Can a car run without relays?
5 ways your starter motor can fail, and what to do about it
The starter motor was late to the game in terms of automotive additions. We’d had the car for over 20 years before Cadillac came along and fitted an electric starter to its 1912 model. Prior to this, we started our cars by manually cranking them to life via a handle protruding from the engine.
We liked this new technology, and by the 1920s, pretty much every car was fitted with one from new. And why wouldn’t it be a popular addition? Hand-cranking a car was hard, and, if you didn’t get your arm out of the way fast enough, the crank handle would happily break it for you. Ouch!
The starter motor works in modern cars the same way it did back then, by engaging ring gear mounted to the flywheel. By turning this quickly, the engine can start. It’s simple physics, but of course, it’s still a lot of work. That little motor working through your flywheel has to earn its keep, and when it’s about ready to give up, one of the following starter motor problems will make themselves apparent.
See how much you could save by replacing the starter motor yourself
1 Start motor engages but the engine doesn’t turn
Assuming your battery is healthy and fully charged, if you turn the key only to be greeted by the clunk of the starter engaging but the motor doesn’t turn, it can mean a number of things. The simplest cause of this sort of fault is a loose or corroded electrical connection.
If there is a fault with the internal windings of the starter motor, bad brushes, or other electrical faults, the starter motor may lack the torque to crank the engine. There could also be mechanical issues, like bad bearings inside the starter, or teeth no longer meshing in the starter or ring gear. If you turn the key and hear only a thunk or click…
What should you do?
- You’ll need to inspect the electrical connections between the starter, battery, earth, and if it is mounted remotely, solenoid. If those are all clean and tight, and none of the cables look to be corroded internally…
- Remove the starter and test it for proper function off of the engine. A starter that is bad mechanically will make ugly noises when spun up and not attached to anything. If it spins freely when not under load, and all the connections were good on the car, chances are the windings or brushes are bad.
2 Starter motor turns but doesn’t turn the motor
A starter motor’s pinion gear is not constantly engaging the ring gear on the flywheel. Instead, the starter pushes the smaller gear out to engage with the flywheel with a part called the Bendix, which is not much more than a big electromagnet. It’s this that pushed the pinion gear out to engage with the flywheel. If you turn the key and hear just a whirring or grinding…
What should you do?
- You’ll need to inspect the starter to check several things. The first is whether or not the starter is bolted tightly to the motor or transmission. Bolts can come loose, and it doesn’t take much movement to interfere with the gears meshing correctly.
- Another potential issue could be that the teeth on the starter or the ring gear may be damaged. Often an indicator of this is if the problem only happens occasionally, meaning there are good and bad spots on the gear, and sometimes it doesn’t mesh.
- Lastly, the Bendix part of the starter can go bad, causing it to not push the smaller gear out with enough force to make it engage fully.
Solution: The starter motor spins, so it still works somewhat. This is typically a mechanical issue. A starter motor specialist should be able to rebuild the unit and replace the worn parts or tired Bendix. If, however, the ring gear on the flywheel is damaged, it’s going to be a gearbox-off job to fix it.
What to Do If Your Car Won’t Start
Before you call a tow truck, it’s worth trying a few of these tips to get your car up and running.
Most people don’t keep a set of mechanic’s tools in their trunk. So when your car won’t start and you get stranded with a dead engine, you feel pretty helpless. But don’t give up right away if your car will not start. We’ve compiled a list of tricks you can try when your car won’t start, and none of them require tools. They’re arranged by symptom, and you’ve got nothing to lose by trying them if the car cranks but won’t start. Of course, they won’t fix the root problem, but one of them just might get the engine started so you can head to the nearest mechanic to have the problem fixed. Here are some things to try if your car won’t turn over.
If the Car Clicks When Trying to Start
If the car clicks when trying to start, but still won’t start, this can be caused by a weak battery, dirty battery terminals, a worn starter motor or a stuck solenoid. If might just need a jump start, but there are a few tricks to try before breaking out the jumper cables or electric jump starter.
Try Cycling the Key
If your car turns on but won’t start, turn on the dome light and watch it while you try to start the engine. If the light goes out, it’s a sign the battery is really weak—almost dead. To heat up the battery, terminals and starter, try the key cycling trick. The trick is to turn the key to the start position repeatedly about 10 times in a row. Stop and wait five minutes. Then try to start the engine. But if the dome light stayed bright when you turned the key, move on to the next trick if your car won’t start.
Try Tapping on the Battery Terminals
There’s no way to clean corroded battery terminals when you’re stranded without tools. But you can try to move or at least jar the terminals enough to make better contact. Smack each battery terminal with the heel of a shoe to rotate it slightly around the battery post if the car will not start. Then try starting the engine.
Try Tapping the Starter
If you have access to the starter motor, try hitting it with the tire iron from your car jack. Sometimes, the electrical contacts get stuck and can be freed by tapping on them.
If There’s No Click When You Turn the Key
Try Shifting the Shifter
With your foot on the brake, move the shift lever to the neutral position and try starting the engine. If that doesn’t work, move it back to park and try it again. Moving the shifter sometimes reestablishes electrical contact inside the transmission range selector (also known as the neutral safety switch).
If the Engine Cranks But Won’t Fire Up
Here are a few tricks to try if the engine cranks but the car won’t start.
Try Swapping Relays
With the radio off, turn the key to the run position and listen for a two-second buzzing sound. That’s the fuel pump priming the injection system. If you don’t hear any sound, the fuel pump relay may be bad or the pump may be on its last legs.
First, find the location of the fuel pump relay in your owner’s manual or on the legend for the under-hood fuse box cover. Yank the fuel pump relay straight up. Then locate another relay with the same part number and swap it with the fuel pump. Push it straight into the socket. Try starting the engine afterward.
Try Smacking the Fuel Tank
If your car won’t start, hit the bottom of the fuel tank several times with the heel of your shoe to jar the fuel pump motor. Then try starting the vehicle.
Try Un-flooding a flooded engine
If you smell gas, the engine is flooded. Press the accelerator pedal to the floor and hold it there while you crank the engine.
Try Tricking the computer
A vacuum leak or funky temperature sensor can result in an air/fuel mixture that’s too lean to start a cold engine. If you’ve tried all the other tricks shown here and your car won’t start, press the accelerator halfway and try to start the engine. That’ll tell the computer to add more fuel.
Why Starter Keeps Cranking With Key Off?
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.
Table of Contents
- Root Causes Of Randomly Cranking Starters
- How To Test a Starter Without Removing It
I’m a car mechanic with 23 years of hands-on experience in the automotive world.
I created this blog to share my passion and extensive knowledge with fellow car enthusiasts and DIYers.
Throughout my career, I’ve gained expertise in automotive repair, maintenance, and troubleshooting, which I now happily pass on to my readers.
My commitment to excellence and continuous learning has made me a trusted authority in the industry.
I’ll provide you with practical tips, reliable advice to help you tackle your car-related challenges with confidence.