Quote:
Originally Posted by GTP Dad
I know you don't have a lot of money but change the entire positive wire leading from the battery to the starter not just the end of the cable. I suspect that you have an internally corroded wire that is high amperage and that is why the car will start with a boost and not the single battery. This happens when the wires get old and can draw so much current during the starting phase that the battery cannot supply enough to start the car. This is the only thing that I can think of that may be causing the issue.
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That could be tested by the same way that Eric in the video did...
Put probes on battery, try to start. Voltage should stay over 10V. If not, you could have a battery problem OR a starter OR engine problem or a mix of all.
Put a probe on the starter "big wire", put the other probe directly on the battery positive (if you can't, go to the connector...)
Then try to start. The voltage read should be very low. If you read an high voltage (let's say more than 2V) then your wire lose lots of voltage and need to be replaced.
If you read close to 0V, then one probe to the starter body, one to the battery negative terminal. Try to start. If high volt, you have a ground failure. If close to 0V then the ground wire is fine.
If both tests test ok, body of the starter and starter small wire. Should read about 12V when you try to start. If you do not then look at why!
Basically, the small wire power the solenoid, which pull on a lever, that push out the gear out of the starter so it engage in the flywheel, which is bolted to the engine. That solenoid also have a "switch" that connect the big wire to the starter motor.
The proper sequence is: small wire get energised, which power the solenoid, which engage the gear. Once the gear is in, the copper disk that is part of that "switch" make the contact and the starter turn.
The small wire come from the ignition key switch, then go to the transmission shift interlock switch (that prevent a car from starting when in gear) or to the clutch pedal for manual transmission. That wire can also be cut and a relay inserted there for anti-theif protection...
So you have 2 power path and a few mechanical devices.
Check for the voltages first. It will help to understand stuff.