The starting and ignition systems are vital to your car. They both require electricity to operate. The ignition system is your car’s heartbeat. The starting system, then, must be the first cup of coffee in the morning. And we all know what some people are like if they don’t get their coffee fix! This article guides you through common repairs to starting and ignition systems. Reading over the instructions can help you decide whether you want to tackle the project yourself or hire someone to do it. Remember that although you don’t know as much about your car as a trained mechanic, you have a greater need to make sure the job is done right and at a reasonable cost. The repair procedures in this article are typical for most modern cars. Refer to the manufacturer’s manual or an aftermarket service manual for specific instructions and details for your car.
You Can’t Get ‘Em Up in the Morning
Here’s where the job of the starting system is like the task of your first cup of coffee. The starting system turns the engine quickly enough to enable it to start-at least, that’s what it does when it operates properly. Components of the starting system include the battery, the starter motor, the starter solenoid, and all the wires that connect these parts. How does the starter system work? As you turn the ignition key to the start position, an electric signal runs along the wire to the starter solenoid. The solenoid is told to deliver electricity from the battery to the starter motor. It does so until the ignition key is released from the start position. The end of the starter motor has a small gear that meshes with the teeth around the edge of the engine flywheel. The gear rotates the flywheel. At the same time, the ignition system is delivering a spark and the fuel system is supplying a fuel/air mixture to the engine. The engine starts .. .in theory, and if everything is in good working condition. If the engine doesn’t start, the cause could be one of many things, including the starter or solenoid. Before you consider repairing the starter, however, check one more thing: the interlock. An interlock stops something from happening if all conditions are not met.
Most cars now have an interlock that must be operated before the signal to start is sent to the solenoid. The interlock on cars with manual transmissions requires that the clutch pedal be pushed in before the car is allowed to start. On automatic transmissions, the interlock requires that the gear selector be in the park or neutral position. So, before you begin to repair your car’s starter or solenoid, find and test the interlock, fuses, and battery. Finding the interlock may be the operative term here because some are mounted near the clutch pedal, and others are in the steering column or mounted near the starter. Testing an interlock means using an ohmmeter to see whether the circuit is open or closed (read the ohmmeter’s instructions) when it’s activated.
One more tip before we (that’s like the nurse asking how we feel today) get our hands dirty: Have someone turn the ignition key to the start position. If, standing near the engine, you hear the solenoid click, it’s working. If you don’t, it’s not working, assuming that you’ve already checked the battery and any starter system fuses. A starter motor should give your car 75,000 to 100,000 miles of trouble-free service-and more with proper maintenance.
Troubleshooting Electrical Problems
Here are some guidelines for troubleshooting starting and ignition systems:
- Make sure the automatic transmission is in the correct gear or that the clutch on a manual transmission is fully depressed (or at least morose).
- If your car won’t even make a noise when you try to start it, first check the battery terminal connections. Then look for other loose connections in the starting and ignition systems.
If your car won’t start, causes may be a discharged battery, loose or broken wires, a faulty starter or solenoid, or a faulty ignition switch or neutral interlock., Also Dirty battery connections can cause fuel-injection systems to hesitate or surge. Keep those connections clean!
Replacing Your Car’s Starter
To replace the starter motor and/or starter solenoid, follow these steps:
- Remove the negative or ground cable from the battery (see Chapter 9, “CAR Quarterly Check Up,” for tips on identifying cables).
- Find the starter. No, it doesn’t look like a coffee cup. It’s a round motor about three inches across located at one side or the other of the flywheel. The flywheel is located between the engine and transmission. The solenoid is probably mounted on the side of the starter. If not, trace the wire to the solenoid, which is probably mounted nearby on the firewall.
- Disconnect the battery cable and any other wires to the starter or solenoid.
- Remove the starter and solenoid. This usually means removing two bolts that mount the starter on the side of the engine or the bellhousing (clutch cover). The starter weighs a few pounds, so be careful not to drop it when the last bolt is loosened. If the solenoid is not attached to the starter, remove it from the firewall.
- Repair or replace the starter and solenoid. Unless you have the equipment and knowledge to repair or rebuild a starter (it’s a specialty, so I’m assuming you don’t), buy a replacement at an auto parts store or automotive electrical shop. A helpful counterperson at either place should be able to test your starter and solenoid before you buy a replacement.
- Reinstall the starter and solenoid. Tighten and check all connections before trying to use the starter.
Diagnosing and Treating Ignition Ills
An automotive ignition system has a pretty simple job: to supply a spark to the engine at the time it’s most needed. To do so on today’s fuel-efficient cars requires nothing short of a computer, however. That’s why cars have become so difficult for the owner to repair. Fortunately, the technology has stabilized somewhat and the newest cars at least have some logic to them.
In addition, cars are using more modularized systems. No one, not even mechanics, repairs ignition systems. They replace components that test bad. So can you. Using a simple volt-ohmmeter (VOM) and the car’s service manual, you can probably track down and solve many ignition system problems, saving yourself many dollars.
What Makes Them Go?” high-voltage electricity comes from the ignition coil, and is passed to the appropriate cylinder by the distributor. All distributors, in both older and newer cars, are driven by the engine’s camshaft. The distributor is advanced or retarded as engine speed changes by electronics (newer cars) or a vacuum/mechanical advance system (older cars). Computerized ignition systems also sense and respond to changes in engine speed, coolant temperature, throttle, vacuum pressure, and, seemingly, the manufacturer’s daily stock value.
The ignition switch in a car used to be a simple, three-position switch: Off, On, and Start. Today, it’s become more complex, as so many other automotive components have. The ignition switch is now linked to sensors, anti-theft devices, interlocks, and the bank where you have your car loan. Fortunately, failure of an ignition switch typically is traced to a loose wire. That’s something you can fix-if you can find it.
To repair an ignition switch and wiring, follow these steps:
- Find an electrical schematic for your car’s ignition system. It’s usually printed in the car’s service manual or in an aftermarket service manual. If not, you might have to order one through the dealer. The schematic tells you what’s in the ignition wiring system, such as interlocks and sensors, besides the switch. It might also identify their locations.
- Visually trace and inspect the ignition switch and wiring for loose wires, burn marks, or other damage. Reconnect or replace as needed.
- Use an ohmmeter to test continuity of the ignition switch and wiring. Replace defective parts as needed.
It’s Coiled, But Is It Ready to Bite?
The coil converts low voltage (12 volts) from the battery into high voltage (30,OOO-plus volts). It either works or doesn’t. There are two electrical circuits within a coil, and both must work. If they don’t, replace the coil as a unit.
To test and replace an ignition coil, follow these steps:
- Find the coil. On some cars, it’s installed in the distributor, which requires you to remove the distributor cap. In other cars, it’s mounted on the engine block or on the firewall. Coils located outside the distributor are typically cylindrical, with two small wires and one large one.
- Use an ohmmeter to test continuity. Your car’s service manual identifies the coil’s primary and secondary circuits. Measuring continuity across two points in a circuit shows whether the circuit is letting electricity pass through it (a closed circuit) or not (an open circuit). Verify that both coil circuits are not only closed, but also have the resistance (in ohms) recommended by the manufacturer.
- If the coil is defective, replace it, following instructions in the car’s service manual. If not, spend the money on sugar donuts.
Replacing Sensors and Control Modules and Distributors
There are many other electrical components in your car’s ignition system: sensors, a control module, and a distributor. Each can be tested using a volt-ohmmeter (VOM) and replaced as needed. It’s critical that you compare the test results to those from the car’s manufacturer.
To test and replace electronic ignition components, follow these steps:
- Locate your car’s distributor and electronic ignition, also called an ignition control module (ICM). The distributor operates from the camshaft, so it is mounted on the upper half of the engine. The ICM controls the ignition system and is mounted either within the distributor or nearby. Breaker-point ignitions are mechanically rather than electronically controlled.
- Remove the distributor cap or ICM cover as necessary. Inspect the unit for obvious problems, such as a cracked cap or rotor, loose wires, or debris. Clean or replace as needed.
- Following manufacturer’s recommendations, use an ohmmeter to test continuity for each component. Find and test sensors as well as the ignition control module.
- If necessary, remove and replace the distributor as a unit. Make sure you note the rotor’s exact position so that you can reinstall the new distributor with the rotor in the same position.
- Carefully document the steps required for easy reference at your next (and last) party.