How To: Add shock sensor to factory alarm

[Carlos.33193]

I searched and was not able to find the information I needed to add a shock sensor to the factory alarm on my 2020 1500 Limited. If your truck horn/alarm goes off when one of the doors is opened then you can use this method. If you have a small red flashing light on your cluster gauge a few seconds after locking your doors then you should have the factory alarm enabled.

Materials:

• Fabric tape
• Micro2 Fuse tap x2
• 1N4001 Diode x2
• Shock Sensor DEI 504D or other
• NC SPST relay or SPDT relay
• Optional-Recommended: Toggle switch

You can use any shock sensor you want that outputs a - GND when triggered, I used the DEI 504D because it's what I had. This one has dual zone (warn and trigger), make sure the harness doesn't have both outputs tied together, in my case it was and it just has a wire loop that you cut. You can use a Single Pole Single Throw relay that is normally closed, or you can use a Single Pole Double Throw relay and use the NC contacts. I used a DEI 8616 mini relay (again, what I had) you can use any relay you want.

• DEI 8616 relay RED wire to Micro2 Fuse tap on F49.
• DEI 8616 relay BLACK wire and DEI 504D BLACK wire to spade or ring terminal to a ground lug. (Optional toggle switch in between if you want option to disable shock sensor)
• DEI 8616 relay YELLOW wire to Micro2 Fuse tap on F33.
• DEI 8616 relay ORANGE wire to RED wire on DEI 504D shock sensor.
• DEI 504D shock sensor BLUE wire to Diode (1N4001 or similar) to PURPLE/GREY-BLUISH driver trigger wire on driver’s side kick panel (band towards shock sensor).
• Diode (1N4001 or similar) across DEI 8616 relay RED and BLACK wire (band towards +).

Remove the lower left kick panel on the driver side, cut back the fabric tape that's covering the large bundle of wires and this is where the PURPLE wire, with a grey-bluish tracer line is located, this is the trigger wire for the driver's door. Carefully trim the insulation on this wire and check that you have the right wire by placing a small jumper wire to a nearby ground post, you should see your cluster gauge driver's door open light come on.

Make all the connections as per the schematic above (F33 fuse for constant 12v and F49 for accessory 12v can be used), mount the shock sensor under your dash and check for functionality, adjust the sensitivity as needed so you don't have false alarms (in my case the electric side steps were triggering it when they would try to fold in, so I kept lowering it until they didn't trigger it anymore.). Optionally you can mount a toggle switch somewhere as per the schematic incase you want to disable the shock sensor, maybe during a storm, or valet etc.

 

[l2iceman]

Bringing this thread back. I'm looking to install this in my truck. I have all of the parts as I had planned to do this for another vehicle.

Qq, if I were to open and close the tailgate before unlocking the doors, I believe this "shock" would set off the alarm. Do you know any way around this? I was thinking perhaps a relay that gets a signal when tailgate is open/ajar, and relay would connect/disconnect the ground. Not perfect, as leaving the tailgate effectively disables the shock sensor, but I wouldn't leave my tailgate open over night or for long periods of time.

I'd need to see which wire to tap into for that tailgate signal, or install a pressure switch.

 

[l2iceman]

Ok installed it today. I mounted it with zip ties onto the left metal bracket under the steering column (left to the fuse box), works nicely.

As mentioned above, opening/closing the tailgate sets it off as the alarm doesn't disable when opening it. I need to research some more to see if there's a "tailgate-open" signal I can tap into.

 

[Carlos.33193]

Ok installed it today. I mounted it with zip ties onto the left metal bracket under the steering column (left to the fuse box), works nicely.

As mentioned above, opening/closing the tailgate sets it off as the alarm doesn't disable when opening it. I need to research some more to see if there's a "tailgate-open" signal I can tap into.

I had this same issue, i just got used to using the fob to unlock (disarming) the truck before slamming my tailgate. I'm sure we can find that wire somewhere, but I didn't feel like adding anymore complexity to this project.

 

[jimothy]

Ok installed it today. I mounted it with zip ties onto the left metal bracket under the steering column (left to the fuse box), works nicely.

As mentioned above, opening/closing the tailgate sets it off as the alarm doesn't disable when opening it. I need to research some more to see if there's a "tailgate-open" signal I can tap into.

Just in case anyone else was thinking, like I did, "Wait a minute, don't all 5th Gens have a locking tailgate? Wouldn't you need to unlock the truck to open the tailgate?"

Yes to the first, no to the second: At least if you have proximity unlock, you can walk up to the tailgate with key in hand or pocket, and manually open the tailgate via the handle, without unlocking the cab doors.

Subconsciously, I knew that and I've done that a million times. I'm posting my thought process not because I was right, but because I was wrong, and I love embarrassing myself in front of you fine people. Or just to spare anyone else who also had this misguided thought in their noggin.

 

[l2iceman]

Yepp, I knew this going in that I'd have to unlock the doors before opening the tailgate, otherwise the vibration sets off the alarm lol

Thanks for your guide above, it was super helpful, including the diagram with diodes.

I'll adjust to unlocking doors/disabking alarm before opening the tailgate until I figure what to do with it.

If I can't find a factory wire to tap into, I'm thinking to use a pressure switch, could use it as the ground for the relay, so when tailgate is closed, the shock sensor is grounded, and when it's open, connection is broken, disabling the sensor.

 

[l2iceman]

Where did you mount the sensor? My alarm just went off with my neighbour parking and closing his door, so I switched it off for the night, and will turn down sensitivity tomorrow.

I'm thinking of moving it to the metal bracket on the right side of the fuse box, as it's more central. I stuck to the left side bracket initially as the trigger wire wouldn't reach, so I'll have to extend it tomorrow.

Also, where do you have the sensitivity set? Just curious. The dial doesn't have a alot of adjustment, like it can be turned clockwise to 3 o clock, or counter clockwise to 9 o clock, I currently have it set in the middle at 12 o clock.

 

[Carlos.33193]

I have mine set to around half. I mounted it to the big wire harness under the steering column.

 

[l2iceman]

I have mine set to around half. I mounted it to the big wire harness under the steering column.

Thanks! I did more research and moved OTT o thr big wire harness as well, mine is adjusted to about half as well and it seems to work perfectly now.

Only issue, the alarm itself doesn't seem to arm every time I lock the door. I've noticed the red dot on my gauge, I know the factory alarm is arming when I lock and see it flash quickly for however long (10 seconds?). But it doesn't always do this, I'm going to do some scenario testing to see if I can figure out the cause.

Such as, do I need to press lock twice (truck horn sounds off) to arm? Or does the shock sensor sense a shock and sends a signal at the same time I lock or during arming (coincidentally), thereby disarming bc it thinks a door opened?