Most of us rely on our vehicles to take us everywhere. We jump in the driver’s seat, turn the ignition key (or push the START button) and away we go. But what happens when you turn the key, or push the button, and nothing happens? You may hear the starter slowly turnover a few times then a rapid clicking from somewhere under the dash or hood. After that… silence.

Now the question is, what is causing the problem? It could be the battery, starter or alternator. Let’s take look at the reasons why your engine won’t turn over and discuss ways to fix it.

Battery

• Dead battery. If your battery is already past its advertised warranty period, it’s living on borrowed time. Replace it regardless of what else you may find. The warranty date is often noted on top of the battery. As batteries age, they often lose their charge because of sulfated or shorted cell(s) and can’t be recharged. Occasionally, an alternator will overcharge a battery causing it to overheat and fail.
   
• Battery was discharged. Often, accidently leaving the headlights, an interior light or an aftermarket accessory light on will discharge the battery. Check all lighting including the headlights, under hood light, rear hatch lamp, under dash lights or dome light.
   
• Parasitic draw or drain. Your battery may also be losing its charge overnight or over a period of a few days due to what’s called a parasitic draw or drain. Parasitic draws can be caused by an electrical component malfunction or a short circuit causing unintentional current to flow through a circuit. An example of a parasitic draw would be if the dome light remained lit with the key out of the ignition and all the doors closed. In this case, an internal body control module malfunction is causing the light to stay on and drain the battery. Parasitic draws can be tricky to diagnose. Here are two excellent resources to further explain what parasitic draws are and how to diagnose them. See Parasitic Draws Explained or for more pro DIY level info Parasitic Draw Test.
   
• Battery cable issues. Cables that are loose or corroded can cause a starting and charging problem. Inspect battery cable connections at both ends, especially the negative (- black) cable. It’s notorious for coming loose where it connects to the engine block, body or frame. Check the positive (+ red) cable end where it attaches to the starter motor and/or a power distribution block or terminal. Clean and tighten the cable ends at the battery terminals and other attachment points.
   

IMPORTANT NOTE: Stiff cables are a sign of corrosion lurking unseen under the insulation. Most often the corrosion is closest to the battery terminal. Replace any cable that is not very flexible or there is white/green corrosion visible on the cable ends.

• Battery is not being charged. It is possible that the alternator is not charging the battery. The battery can often be recharged, but if the charging system issue is not repaired, the battery will discharge again while you’re driving (See more alternator information below).

Starter

Another reason the engine may not turn over is because there is a problem with the starter or starting system components or electrical circuits. Listed below are some of the most common problems.

• Starter malfunction – The starter could be worn out or damaged internally. Also, verify there is battery voltage at the positive battery terminal on the starter. If that is good, check for battery voltage at the starter solenoid wire while turning the ignition key to the start position. If it’s okay, try lightly tapping the body of the starter with a wooden hammer handle or something similar while someone holds the key in the start position. If the starter works when tapping on it, replace the starter. NOTE: If the starter turned the engine over slowly a few times before the battery died, the starter is not likely the cause.
   
• Starter relay is bad – When you turn the key to the start position, the starter relay should make an audible click. Another easy starter relay test is to check for battery voltage at the starter solenoid terminal when turning the key to the start position. You can try swapping the starter relay with another relay of the same type. Both relays will be in the fuse and relay box under the hood.
   
• Powertrain control module (PCM) does not see a “start” signal – You will need a scan tool to allow you to see if the PCM is receiving a start signal from the ignition switch.
   
• Clutch pedal switch or Park/Neutral position switch is bad – A scan tool will be the fastest method to check switch function. In a pinch, you can try shifting the transmission through all the positions a few times, then put it park or neutral and try starting the engine again. The clutch pedal switch wires can be connected or jumped together in a pinch. It’s located on the clutch pedal bracket.
   
• Bad starter solenoid failure or a broken/disconnected wire – Replace bad solenoids either individually or with the starter. Broken or disconnected solenoid wires are common, especially after work has been done near the wire. Repair or reattach the wire to the solenoid.
   
• Ignition switch or push-button switch malfunction – It’s best to use a scan tool to verify the ignition or push-button switch is working. You can also try cycling the key on and off a few times or push the start button repeatedly. Sometimes a worn switch has a few starts left in it.
   
• Security alarm or theft-deterrent system glitch – With a scan tool, check for diagnostic trouble codes (DTCs) related to the security system. You can also check system status.
   

NOTE: A scan tool is amazingly effective when it’s used with the manufacturer’s diagnostic information. Refer to the manufacturer’s starting and charging system test procedures and diagnostics in ALLDATAdiy.

Alternator

Installing a new battery may start the engine and get you back on the road, but that fix may be short-lived. If the alternator is not working, the vehicle’s electrical system will drain the battery’s charge and the engine will die while you’re driving or fail to restart the next morning. Always check the charging system when replacing a battery to avoid future issues.

Seven signs your alternator is bad

1. Headlights are dim and don’t brighten when revving the engine are signs the alternator is not charging the battery. NOTE: Burnt light bulbs are often a sign of alternator overcharging.
2. Battery or Alternator warning light stays on, or the charging system gauge in the dash reads low
3. Dead battery
4. The engine loses power or stalls
5. Malfunction indicator light (MIL) lights up (Also called check engine light or CEL)
6. Alternator makes a whirring, clicking or grinding noise
7. Power accessories may not operate correctly (power windows are slow or seat warmers are cool)

Reasons why alternators fail

• Alternator internal parts wear out or fail (internal voltage regulator, brushes, bearings, diodes, slip rings or broken stator wires). If the alternator does not pass charge system tests or is making weird noises, replace alternator (see battery/alternator test below).
   
• Bad external or internal voltage regulator. Replace an external voltage regulator, charge the battery, then retest the charging system. In some cases, you can replace an internal voltage regulator, but it’s usually more cost effective to replace the alternator as a unit.
   
• Lack of a charge signal from the powertrain control module (PCM). It’s best to use a scan tool and OEM diagnostic information to verify communication between the PCM and the alternator. You can also check and clear any diagnostic trouble codes (DTCs) that may have been set due to lack or voltage or an overcharge condition.
   

NOTE: On computer-controlled charging systems, too high or too low voltage can set numerous DTCs in different modules and turn the MIL and the battery warning light on. Be sure to clear all the related DTCs after you’ve fixed the charging system.

For more in-depth alternator/charging system testing specific to your vehicle, refer to charging system testing procedures in  ALLDATAdiy.  Also find helpful alternator testing procedures here: How to test an alternator.