Now and then, a car can try to start on its own – it might even try to crank without having your keys in the ignition.
Normal wear on the starter and engine can cause minor malfunctions. But what causes it to crank with the key turned off?
If the switch inside your ignition is stuck, it can continually cause your starter to crank. Faulty wiring or malfunctioning starter parts can also cause continuous cranking after starting your vehicle or removing the key.
Root Causes Of Randomly Cranking Starters
Your starter can crank after you remove the key, with the engine running, or seemingly on its own.
There are a few likely culprits for this kind of starter issue, and fixing them comes with varying degrees of difficulty.
The first thing that causes your starter to crank without a key is when the starter is locked or stuck.
The engine cranks when the starter relays in the ignition touch – turning your key in the ignition causes the two contact points to touch.
The contact points can get stuck touching each other, causing the starter to crank after the vehicle has started or when the keys are removed.
Solving the issue could be as simple as moving the contact points apart and securing them where they are supposed to sit.
The starter can also crank when you have a bound cylinder, which means your ignition cylinder is locked. A bound cylinder is caused by the normal wear and tear on your ignition cylinder from inserting or removing your key.
Most vehicles have four stages to ignition once you insert your key. The first unlocks the steering wheel; the second turns on the electronics; the third turns on the fuel system; and the fourth cranks the starter motor.
Modern vehicles may have the first stage happen when the key is inserted or have a multi-stage system for push-to-start vehicles.
Over time, the cylinder can lock or wear out. It causes irregular events, from the vehicle not starting to sputtering or even cranking when you don’t intend it to.
You can diagnose this issue by trying to rotate the lock cylinder of the vehicle. You have a bound cylinder if it stops or doesn’t move.
You can then try lubricating the cylinder, but you must always use a graphite solution. WD-40 or silicone lubricants will worsen the issue because they trap dust and grit.
Trapped debris creates friction and can cause the cylinder to lock completely without hope of repair.
The third reason for unexpected cracking is electrical issues.
Faulty wiring in any part of the vehicle causes problems. If the starter isn’t getting enough power, it has a low voltage problem.
Lack of power can cause it to work intermittently as it receives enough energy to signal the starter to crank.
Loose connections or fluctuating power can also cause the starter to fire even after the keys are removed.
The first thing to do if you suspect a low power issue is to check the battery. Use a voltmeter to confirm that it has sufficient charge and either charge or replace the battery if it doesn’t.
If you’re still experiencing issues, you’ll need a mechanic to look for faults in your wiring system.
Getting a new starter relay is often the best fix for all of these issues. If the relay is the source of the problem in any way, this should resolve it.
If a new relay doesn’t fix the starter issue, look into wiring problems and ensure your lock cylinder will rotate.
How To Test a Starter Without Removing It
Your vehicle’s starter can cause several different issues aside from trying to crank with the keys turned off.
Faulty starts, cranking without catching, and even not starting at all can be caused by problems with the starter.
If your vehicle fails to start, one of the first things you should do is test your starter. It’s a bit technical and requires some knowledge of how electricity in a vehicle works.
Always take proper safety precautions before attempting any DIY vehicle tests or fixes.
That said, conveniently, you can test the starter without removing it from the vehicle.
Before you start, be sure to turn off the engine completely and put your vehicle in park.
You then need to locate a pair of jumper cables. You’ll use the jumper cables to bypass the starter completely and send power to the starter motor and drivetrain.
Connect one end of the red cable to the battery’s positive terminal. Then connect the other end to the positive terminal of the starter motor.
Once connected, the starter should spin and try to crank. If it does spin/crank, your starter was the issue.
Your next step will be to replace or repair the starter.
If it doesn’t spin/crank when connected, you must perform another test to determine the problem.
Connect the black cable as a ground between the drivetrain and the negative terminal of the battery.
Touch the red cable to the positive terminal of the starter. If it cranks, the problem is a bad engine chassis ground.
If it still doesn’t crank, the starter motor may be completely locked or irreparable.
You could also have issues with another wiring in your ignition or starter motor, but this test should point to whether the wiring or your starter was the cause of your problem.
Your starter may try to crank when the key is turned off if there is a problem with your starter, wiring, battery, or starter cylinder.
You can check your starter without removing it from the vehicle and try to diagnose the problem yourself.
If you can’t find the issue, don’t continue cranking your vehicle. You could damage it further, and it’s best to call a mechanic to look into the problem.