Skip the auto shop - Our mechanics make house calls

Q: Antitheft system causing car to not start

asked by on

The passive antitheft system is causing my car to not start.

A: Depending on where and how the security sys...

Depending on where and how the security system was installed, this can change the possibilities of various issues and fixes. An aftermarket system put in by a private party could have been installed in different ways that could cause issues with the starting system or other sources depending on what the power is being drawn from. As where an OEM security system that came with the vehicle will have wiring diagrams and more diagnostic specified information about where the problem is coming from. Also there is a possibility that the dealer installed an aftermarket security system which falls in the middle of the other two. Possibly because the dealer may have had the schematics for the installation or in some cases they may have not. The best plan of action would be to have a qualified technician like the ones here at YourMechanic, perform an electric diagnostic on the security system in order to map out how the siren was installed. If the system wasn’t installed properly the car might not start. In this situation it can only be started with the supplied key fob with an auto start. In some bad cases it’s possible for the vehicle to not shut off at all.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Car won't start but when attempting to start it makes a repetitive "pop" sound.

Hi there. What could be happening is the engine has either a large vacuum leak or the timing chain has skipped a tooth making a camshaft out of adjustment. First look all over the engine for any possible vacuum leaks,...

Q: How do I arm the immobilizer?

The immobilizer is a key security feature. The immobilizer is responsible for making sure that your vehicle can only be operated with an authorized key. The system cannot be armed or disarmed; it will automatically arm when you remove the...

Q: Short in turn signals

Hi. If the fuse is blowing, you have a short to ground. If the parking lights flash with the turn signals or the brakes, check all 4 bulbs. There are two filaments in your turn bulbs. When either burns out,...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...