Adding Shock Sensors to the Factory Alarm by guitarplayer16

15 minute read

Adding Shock Sensors to the Factory Alarm 

Compliments of guitarplayer16 @ https://acurazine.com

4-28-2012

I've explored the topic of adding a shock sensor a few times when I bought the car but never found a good DIY on what to do.

So what's a shock sensor?
It's a sensor that detects a shock or impact.
When the shock or impact is detected, it sets off the factory alarm.

Our car doesn't have a warning siren so it doesn't "beep beep" when someone lightly hits your car.
It will just set off the alarm no matter how hard the impact.

You can change the sensitivity of the shock sensor.

Demo Video:

How does it work?

Well, as you know our TL comes with a factory alarm that goes off if the doors or trunk or hood is opened without the keyfob or keyhole.

When the sensor is wired, it means everything is in harmony, no disturbances.
When it detects a shock or impact, it sends a signal to the hood latch switch wire which tricks the alarm system thinking that the hood was popped open, therefore setting off the alarm.

Most of you are wondering, when you're in a mall or something and sets off your alarm but obviously you're oblivious to it as our oem keyfob doesn't alert us anything.
That's right, but if someone hits your car, they'll probably less likely "hit and run" because your car alarm is going off, and that will alert people nearby. That means that person who hit your car will think "damnit I'm caught and everybody is watching me".

If someone bangs your car by accident (with grocery bags or elbow), it'll set off the alarm and just really tell them to be more careful next time when they park next to a sexy car.

The beauty of this DIY is that you don't have to install a shock sensor, but you can install a glass sensor, proximity sensor, or tilt sensor to the factory alarm.
Or, you could install ALL 4 of those!

Now you know why to add shock sensors, lets get to it!

NOTE: I apologize in advance that the picture quality sucks!
The pictures I took were good, but they ended up being like 250kb each so I optimized them using a site and they turned out to be like 20KB each.
This means fast page loading, for the small price of quality! =)

Materials List:

1. Shock Sensor (DEI 504D).
Purchased from eBay for like $12.

2. 4 Butt connectors (18-22AWG)

3. 1 Splice Connector or T-Tap connector (18-22AWG)

4. Spool of 18 AWG wire.

5. Mini Add-A-Fuse (with 3A fuse)

6. 1 Ring Terminal

Steps:

There are 3 wires we have to wire up.
It's that easy to install a shock sensor.
Therefore I will divide this DIY into 3 sections for each wire.

Wire 1: Trigger Wire (Blue Wire)
Wire 2: Positive Wire (Red Wire)
Wire 3: Ground Wire (Black Wire)

1. Open up your DEI 504D bag, and you'll have a sensor and a harness.

2. Connect the end of the harness with the green wire looped into the blue wire's pin.

3. Go out to your car, and place the shock sensor and its harness in the driver seat.

4. Cut off the one end of the sensor harness.

Before:

We'll be wiring the blue wire first, which is the trigger wire.
This wire will go to the hood latch switch wire.

As always, UNPLUG YOUR NEGATIVE BATTERY TERMINAL BEFORE WIRING!

1. Grab your spool of wire, and feed the wire through the firewall (while your spool unravels itself).
You can do what I did which is poke a hole through the rubber seal with a bunch of wires (I already did this for my accord fog install).

You'll have to remove the lower dash panel at this point. (NOT the dash with the VSA, Mirror, etc. The one under it)
There's just one screw at the right and you just pull the lower dash panel down, starting from the back.

(Sorry for blurry picture, it looks like there's 4 wires but there's only 2)

OR you can use the hole in the firewall outlined in this DIY:
https://acurazine.com/forums/3g-tl-audio-bluetooth-electronics-navigation-94/diy-aftermarket-amp-install-speaker-install-audiocontrol-matrix-install-w-pics-580314/

2. Extend this wire (while your spool is unravelling itself from inside the cabin) all the way to the hood latch.

At this point, you could do what I did which was remove the front bumper to access the hood latch switch wires easier. I believe you can do this without removing the front bumper by jacking up your car and doing it from beneath.

Here's a GREAT video to show you how to remove the front bumper:

3. Pop the latch cover (just a few clips) and you'll see the hood latch switch connector.

4. Unplug that connector.

It has the green/black strip wire we need to tap into

5. As you can see, there's not much space to tap into. All you have to do is remove the electric tape around it and crack open the loom.

Much better:

6. Route your green wire into the latch cover and place it beside the latch switch connector, ready to tap.

Notice how I DIDN'T route the green wire around the cover, but through it?

7. Using your splice connector, tap the green wire into the green/black stripe wire.

8. Plug the connector back in.

We're done with the outside of the car.

Tidy up the wires, and run it along the side.

9. Back inside the cabin, you want to cut the spool of wire, now that you have your desired length from the cabin to the hood switch.

10. Strip the insulator on the wire from the hood latch switch and the blue wire from the sensor harness.

11. Take a butt connector and connect these two wires together.

The trigger wire is now wired and done with.

Stage 2: Wiring the Positive wire

1. Strip back the insulator on the red wire on the sensor harness.

2. Take your spool of wire and cut a wire about 1-2 feet.
Strip the insulator at both ends.
This extra wire is just for "slack".

3. Connect one end of this "slack" wire to the red wire on the sensor harness using a butt connector.

4. Now take your add-a-fuse, and add a 3A fuse to the slot B for the accessory.

5. Take the other end of the "slack" wire and connect it to the add-a-fuse wire using the butt connector already on the add-a-fuse.

6. Route the add-a-fuse through the top of the fuse box cover.

7. Remove the 20A fuse from the middle row second from the left. It's like the recline fuse which is constant 24/7.
Stick this 20A fuse into the add-a-fuse.

8. Now plug the add-a-fuse into the fuse you took the 20A fuse out of (middle row, second from the left).

(The second add-a-fuse is for my footwell LEDs)

All done wiring the positive wire!
Now onto the last wire: ground wire!

STAGE 3: Ground wire

1. Strip back the insulation on the black wire of the sensor harness

2. Know how we made a slack wire of about 1-2 feet for the positive wire?
Well, do the same with the negative wire and strip the insulator back on both ends!

3. Connect one end of the slack wire to the black wire using a butt connector.

4. Connect a ring terminal to the other end of the "slack wire".

5. Take this ring connector and bolt it to a ground bolt.
I used the ground bolt right under the steering wheel (I used the same for my accord fogs).

The bolt is a 10mm.

All done wiring the shock sensor!!!

At this point, go ahead and plug in the negative terminal on the battery.
Test it out!

Here's how:

Sit in your car.
Lock the doors using the remote and lock again to hear the beep.
Wait about 30 seconds.

Tap your foot on the ground (assuming the shock sensor is just sitting on the ground as I have not told you how to mount yet!!).

The red LED inside the sensor should light up telling you it detected a shock, and the alarm will go off.

Press unlock on your remote to stop the alarm.

If you have gotten this far, everything is pretty much done.
You just have to mount the sensor somewhere...

STAGE 4: Mounting

To be honest, this stage is pretty much up to you.

DEI recommends installers to zip tie the sensor to a large bunch of wires in a central location.
Many installers say no to the zip tying it to wires, but instead to something solid and metal.

I mounted the sensor using zip ties to the metal support beam thing right above the gas pedal and to the right of the steering column.

On the side of the sensor is the sensitivity adjustment so make sure that's accessible.

Put everything back together and you're done.

************************************************** *
Alternate Trigger Wire Wiring
Source: anthracitecl

Thanks to our member anthracitecl, there is an alternate source for the trigger other than the hood latch.
This would mean there is no need to remove the bumper - and you save some extra wire too lol

Here are his instructions:

Hood latch switch wire(Green/black) comes out from relay control module(bottom of fuse box).The relay control module is part of underhood fuse&relay box. When you look at wire loom coming out from under the fuse box, there's Green/Black wire(There's only 1 Green/Blck wire and it changes to Yellow/Red to hood latch.). To reach that Green/black wire bottom of the fuse box,you have to unbolt 2 10mm bolts that hold fuse box. You might have to remove intake, but i didn't. I wired it up to that Green/black wire.
Here are some pics.

My little screw driver pointing out Green/black wire.

This pic is after i soldered wire(i used blue wire for extend) to green/black wire.

An example of the shock sensor (DEI 504D, same as mine) added to the factory alarm in action on a Corvette.