Starter Motor Troubleshooting Tips DIY - How to diagnose starter problems

Video to show how to trouble shoot a starter motor when it won't start the car. Provides a procedure to follow to diagnose starter motor problems.

One measurement I didn't have time to add was to verify the solenoid operation by measuring the voltage drop across it while triggered. When you turn the key to START and you get 12V on the trigger wire, put one volt meter probe on the big silver solenoid battery cable nut . Put the other volt meter probe on the lower black solenoid nut attached to the braided wire going to the motor. When triggered, you should see less than 0.1V between the two cable nuts on the solenoid. If you measure more than this then the solenoid electrical contacts inside are pitted or worn out and this is preventing enough current from flowing in the starter to make strong enough torque to turn the engine. Instead of turning the engine you will only hear a clicking noise when turning the key.

Battery Voltage - %Charged
12.6V 100%
12.4V 75%
12.2V 50%

Allowable Voltage Drop in the starter circuit
0.2V from battery +ve lug to starter solenoid silver nut.
0.1V from solenoid sliver nut to braided strap on starter body
0.2V from battery -ve lug to starter body metal.

Category:

Education

Tags:

• bearing01
• Starter
• Motor
• Trouble
• Shooting
• troubleshooting
• tips
• DIY
• diagnose
• no
• start

[imohmed1]

Great video. Very clear. I'm a carpenter with terrible starting probs on my transit. Helped diagnose dodgy corroded connection. Saved £s on replacement starter that the garage misdiagnosed

[bearing01]

@imohmed1 That's awesome. Thanks for the feedback. /John

[xzzx22]

Thank you very much

I'm a technician and you helped me to learn more about the starter, it the same on the generators!!

[bearing01]

@xzzx22 Thank you. /John

[NEMESIS9O9]

So any idea of what it could be? If its not the starter, alternator, or battery?

[bearing01]

@NEMESIS9O9 My first guess would be a dirty (or bad) idle control valve. That or dirty throttle plate. Clean both with carburetor cleaner spray. Next it could be a bad throttle position sensor. It could also be a vane air flow sensor flapper stuck wide open (if you have one) or dirty or bad mass air flow sensor. It could also be a bad engine temperature sensor or crankshaft position sensor or camshaft position sensor. Clean the throttle and Idle control valve first. /John

[NEMESIS9O9]

Thank you John

[bearing01]

@NEMESIS9O9 If the vehicle died while it was running then it's not the starter. The starter only runs while trying to start the vehicle. It wouldn't cause the engine to stall. It could be a bad alternator.. but a bad alternator would run your battery dead and after the battery runs dead the car would stall. /John

[NEMESIS9O9]

My 87 Chevy died while I was waiting at a light, battery is ok. Could it be the starter, if so where can I find it?

[bearing01]

@ManagFTW66 Get up in under and look at the transmission bell housing and you should find the starter somewhere in the mid to upper section of it. /John