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Starter clicks but wont start the engine

Starter clicks but wont crank the engine

How to diagnose and fix a starter clicks but won’t start the engine

If you turn the key to start your engine and your starter clicks but wont start the engine, this may be the article for you.

The clicking sound can be coming from the small starter relay in the fuse box that sends power to the starter solenoid. The starter solenoid’s job is to connect the large gauge battery cable to the starter so 400 amps can push the starter drive into the flywheel and rotate the engine.

How a starter works

Let’s take a look at a typical starting system.

Power flows from the battery positive terminal to the IGN switch. When you turn the key to START, power flows through the IGN switch to the control coil of the starter relay in the fuse box. Power also flows from a fuse to the contact side of the starter relay in the fuse box. At this point, the PCM is checking to make sure you’ve inserted the proper key. This is the immobilizer portion of the PCM and is designed to prevent auto theft. If the PCM determines you’ve inserted the proper key, it provides ground to the starter relay control coil. Once the coil engergizes, it closes the starter relay contacts and allows power to flow to the starter.

But first, the power has to pass through either the manual transmission neutral switch or the automatic transmission park/neutral switch. Those switches prevent starter engagement if the transmission is in gear.

Finally, power flows to the starter motor solenoid. The magnetic solenoid pulls a plunger forward which throws the drive gear into the flywheel. The solenoid also connects the main battery cable to the starter motor, allowing it to draw hundreds of amps to crank the engine.

The starter relay in the fuse box make a faint click sound. But the starter solenoid at the starter makes a much louder click. If the starter relay in the fuse box clicks but not the starter solenoid, check these items:

• Is the transmission in the park or neutral position? In an automatic transmission vehicle, move the shifter from park to neutral and try again. If the starter operates, the park/neutral switch could be bad. In a manual transmission vehicle, depress the clutch several times and try starting again. If the starter engages, the problem can be a worn neutral switch.

• The battery may be discharged. It doesnt’ take much power to move the contacts in the starter relay in the fuse box. But it takes much more power to operate the starter solenoid.

• The battery terminals may be corroded causing too much electrical resistance.

Clean the battery terminals

I know you really want to find a serious problem and spend (waste) lots of money replacing things that aren’t broken, but the first step in diagnosing a problem where the Car starter clicks but wont start the engine is to clean the battery terminals and ground cables connections.

car won't start, dirty battery cables, clean battery cables

Look at the corrosion on these battery cables. And you wonder why it won’t start?

Then test the battery condition. To read how to do that, read this article.

Looks are deceiving

The battery terminals may look OK, but when you’re trying to run 300 amps through them, even the smallest bit of corrosion can cause a huge voltage drop. The voltage drop will reduce voltage to the point where the solenoid engages, but can’t power the starter. That’s why the starter clicks but wont start. I’ve seen plenty of cables that looked fine but resulted in starting problems. So humor me on this and start by cleaning both battery terminals. All you need is a socket set and a battery terminal cleaning brush.

dirty battery terminals, click but no start, starter clicks,

Remove the battery cable terminals and clean the inside of the terminal and the battery post with a battery cleaning brush

When you’re done cleaning the battery terminals, clean the negative cable where it attaches to the engine. Then clean the battery negative where it attaches to the body. Finally, clean the cable that goes from the engine to the firewall. Still won’t start? Ok, at least you tried the inexpensive fix first.

clean battery terminals, starter clicks once, starter clicks, car won't start

Neutralize battery corrosion and protect against future corrosion with these product. Find them at any auto parts store.











Diagnostic tip if you don’t have tools.

People on auto forums always say “it can’t be my battery because the dash lights and radio come on when I turn the key.” Well, I’ve got news for you. Those components take almost no power to run. Energizing the solenoid on a starter motor takes a LOT more power. Here’s a quick diagnostic trick to check the condition of your battery:

1) Turn on the dome light.

2) Try to start it while watching the dome light. If the light dims by quite a bit, that’s an indication that power is getting to the starter and it’s drawing enough power to dim the light. Diagnosis? Perhaps a bad starter. But it could also be corroded connectors that are introducing a substantial voltage drop.

3) If the light doesn’t dim at all, then power isn’t even getting to the starter. The likely cause would be a bad or out-of-adjustment neutral safety switch. (If you own a Ford, it’s called the transmission range selector switch (TRS) and they have a high failure rate) You’ll need a digital multimeter and a wiring diagram to test out the neutral safety switch.

4) Remove a shoe and TAP (not hit) the battery terminals. That may cause enough vibration or movement to get you a good enough connection to turn the starter. If it works, clean the battery terminals ASAP.

NOTE: Do NOT use a 12V test light unless it’s rated as “computer safe.” Many new cars run the neutral switch through the anti-theft system and those are powered by computer. A 12V incandescent test light can fry those computers.


© 2012 Rick Muscoplat

Posted on by Rick Muscoplat

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