If you turn the key of your auto and nothing happens, or the response is anything less than the engine roaring into life, your day might just have got off to an inauspicious start. Ignition switch problems can be highly frustrating because so many things could be going on beneath the hood which prevent the auto from starting. To troubleshoot this problem, you must start at the beginning and then work your way back.
The most common reason for an auto not starting is that the battery is dead, so this is your first consideration. Over time, battery connections become corroded or dirty, which breaks the connection betwixt battery and auto. You should clean your battery terminals and try again. If you have access to a battery tester, use it. If not, jump-start the vehicle. If you are rewarded with an immediate start, all you need do is replace the battery.
If there is no problem with your battery but the starter remains silent, the ignition switch may be faulty. Move the key to the on position and not all the way to start. If you see no red warning light on your dashboard and the battery is good, the fault lies with the ignition switch.
Ignition System Problems
All electrical components can fall victim to corrosion, particularly those that are open to the elements. You could hold a circuit tester to the wire which engages the starter the smaller of the two wires connected to the starter. Be careful to keep your body away from the moving parts of the engine, as it could leap into action at any moment. Ask a friend to turn the key while you check the current. If the starter has current but does not spin, it needs to be replaced.
Next, you should test your ignition coil, which requires a multimeter capable of measuring impedance. If there is no such thing to hand, you can use basic hand tools. If the coil functions not, replace it.
A no-start problem is probably not caused by the distributor cap, however it is a possibility, particularly in wet weather. Remove the cap and look inside for any trace of moisture. If there is so much as one drop of moisture or mist, wipe it clean. Check that the cap is not cracked.
The problem might be caused by a coil wire which is broken or shorting. So you should take a look at the wire to ensure that there are no obvious cracks and test its continuity with a circuit tester.
Fuel-Related Ignition Switch Problems
If the starter spins and sparks fly, the problem must lie with the fuel system. If your auto is fuel-injected, a variety of sub-systems could be the culprit. Serous diagnostic work will be required, but you can performs some actions that narrow it down.
A fuel-injection system has many electrical connections. There is a connector atop each fuel injector, and these should be checked to ensure that they are tight. If you have the equipment, you should perform a pressure test upon the fuel pump. Most people do not, but you can at least check the electrical connections. Test the fuel pump for current while the key is set to on using a circuit tester. Then inspect the fuse.
If the fuel pump functions but fuel still does not reach the engine, the fuel filter might be clogged. It should be replaced approximately every 12,000 miles. If it might be clogged, replace it.
As can be seen, there are actions you can take when your auto does not start, and ignition switch problems need not ruin your day.