Free Auto Repair Advice by Professional Mechanics
Troubleshooting
/ Engine Will
Not Crank
Car Engine Will Not Crank Over
The electrical system of your car has several different voltage
and amperage demand systems. The engine starter circuit is designed to carry 12 volts
at high current (Amperage). This is why a battery cable is larger in diameter compared
to other wires in the electrical system. When the ignition key is activated the
starter will turn the engine over. If it doesn't we have listed below some of the most
popular causes for starter non-operation.
Troubleshooting Procedure A. Test Electrical System Voltage.
The best way to test for electrical system voltage is to use a voltage meter
(voltmeter).
Attach the voltmeter leads to the positive and negative terminals of the
battery. To check a battery surface voltage, remove the positive terminal protective
cover and connect the +positive side meter lead (red) to the positive side battery
terminal then connect the - negative (black) side meter lead to the negative
battery
terminal. With the vehicle not running and sitting over night the
battery voltage should be between 12.4 and 12.6 volts. To test the system
without a volt meter activate the headlights, if they illuminate brightly the electrical system
probably has sufficient voltage. If
the headlights are dim or not working the battery charge is either low or the battery has failed and needs
replacing.
Checking Battery Voltage
B. Starter Voltage/Amperage
Draw
Test. Turn the headlights on and observe, activate the ignition key to
crank the engine over. If the headlights stay bright the electrical circuit is
not connected, therefore no voltage drop. A popular reason for this is the
winding inside the starter has shorted or the
starter armature brushes have worn out and replacement is recommended. If headlights
dim way down this indicates your battery is weak and needs either replacement or
recharge. As a rule of thumb, a typical
car battery will last three to four
years before replacement is needed.
C. Check Neutral Safety Switch/Clutch
Safety Switch. A neutral or clutch safety switch is used to disengage the
electrical circuit from the ignition key to the starter motor as a safety
device.
Automatic transmission vehicle gear selector needs to be either in park
or neutral before the engine will crank (Make sure the parking brake is
activated). If the gear selector is in any of the other
gear sections the engine will not crank over. A
standard transmission vehicle
the clutch
pedal needs to be fully depressed before the engine will crank over. To
test this circuit an automotive test light is needed. Attach one end of the test
light to engine ground and the other end to the starter trigger terminal of the
starter solenoid (small wire). The test light should illuminate when the ignition switch is
activated (Crank engine over). If the test light illuminates the starter
motor/solenoid has failed and needs to be replaced. If the test light does not
illuminate suspect a neutral safety switch or clutch safety switch. A wiring
diagram is needed to trace power from the ignition switch through the safety
switch and down to the starter solenoid. Replace failed components as needed and
recheck system.
Starter Solenoid (appearance may vary)
D. Testing Anti Theft Device.
Some cars have an
anti theft system that will not allow the starter to operate. If this system
malfunctions the car will not crank over even after the alarm has been disabled.
To test this system, observe the "Security" light on the dash or instrument cluster.
If this light flashes while the key is being activated the security system is in
failsafe mode. If you have an aftermarket alarm system in your car and you think
it may be the problem locate the main system interrupted relay and bypass main
control circuit. If car cranks over the alarm system has failed and replacement
is needed.
E. Check for Internal
Engine
Damage. If your engine has had a major malfunction it will not turn over. To
check for this condition install a socket wrench on the front crankshaft bolt,
then try to rotate. The engine will turn with a certain degree of difficulty but
it should rotate a full 360 degrees (clockwise). If the engine doesn't turn disassembly is
required, repair as needed and reassemble.
For exact specific repair procedures for any of the steps above visit our
online repair
manual page.
Troubleshooting
/ Engine Will
Not Crank
Check Manufacturer Specific Engine
Will Not Crank Questions and Answers
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