OBD port disable switch

[Mooseman]

With the increase in vehicle thefts in my area, I want to do something that would prevent the reprogramming of keys via the OBD port. Since I put my fobs in a signal proof faraday box to prevent using a signal booster/repeater, the only other way to start my 2021 Sierra would be to program a new key fob directly. Saw some ideas for fake/dead ports or a lock box on top of it. I just want something simple. What I was thinking was a double pole/double throw switch hidden somewhere to kill just the data lines to the port. I thought of killing just the power to it but that won't work if their programmer has its own power source. Since it's a newer vehicle, I would have to cut both the high and low speed data lines.

@TJBaker57 , do you think this would work? When the switch is flipped back on, will data work properly? My gut says it would unless I need some special switch or something.

 

[TJBaker57]

I am afraid I don't know squat about vehicles younger than say 15 years old!!

That said, I can't imagine that disconnecting network wires like those to the DLC that don't actually terminate in a module could affect anything at all either while disconnected or when reconnected. As long as they never ground out or touch each other since the network is still viable even when the ignition is off.

However, disconnecting the DLC may not stop the educated bad guy. I suspect there are other places the same wires can be accessed. On my old Trailblazer I can pop the hood with a screwdriver and quickly access the single wire serial data and send a command to unlock the doors or whatever.

 

[cornchip]

I am afraid I don't know squat about vehicles younger than say 15 years old!!

That said, I can't imagine that disconnecting network wires like those to the DLC that don't actually terminate in a module could affect anything at all either while disconnected or when reconnected. As long as they never ground out or touch each other since the network is still viable even when the ignition is off.

However, disconnecting the DLC may not stop the educated bad guy. I suspect there are other places the same wires can be accessed. On my old Trailblazer I can pop the hood with a screwdriver and quickly access the single wire serial data and send a command to unlock the doors or whatever.

Exactly what happens with current Jeep Wranglers when owners relocate the OBD plug to stop new fob programming. Thieves have learned that the ODB cable has it's own plug behind the glove box and now go directly to that location. They learn fast.

 

[azswiss]

With the increase in vehicle thefts in my area, I want to do something that would prevent the reprogramming of keys via the OBD port.

@Mooseman, you could also move the real OBD port (say further up under the dash) and then place a dummy port in the official spot. Snip an OBD port along with a segment of wiring behind it (10"-12") out of a wreck at the pick-a-part. If you need access to the real port (e.g. registration inspection) you could temporarily restore it to its normal location.

 

[Mooseman]

However, disconnecting the DLC may not stop the educated bad guy

Educated? These mooks are just given the tools and told how to use them. I doubt the big boss (the educated one) would actually go out there himself. If they have to start opening hoods and poking around in wiring, it would take too long and increase the risk of getting caught.

What I have so far:
- driveway lit up like a football field from sundown to sunrise
- key fobs kept in a faraday box
- cameras

I just want to add one or two more layers to make it less palatable for a thief to even try to take my truck. Also looking at using a steering lock. Found out that the common Club ones can just be bent. One of these two I might go for.

https://www.amazon.ca/dp/B00M08XFMU/?tag=gmtnation-20

https://www.amazon.ca/dp/B09WDKDVZC/?tag=gmtnation-20

This guy had thieves try 9 times to steal his 2018 Grand Cherokee. Target hardening works.

An 'unstealable' car? How a Toronto man defeated car thieves 9 times

As a wave of car thefts sweeps over Ontario, one Toronto driver stands out as an exception.

toronto.ctvnews.ca

@Mooseman, you could also move the real OBD port (say further up under the dash) and then place a dummy port in the official spot. Snip an OBD port along with a segment of wiring behind it (10"-12") out of a wreck at the pick-a-part. If you need access to the real port (e.g. registration inspection) you could temporarily restore it to its normal location.

We don't have e-tests anymore so that's not an issue. I just thought something simple so that if a tech needs to use it, all I need to do is flip a switch or tell him where it is.

And of course there's the good old fashion kill switch. I'd probably wire it to the fuel pump so that it'll just crank and maybe just that will be enough to wake me or the dog up.

 

[Beacon]

the tevlaphee wheel lock looks nice, 130db is pretty damn loud too, almost painful to a thief who didn't have ear plugs

 

[azswiss]

What I was thinking was a double pole/double throw switch hidden somewhere to kill just the data lines to the port.

Rather than mess with the signal lines you could use the DPDT switch to disable the chassis & signal ground pins in the connector. No chassis ground would stop power and no signal ground would disrupt the two Can Bus signals.

 

[TJBaker57]

Long ago a mechanic friend said to me that rather than kill the fuel pump straight away use a timer that lets the pump run for a short time then kill it when the vehicle is likely moving down the road.

His thoughts were that it is less likely for some thief to fiddle around in the middle of the road trying to get it going again.

 

[NJTB]

Worked in dealerships in the 70's, 80's and a bit in the 90's. Literally 1 to 2 new cars and 1 or 2 customer cars were stolen in a month. Security cameras showed the thieves, police very seldom caught them.
Didn't matter if the cars had alarms or whatever, the only thing that would get the car back was Lojack.