Good battery, good starter, but it either clicks, or does nothing when you turn the key.

This time of year when it starts getting colder is when most batteries and starters fail. The engine oil is thicker, it takes more torque to crank, the battery puts out less amperage when it's colder, blah, blah blah.

If you've already tested your battery (or replaced it), and ditto for the starter, but it still does NOT crank, here's your diagnosis path. It's a how-to for voltage-dropping your starter circuits ---- and cheating, to save time.

Before you voltage drop ANYTHING you need to take both your battery terminals completely OFF the battery. I have seen them look PRISTINE but they were ever-so-slightly loose and there was a THIN layer of white lead oxide between the terminal and the post causing all SORTS of problems, like not charging, failure to crank, etc. Go buy a $5 battery post brush at Autozone/Checker whatever and clean your posts, and re-assemble, and if you're a pro, spray it with red battery terminal corrosion protector available from NAPA and elsewhere.

If they are the bolt-on, "repair" type cable ends instead of the "factory, crimped on" terminals you need to unbolt them and inspect where they smash the copper wire, and perhaps refresh (or replace) that if its full of corrosion.

If that doesn't solve your problem, it's time to voltage drop some circuits.

One on the big heavy red/positive cable going to the starter, the ground connection, and the other on the smaller wire coming from the ignition switch to the solenoid. .

(But read this WHOLE article before you get out your meter and start voltage dropping)

Take your meter, set it on volts, and attach the black lead to battery minus (B-) using an alligator clip or whatever.

First, take the red lead, and touch it to B+. See what the voltage is. Should be around 12.6 if the battery is fully charged.

This step confirms you have your METER on the right setting, unbroken leads, etc. If your battery reads less than 12.3 YOU HAVE A PROBLEM. 12.6 is a fully charged battery, 12.4 is 50% charged, 12.2 or less and you probably have a failed cell in the battery.

MEMORIZE: You CANNOT diagnose electrical problems unless you have a KNOWN GOOD battery in the vehicle.

Without disconnecting anything, touch the red lead to where the main positive cable attaches to the starter/ solenoid.

Before you crank the motor, it should read 12.6 also.

Make sure you're in neutral, brake set, and have someone attempt to crank the motor. With a good battery, and the starter actually cranking, the voltage should not drop below 9V.

Below that, and either your battery terminal is corroded, the cable is damaged, or the lug bolted to the solenoid not tight, corroded whatever.

Next, you need to voltage drop the OTHER leg of the circuit -- the negative side.

The negative (black) battery cable should be bolted somewhere directly to the block. Start by visually inspecting, removing, cleaning, and retightening that, and looking for damage to the cable. Make sure someone didn't paint the engine block and bolt the ground right on top of non-conductive paint!

Now take your meter, put the red lead on B+, touch the other lead to the CASE of the starter --- any metal part should do, and crank. Again, it shouldn't drop below 9V WHILE actually cranking, spinning.

Next is to voltage drop the actual starting circuit, the lead coming from your ignition switch.

If you disconnect it and have someone turn the switch, it should show 12.6 volts also. But as I taught in the article, SO WHAT! It's easy to show 12.6 volts when there is no current flowing, no load on the circuit. It's like static electricity --- millions of volts, but no amps! Meter doesn't care!

So leave the starter switch input connected, and either probe it , or stab the wire with a t-pin, you must establish a connection WITH IT STILL connecting the switch and the solenoid.

Again, have someone crank it while you watch the voltage.

If it's below 9 volts or thereabouts, you may have damage to that wire, or whatever is FEEDING 12V to your ignition switch.

There's actually a much SIMPLER way to determine if the crank signal is the problem --- just run a jumper wire from B+ directly to the starter switch input on the solenoid.

If THAT causes it to crank, but turning the keyswitch does NOT, then you know the problem is in the keyswitch circuit.

Again, that is so much faster, I'd do that BEFORE I spent time voltage dropping anything.

So now that I've taught you how to voltage drop circuits, I'll teach you how to cheat and skip actually doing it 95% of the time.

Connect a pair of jumper cables from the battery terminals directly to the starter, but only ONE AT A TIME.

(not one AFTER another, only ONE pair connected at any one time)

Hook up a black cable from B- to somewhere metal on the starter, turn the switch, and see if it cranks.

If it does, then your ground terminal / battery cable has a problem.

Unhook that, and hook up a red jumper cable from B+ to the post where the fat red cable normally attaches to the solenoid. Turn the switch, and see if it cranks.

If it does, then your positive cable / lug has a problem

If NEITHER of these "fix" the problem you have a failed starter, seized motor, bad battery, whatever. If it does fix it, use voltage dropping to determine WHERE you have a problem preventing adequate current from reaching your starter.