Automobiles are made up of many systems: the starting system, the fuel system, the electrical system, the air conditioning system, the lighting system, and so on. In the past, these systems operated independent of each other. Today, they are integrated into the complete vehicle design to provide us with a more comfortable, safe, and secure vehicle. The down side of this is that adding certain accessories to the vehicle can have unwanted side effects and cost you a lot of money in repair bills. Lets look at the more popular accessories.

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One of the more popular options this past winter has been a remote starter. They sound wonderful! Just press a button and your vehicle will start, warm up, and have the windows clear of frost before you leave the house. Some even have an option that will start the vehicle automatically if the engine temperature drops below a programmed temperature for those times when you can’t plug it in. There are several manufacturers of these products, and they try to tailor the operation of their system to your vehicle, but it doesn’t always work!

The biggest problem with remote starters is they conflict with many of the factory anti-theft systems incorporated into new vehicles. Some vehicle anti-theft systems such as the General Motors Pass Key were relatively easy to install remote starters on. This system uses a special ignition key with one of fifteen different resistors mounted on it. When the key is placed in the ignition, the fuel injection computer is signaled that the correct key was in place and the fuel system was turned on. When a remote starter is installed on this system, a relay with the correct internal resistance is used to signal the computer to turn the fuel on.

Another GM system uses a timing signal from the rotation of the key assembly that is sent to the instrument panel. The instrument panel then determines if the correct key has been used and sends a digital “turn on” signal to the fuel injection computer. This digital signal can be different for each car so it is very difficult to install remote starters on this type of vehicle.

Other anti-theft systems use radio signals from a pellet placed in the ignition key. Many Ford and Nissan cars have this feature. When the ignition key is inside the vehicle, it sends its special revolving code signal to a receiver located in the dash. If no signal is received, the vehicle will not run.

Other manufacturers have used infrared light signals from a key fob transmitter to disarm vehicle security systems. If the security system is armed, the vehicle will not start, even with a remote starter system!

Another concern with these systems is their effect on vehicle driveability. The electrical connections of the remote starters are often connected into some computer controlled circuits. They can cause problems on these circuits even when the remote starter is not being used. Examples are engines stalling, not starting at some temperatures, hesitation when accelerating, and even the transmission not shifting (most automatic transmissions are computer controlled now)! Most manufacturer’s repair manuals now contain instructions to disconnect any electrical accessories connected to any computer controlled circuits before attempting to diagnose any driveability problems. This is not covered under warranty so there is a cost to the owner!

The keys to installing a good working system are the knowledge and skill of the installer, the reputation and after-sales service of the company that installs the unit, and the quality of the remote starter system itself. Some remote starter systems have had more development to enable them to work on today’s vehicles. Shop around for all of these before making a decision. Depending upon how new your vehicle is, this is one time when the cheapest price can cost you more in the long run.

Other electrical options such as telephones and stereos can also cause problems, but they don’t seem to be as bad because they are not usually connected into the vehicle’s computer system. Also, the manufacturers of these systems are usually larger companies with the resources to solve vehicle driveability problems caused by their systems. The most common problem with these systems is a poor or incorrect installation.

Any electrical accessory must have its battery power and ground connections isolated from the vehicle’s computer power and ground. If they are supplied from the same connection, then interference can be transmitted down the wires and your vehicle runs poorly. Be sure to run any antenna leads or speaker wires as far away from other wire harnesses as possible to reduce the chance of electromagnetic signals being introduced into computer wiring. If the wires must be near each other, place them so they cross at as large an angle as possible. This will help to reduce electromagnetic interference.

Again, the key to a good installation is the knowledge and skill of the installer and the reputation of the business doing the work.

Shop around before adding any electrical options to your vehicle. Ask other owners with the same make, model, and year of vehicle as you have. If they have problems with a certain manufacturer or installation shop, then don’t make the same mistake. Any good shop will stand behind their products and their installation. Just be sure to ask them if they will repair your vehicle if their accessory causes any driveability problem.

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