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George H.
George H., Technician
Category: Classic Car
Satisfied Customers: 18389
Experience:  Old enough to have worked on them when they were new
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Im having problems figuring out why I can not start my 67

Customer Question

Im having problems figuring out why I can not start my 67 mustang. When I turn the ignition on I here a click only. I have change the starter relay three times sio I know it is not this. When I take a screw drive and connect the positive terminal from the battery to the S terminal I can turn over the engine and start the car. What else is causing this problem??
Submitted: 1 year ago.
Category: Classic Car
Expert:  George H. replied 1 year ago.

Hello I will help you with your question,

Do you have a voltmeter to check the S terminal while you turn the key to the start position? See if you really have 12 volts there. I think you will find something less than 6 which means you have a voltage drop. You will need to check the voltage to the switch with the switch held in the start position for a second, if you have 12 volts in but much less out replace the ignition switch. if you still have low voltage in check the fuse block to see if the fuses are corroded.

You are doing the job of the switch with the screwdriver so if the small wire does not have the same 12 volts you have at the battery post on the solenoid then you will not close the solenoid to give power to the starter.

Let me know how I can help

Thank you

Customer: replied 1 year ago.
I have 12 volts on the I terminal when the ignition is turned on. When I fully turn the ignition to start I have no volt reading on the S terminal wire.
Customer: replied 1 year ago.
I also noticed. When the ignition is turned on I have 12 volts at the I terminal. No volts to the S terminal. When ignition is turned to Crank I have no volts to the S terminal. I still have volts to the I terminal.
Expert:  George H. replied 1 year ago.

The I terminal is fed from another source, you will need to check at the ignition switch to see if the problem is in the switch or at the fuse block.

The key here is you have to have current flowing in the circuit when you check so to avoid burning up a solenoid do you have a headlamp bulb you can connect to the end of the wire at the S terminal and then on to a ground while testing?

I am sorry but I am unable to speak on the phone, we can continue here though.

Customer: replied 1 year ago.
I have a test lamp that I use. When connected to the I terminal I have power when I turn on the ignition and stays on when ignition is cranked.
When I test the S terminal the same way. I have no power.
Expert:  George H. replied 1 year ago.

The test lamp draws a couple amps of current at least? That is required to get accurate measurements.

Disconnect the S terminal wire from the solenoid and measure at the ignition switch. If the s wire has 0 or low volts when you turn the switch to the start position move your meter lead to the feed for the switch and repeat the measurement. If you have 12 volts in at all times but the S wire drops to low volts replace the ignition switch. If the feed wire to switch drops as well in the start position then you need to check at the fuse block for corrosion.

Let me know if that is clear how to run the test

Thank you

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