Car likely has three different anti-theft systems installed

by Jim KerrBackyard Mechanic . Feb 17 2017

Question: I have a theft deterrent query. I have a 2001 Impala, which I bought second-hand. Everything I googled says Impalas have a Passlock system that works through the ignition switch but I also have a plastic red bullet-shaped fob on the key ring and I am wondering if I have two anti-theft systems (manufacturers and aftermarket).

There is a red blinking light just below the radio, which I am assuming is the “armed disarmed” indicator light as it usually goes off about five to 10 seconds after the key is turned to the on position. How do I determine what anti-theft system is in the car?

I am having issues with the anti-theft system, but first I need to figure out if I have one or two systems in the car. My insurance company often makes people put in a second anti-theft system. The problem that is occurring is the red blinking light is not always going out and I cannot start the car until it does. The security indicator on the cluster panel is NOT coming on. I am getting around the problem by pulling the BCM fuse and/or then doing a quick on/off turn of the key a number of times and then the red light stops blinking and I can start the car — a temporary solution at best. Please help.

— Darlene

Answer: There are probably three theft deterrent systems on your Impala. The radio theft deterrent has nothing to do with starting the car. The red blinking light is an aftermarket add on. The red fob with the keys is also not factory equipment, so I suspect you have an aftermarket immobilizer on the car. These are installed for a variety of reasons, including a few finance companies who can stop the engine if car payments are not made.

The factory anti-theft system works two ways but both use the security light on the dash. The Content Theft system helps protect vehicle contents and sets an alarm off if the vehicle is broken into. The Vehicle Theft system prevents the engine from starting if the ignition switch is broken. If these were not working, the yellow security light on the dash would be blinking when the car does not start. This needs to go to an electrical expert who can either disconnect the immobilizer or determine its make and install another unit.

Question: I have a 2010 Hyundai Accent that has very low mileage, 32,000 km. It has been misfiring for quite some time at idle and during acceleration mostly. The engine light is NOT on and I have had it to a garage anyway for a scan but it does not show anything. Have you any suggestions?

— Donna

Answer: The engine on board diagnostics monitor crankshaft acceleration and deceleration rates during each cylinder power stroke to determine if a misfire is occurring. I am surprised there is no code set for misfire as any misfire over five per cent of the time should cause the check engine light to come on. It could take the diagnostic program longer to set a code if the misfire is random among all the cylinders, so perhaps that is the situation here. The most common causes for misfire are bad spark plugs or a faulty ignition coil. Because spark plugs are relatively cheap, these should be changed first.

Usually an ignition problem will show up as a misfire during acceleration or highway cruising. Your misfire also is there at idle, so instead of suspecting an ignition coil, I would inspect for vacuum leaks in that air intake system and vacuum hoses. This would cause a misfire that could affect all cylinders.

Usually a bad ignition coil will affect only the cylinder it is attached to. If the misfire can be found in only one cylinder, and a scan tool should show this information, then switching the coil to another cylinder would help diagnose the problem. If the misfire changes to the new cylinder, then the coil is the problem. Oil leaking from the valve cover gasket onto the coil boot will also cause a misfire. Unbolt a coil from the valve cover and check to see if there is oil on the boot below the coil. If there is, replace the valve cover gasket and clean the oil off the coil with a solvent.