Diagnose Anti-Theft System

Engine Related Issues

By Rodney (Mechanics)

The purpose of the anti-theft system is to prevent car theft. Most anti-theft system that available on market is working good and reliable. However, when the anti-theft system act up, it can caused many issue and so annoying. Your car won’t start, or it can causing the engine to stall, or while you are driving the system can killing the ignition right away. And without apparent reason the alarm will go off, or when you don’t shut off after open the door with key the alarm also will go off.

The installation of anti-theft systems by factory usually more less issue and more reliable compared with the aftermarket anti-theft systems. Anti-theft system that installed by factory usually will integrated into powertrain control module (PCM) or body control module (BCM), so when someone starting the vehicle without key, the engine won’t start. The factory anti-theft system will make a flash the lights and also sound an audible alarm with horn or hidden second horn, if someone without key or keyless entry fob is not unlocking the door first when opening it. Aftermarket anti-theft system also have same thing like that, it’s also include remote disabling, remote starting capability and GPS to tracking the vehicle if it has been stolen.

The issue with installations aftermarket anti-theft products is depend on your installer. When the installers is a professional technicians and properly trained, the systems should work properly and shouldn’t have any problem. However, when the technicians install the anti-theft system by splicing to the wiring, then probably variety of potential problems will occurs. Tapping into the inappropriate power circuit could rob voltage out of a system, causing you have another problem unrelated with anti-theft system. We have heard of aftermarket systems placing engine misfire codes since it was cutting out the ignition to get a two or three while the car was being driven.

Durability and quality is another issue aftermarket anti-theft systems, in recent day so many electronics are made in China, and most of them use recycled components and chips, or they assembled the systems with low quality. As a result after the use of some time (1 or 2 years) the systems will causing an issue or completely fail. So, buy the anti-theft system with long time warranty is the smart solution, and someday in case the system fails, broken or have an issue, you can file a claim and hope the manufacturer is not bankrupt and still in business to honor the warranty.

Anti-Theft System Problem Diagnosis

In case the anti-theft or the safety light is flashing when you try to start your vehicle, and the engine doesn’t crank or doesn’t start, you’ve got an issue. The system might not be recognizing keyless entry signal or your key not readable, or there can be a fault at wiring, anti-theft module or keyless entry system.

If your vehicle has a key fob, the battery from the key or fob could possibly be dead, or there might be a fault at the key or fob processor that’s preventing the system read it. Might need to diagnose the system to ascertain what may be causing the issue.

Possibility To Cheat, Circumvent and Disable Anti-Theft System

When the anti-theft system is factory-installed, likely not. Remember, thwarting car theft is the purpose of designing an anti-theft system, if the system is easy to bypassed or disable, the car thief will be happy to do so. Many ways to deal with car theft systems, but most ways are too expensive and time consuming, or even for some people will find it too complicated to understand. Suppose there is an easy way, we will not tell you in this article. And if you ask us to write the secrets, it means we just give keys to everyone to steal your car.

If you have an aftermarket anti-theft system, also you’ve got directions that came with it or the setup manual, you disconnect the machine and then could find all of the areas where it’s spliced into the wiring. Or, you can take to the installer and ask to replace it with the new system or ask them to remove it.

Anti-Theft System Only Can Be Accessed by the Certified Repair Outlets or Car Dealers

Only new car dealer personnel who have access to the system for repair or diagnosis, this is one of the protective measures designed into the anti-theft system, and the scan tool that should be used for diagnosis and can access the system must be a factory scanner. So if your anti-theft system is factory installed and you have an issue with it, to diagnosis and repair it you need go to the dealer.

NOTE: To gain access to information on anti-theft services required locksmiths who have undergone screening and certification, and of course also meet the criteria for obtaining access to anti-theft system. Not many have signed up for this program because the cost is not cheap.

Factory Anti-Theft Systems

Some vehicle manufacturers use different types of anti-theft systems: General Motors has anti-theft system known as Content Theft Deterrent or CTD, when you open the door without key then the system will sounds an alarm. But this system does not guarantee your car safe and prevents car thieves from driving your car away.

Factory anti-theft systems which disable the ignition, the fuel system or even the starter to stop your car from being stolen: GM’s VTD (Vehicle Theft Deterrent) or Pass-lock system, Ford’s with their PATS (Passive Anti-Theft System), and Chrysler’s has SKIS (Sentry Key Immobilizer System).

Ford Passive Anti-Theft System (PATS)
Ford Passive Anti-Theft System (PATS)

Most use an ignition key which included a transponder chip that is coded. The transponder receiver at the ignition switch will read the key. The signal from the key then routed via a body control module (BCM) or the anti-theft module into the engine computer, which receives either a “move” or no go” signal.

When you turn the key the engine won’t start because the computer would not turn the ignition on, starter or fuel system (depend how it configured) due the anti-theft system send no-go signal or no signal at all to PCM.

Security or anti-theft lights are your key point whether you are facing a problem with an anti-theft system or other problem (see Engine Won’t Start article). When you attempt to start the engine and the light continues to flash, you aren’t going to anywhere because the system is sending out a no-go signal. You need to towed your car to the dealer for diagnosis and repair.

Anti-Theft System Goes Wrong

When the faulty occurs with chip inside the key or it has been damaged, the anti-theft system will not recognizing your key. Or if the fault is happen with the receiver within the ignition switch, possibly your key will not recognizing by the systems. Sometimes signal interference occurs from another computer chip key in the same key ring, it caused the correct key signal receiver in the ignition switch become interrupted.

This happen on Chrysler owner who have two key (another Chrysler) on same key ring. Sometimes the key readable by the receiver as correct key and engine can be started. However sometimes it will be read as wrong key (although another key wasn’t in the ignition) and the engine won’t start. The worse can be happen the engine can suddenly stall, because the receiver will read another key and losing signal from correct key while you are driving. The solutions is DO NOT put the other key (two different Chrysler keys) in same ring.

When your car has a remote starter or key-less entry system, and the engine isn’t starting (anti-theft light flashing), then the battery within your entry key-less system fob could possibly be dead (or try changing the battery), then there can be a fault at the fob itself (if you have another one try to use it), or the signal does not reach the receiver. If the module is receiving a signal and processing it correctly then go to the dealer to fix it. Either, you need to replace the anti-theft module or the key-less entry receiver to fix the problem.

Anti-Theft System Reprogramming

To able the anti-theft system accept and identify the new keys or replacement module, it need to be reprogramming again when you have replace the module of anti-theft system, or when you lost your key or you have a bad key. On some car, like a Mercedes models, the ignition keys have been paired to the power-train control module (PCM). It’s means you’ve got to need to replace the power-train control module (PCM) since reprogramming isn’t possible when you lose your keys!

An authorized locksmith or a dealership technician the only can do reprogramming job done. The fee for this could be $75 to $150 depending upon how long the process takes. Some system relearning or reprogramming processes can take 20 minutes or even half hours to finish. Time-delays are built to prevent someone from using a factory scan tool and get codes from hacking on your anti-theft car system and reprogramming the keys.