since I really have no need for the alarm.
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Old 01-28-2012, 09:50 PM
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Nope, no complications. Works great now that the hood sensor is unplugged.
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Old 01-29-2012, 07:38 AM
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my moms alarm was going nutz last week in the cold. I just opened the hood and slammed it back down and that set everything back in place and it's been fine since.

musta been frozen open or something i dunno how they really function, but i do know slammed the hood down may straighten that bad boy out
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Old 02-03-2012, 06:23 PM
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Yes, that is how I fixed mine for a bit, but eventually it just went bad. It might happen again, and you might just have to unplug it.
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Old 09-28-2012, 07:42 AM
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perhaps this is the reason for what happened to me last night...

get home from work just like normal...a lot of humidity after raining sporadically all day...back into garage where it's also humid...about 20 minutes later alarm goes off...thinking someone's trying to steal the car, i'm puzzled to see nothing looking out of the ordinary...so i re-lock the car and immediately notice NO FLASHING PARKING LIGHTS or BEEP when you lock a 2nd time, yet when i unlock the car, flashing lights...wound up opening doors, trunk, and hood to disconnect the battery...now everything seems fine, and she was quiet all night into this morning when i went to work, parking lights and beeping when i lock just like normal...but more rain today, and the car's sitting outside all day, so fingers crossed she stays quiet...how much is a replacement hood switch? or do you have to replace the entire latch in which case you're in the $50 territory?
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Old 05-02-2015, 09:44 PM
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Smile

Originally Posted by Tangoman View Post
Update: Last night my car alarm kept going off. I decided to investigate further. I locked my car twice, no horn honk=alarm not activated. Waited for a couple of minutes. Sure enough, the light in my dash suddenly starts flashing red - alarm is now active - more than 5 minutes after I locked the car. It stays like that for about 5 more minutes, then the alarm goes off. So, in the span of 10 minutes or so, my car thought the hood was opened when I locked it, then closed, then open again.

I popped the hood, then locked the car. I got the horn honk - alarm activated. I then close the hood, with the alarm activated. Alarm does not trigger - but it stays activated. Since then, I've had it sitting outside, and every time I lock the car it arms the alarm - hood latch doesn't seem to be the issue anymore.

So - this leads me to believe one thing... somehow I locked my car months ago with the hood open, it got confused, and lost its reference point. By popping the hood and then locking it again, then closing the hood, it must have reset the sensor? Is it possible that Honda Engineers did not think that anyone would try to lock the car with the hood open, so they didn't design the sensor so it could distinguish between the two?

Anyway, sorry for the long post - but anyone having this issue should at least try it.

This worked for me!

I opened the hood - set the alarm - closed the hood - unarmed the alarm.

I now am able to set my alarm and get the audible beep.
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Old 05-03-2015, 06:40 AM
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Originally Posted by BobbyG207 View Post
This worked for me!

I opened the hood - set the alarm - closed the hood - unarmed the alarm.

I now am able to set my alarm and get the audible beep.
Good luck! My hood sensor itself started to go haywire, it kept setting the alarm off. Works great now!
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Old 05-04-2015, 03:26 AM
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if your battery voltage drops it can trigger the alarm... It happened to me as my car is in storage and someone accidently disconnected the battery charger. Once I charged up my battery a bit the alarm started to act normally and no problems since then.
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Old 05-11-2015, 02:10 PM
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Originally Posted by Tangoman View Post
So - this leads me to believe one thing... somehow I locked my car months ago with the hood open, it got confused, and lost its reference point. By popping the hood and then locking it again, then closing the hood, it must have reset the sensor? Is it possible that Honda Engineers did not think that anyone would try to lock the car with the hood open, so they didn't design the sensor so it could distinguish between the two?

Originally Posted by BobbyG207 View Post
This worked for me!

I opened the hood - set the alarm - closed the hood - unarmed the alarm.

I now am able to set my alarm and get the audible beep.

This explanation doesn't seem plausible. There's no "state" maintained. The hood switch either provides continuity or not.

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Old 05-13-2015, 06:41 AM
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Originally Posted by lcstyle View Post
This explanation doesn't seem plausible. There's no "state" maintained. The hood switch either provides continuity or not.

It is true however that if your hood switch is acting up and it keeps thinking hood is open when it is actually closed, you can't set your alarm - but if you open that hood, it cycles the switch and it gets back on track. Then you can set your alarm and hope that when you close your hood again it doesn't trigger. For me, that worked for quite a while before the switch gave out completely. Then I just unplugged it.
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Old 05-18-2015, 09:31 AM
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Originally Posted by Tangoman View Post
It is true however that if your hood switch is acting up and it keeps thinking hood is open when it is actually closed, you can't set your alarm - but if you open that hood, it cycles the switch and it gets back on track. Then you can set your alarm and hope that when you close your hood again it doesn't trigger. For me, that worked for quite a while before the switch gave out completely. Then I just unplugged it.
Well, you are absolutely right. I have to sort of eat my shorts here. Recently my OEM alarm started going off again (horn honking randomly). I have an aftermarket alarm clifford which I installed myself, and so understand how the remote start works. There's a specific wire that sends an unlock signal to the OEM alarm that signals "disarm". It's obviously meant to work in conjunction with the factory alarm.

Well I went out there the other day to try to understand why it was happening, and happened to notice that when I hit the lock on my aftermarket alarm controller, the led indicator in the drivers door lock was not turning on! I immediately remembered this thread. I went ahead and popped the hood open, then hit the lock button, voila! the OEM alarm led started to blink indicating it was now active. After which I unlocked, closed the hood, and then hit the lock button again. Now the led comes on, indicating the oem alarm is activating.

It's a really weird problem / behavior. The only thing I can think of to explain this, is that perhaps the OEM alarm is measuring resistance versus just plain on/off continuity. And performing the above trick resets the resistance level "memory" it is using. I can't think that anything otherwise is happening because, if it were just the hood switch needing to be moved around a bit, well that should happen every time you open/close the hood.

Well glad we could get a confirmation for the fix. No more random OEM alarm horn honking!
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Old 05-24-2015, 10:24 PM
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nope..
now the oem alarm activates, red blinky led. but still goes off randomly. I'm going to pull the hood latch switch and test it.

I found the following troubleshooting doc:
dubdubdubacuraworlddotcom/forums/attachments/f49/28297d1307375375-alarm-keeps-going-off-cl9799s23136a.pdf

dubdubdubjustanswerdotcom/acura/641us-2000-tl-factory-alarm-just-goes-off-went-off-last-night-rain-storm.html
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Old 05-25-2015, 10:21 AM
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Originally Posted by lcstyle View Post
nope..
now the oem alarm activates, red blinky led. but still goes off randomly. I'm going to pull the hood latch switch and test it.

I found the following troubleshooting doc:
dubdubdubacuraworlddotcom/forums/attachments/f49/28297d1307375375-alarm-keeps-going-off-cl9799s23136a.pdf

dubdubdubjustanswerdotcom/acura/641us-2000-tl-factory-alarm-just-goes-off-went-off-last-night-rain-storm.html
Yea it's definitely just a simple switch but it is affected by rain I also found out.
Unplugging it in the best thing to do, that is how I fixed it.
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Old 05-25-2015, 02:24 PM
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Originally Posted by Tangoman View Post
Yea it's definitely just a simple switch but it is affected by rain I also found out.
Unplugging it in the best thing to do, that is how I fixed it.
Thanks. I spent all day outside in the car troubleshooting.

In the end I found it was the hood pin switch. I pulled the hood latch assembly out, then began testing by using a multimeter in "continuity tone" mode. I clipped my leads onto the pins in the connector, and then began actuating the lever. I could not get any continuity. The switch is supposed to be NORMALLY CLOSED when the lever is not actuated. I drilled the rivet and removed the switch.

I found it is a Matsushita AB J 39008 0.1A 125VAC 2UT

It's a SPST "simulated roller" Long Leaf Lever Action Normally Closed Switch. It doesn't appear to be IP67 rated to say the least, it was full of gunk.

I discovered that it was internally shorted. I could not find a direct replacement part which matches the dimensions exactly.

I've ordered a replacement part SPST-NC D2FW-G082M from mouser.

SPST-NC D2FW-G082M Watertight Snap Action Switch For Use In Automotive and Industrial Vehicles
• Conforms to IP67
• Single-point mounting with an M4 screw
• Incorporates a fixed leaf lever for tough environments
• Lead wires have solderless connections to suit environmental concerns
• Wide operating-temperature range of -40C to 85C

mouserdotcom/ds/2/307/D2FW-G_0607-1828.pdf

Right now I've got no hood pin switch (open circuit) which is the state that the switch would normally be when the hood is closed (open). I'll have to wait a few days to make sure nothing else is triggering the factory alarm. Also please note I do not yet have the part so I am not sure how well it will work in this particular application, or even if it will mount correctly.
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Old 05-25-2015, 02:43 PM
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Old 05-28-2015, 06:34 PM
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great success!

I was able to fit the new hood pin switch into the hood latch assembly.

It requires 2 modifications, the first, is that one of the plastic tangs on the side had to be cut off, this particular switch is wider than the original one. No big deal, as you only need one side. The other modification is to the remaining plastic tang on the switch's body, you have to slightly trim the outside diameter for it to fit into the latch assemblies existing hole, like the original switch's.

There was a slight bending of the new switch's "simulated roller lever" to a more acute angle, to make sure that the switch would positively engage with the hood mechanism in the closed position, as it's lever isn't as long as the original's.

Last but not least, make sure you give the very edge of the lever a downward roll at the end, to ensure that it never catches it's edge on the hood latch's component that interacts with it. I noticed due to my bending it was catching on the lever's edge and i created this bend to ensure it would roll.

Well that's about it, obviously no use of a rivet is necessary, as the switch is slightly longer and the rivet hole wouldn't line up anyways. I used the tang and quick set jbweld to keep it in positions. I made sure to clean the mounting surfaces as best I could to remove grease and grime, and then used brake cleaner. You can't see the interior mounting surface, but I did the best I could.

Well that's it. Hope it helps someone.

P.S. If you have an aftermarket alarm with a hood pin switch, you don't need the oem keyless entry's hood pin switch. One should suffice, however I do like to keep all stock functionality in the eventuality that one day the Aftermarket alarm goes away.
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Old 08-04-2016, 11:54 PM
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Watch this you tube
I bought the replacement switch from MOUSER by searching the part number in google.
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Old 01-21-2017, 04:24 PM
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Alarm keeps going off - hood switch

My 2010 MDX had the same problem. The alarm would randomly go off. I traced the problem to the hood switch. Contrary to what I have read on most posts the hood switch functions as follows (at least for the 2010 MDX): When the hood is open the switch level is pressed and the circuit contacts close resulting in alarm condition. When the hood is closed the switch lever is not pressed and the switch contacts are open circuit. Therefore, if you suspect the hood switch as being the problem, simply disconnect/unplug it and the alarm system will think the hood is closed. If you don't get any alarm, then you can replace the switch or just leave the connector unplugged. If you want more in depth detail read on...The switch is located as part of the hood latch assembly. If you look behind the hood latch (between the engine and the radiator) you will see a small grey two wire connector. Simply unplug it and the alarm will think the hood is closed. I went into further detail and removed the black plastic rad cover which is held on with black plastic clips. Next remove the three 10 mm bolts that hold on the hood latch assembly. Its a good idea to mark the position of the hood latch before removing it so that you can easily realign it later. Once removed (or you don't need to remove it for testing) you can easily place an ohm meter or continuity tester on the 2 switch connector leads. You should measure less than 10 ohms with the hood open, and infinity or very high resistance with the switch pressed or the hood closed. When I tested my switch I found 100 to 20000 ohms all the time and it would jump around. A good switch should not do this. Anyway, if you want to replace the switch you need to drill out the rivet that holds it in place (its very easy because its aluminium). I did this. I then reinstalled everything back except the switch. I now need to find a replacement switch which I doubt Acura sells as a separate part. If anyone knows where to find a replacement switch let me know. The whole job took about 60 minutes to complete. Thanks for the former posts and good luck.
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