03 Corolla won't crank

03 Corolla, starter is new, replaced under warranty, old one showed same problem. Starter doesn’t engage / turn when key is torned to start. I can hear the starter relay behind the glovebox click. Pulled wire to solenoid, has 12.2 volts when key is turned. Ambient battery voltage is 13.2. When I jump from battery to solenoid contact on starter, it turns and starts car.

Is that one volt that critical? This was a sudden onset problem, no gradual failure…

Any ideas greatly appreciated.

You probably have bad or dirty battery cables. Voltage readings alone will not test the integrity of the cables. Google voltage drop testing. You will probably find your problem.

Test the voltage at the two starter motor terminals with everything connected. Both should measure at least 10.5 volts with the key in “start”. Do they? This test isn’t diagnostic if done w/ the wire disconnected from the starter motor. Make sure to measure the voltage between the terminal and the starter case. I expect you’ll find the voltage is less than 10.5 volts at the solenoid terminal (terminal “S”).

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The starter relay you hear clicking may be the culprit… See if you can swap that relay with another one in the fuse box…often there will be ones you can swap as they are the same part.

You have already proven out that the starter and battery and cables function when you jumped the batt wire to the solenoid trigger… so… move on to why your signal voltage is dropping…it has to go thru the starter relay…

If you pull the relay and measure your voltage at terminal 30…then jumper 30 to 87…this will send 30’s voltage directly to the starter solenoid via that wire you already measured the voltage drop on.

If this works…the relay was the problem.

Make sure the ignition wire that goes to the solonoid is free of dirt or corrosion.Its a clip on connector.