In this article I’ll talk about piggy backing a Directed Electronics (DE) 507M tilt sensor to the stock Scion Security car alarm. This add-on was made popular by the Prius community because of catalytic converter thefts. They wired up a 507M to their stock car alarm as an added theft deterrent.
I will describe how I’ve customized it for the 1st Gen Scion tC.
Why did I install this?
I installed this module back in August 2023 as an added theft deterrent to my newly installed ESR CR5 rims. Essentially if someone jacks up the car, the alarm will go off. This can also be used to protect other parts like exhaust systems, intercoolers, ground kits, suspension, etc. Protect your investment!
It works. Let’s see it in action.
TLDR
If you want the meat and potatoes here’s my wiring diagram, I’ll talk about it more below.
This install only works with OEM Scion security alarm
However you can apply these concepts to any car really.
1) You have the Scion security alarm panel with the LED and glass break sensor shown here:
2) Verify this by going to the Alarm security module behind the glove box and look for part number shown here: 08190-04810
If you have the dealer installed after market alarm that has a valet switch installed at the driver kick panel, this article DOES NOT apply to that alarm, but you are welcome to continue reading how I installed this and see if this info helps with your specific setup.
The Packaging
There’s two types of packaging for this module, Xpress Kit (OEM) or Retail blister packs
Blister pack
Wires
- RED 12V input power
- ORANGE input switched ground
- BLUE negative output to alarm
Here’s the wiring from the Prius community
This is the specific wiring diagram that got me to understand the install better. Thank you user MARK010101
Here’s the gist
- The 12v red wire is supposed to be constant power.
- The orange wire will be switched ground using a relay. Meaning it is grounded after the key is switched OFF, as in you’re exiting your car.
- The blue wire we will use to power a relay to trigger the alarm (send output to the door trigger wire), as displayed in the Prius diagram above
Scion specific install
The problem with 12v constant power is that technically the 507 tilt sensor will arm when you switch the key off, if you follow the DE or PRIUS instructions. We don’t want that, that will trigger false alarms.
For instance, you park your car and turn it off because you’re waiting to pick someone up. In the wiring above, the tilt sensor would be armed. I’ll find a 12volt power source that is HOT only after the car is armed. I’ll grab this from the car alarm module. More on that later.
I’ll also interrupt the 12v power mentioned above with a switch, so I can disable the tilt sensor if needed.
Bench test of relay for negative send trigger
Grab any available slot at fuse block
RED WIRE – 12V power source only AFTER the car alarm is armed
Here’s where my install is different from the rest. On the Scion tC car alarm module, I discovered a 12v power source that goes hot AFTER arming the car. I assume this is for other accessories/modules
My wiring diagram
Important Relays
Additional thought for consideration
I haven’t tested the tilt sensor in the following scenario:
You park your car, someone jacks up your car, the alarm goes off, you’re not around to disarm it. The car is left on bricks (or jacked up). I’m assuming the 507M resets it’s zero degree to the new angle it’s sitting at. Don’t know here.
Links to soldering tools and accessories
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Adjustable heat soldering tool kit complete with extra tips, solder, flux, etc. You can use this for the DIY Cluster LED swap too, very handy to have
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Butt connectors that melt solder to the connections, I really like these
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Heat gun with melting shield, great for melting the butt connectors above. You can get in tight spots without heating up neighboring parts
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Tube shrink wrap, I use this stuff all the time to cover up raw wire soldering and to water proof butt connectors
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Mini fuse taps, these come in handy if you want to piggy back off existing HOT or switched AC power from the fuse box near the driver kick panel.
