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65 Corvette ignition switch

Bubber

New member
Joined
Jul 5, 2012
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4
Location
Clermont, Ga
Corvette
1970 convertible, 1998 Pace car
I have a 65 Vette with a 396 engine. If I hold the key on "start" it seems to run ok but if I let go of the key the car just dies. Does this sound like the ignition switch ? Any other suggestions ??
Thanks in advance
 

Hib Halverson

Technical Writer for Internet & Print Media
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Jan 10, 2001
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13,453
Location
CenCoast CA
Corvette
71 04 12 19
When you hold it on "Start" is the starter motor also running?
 

Bubber

New member
Joined
Jul 5, 2012
Messages
4
Location
Clermont, Ga
Corvette
1970 convertible, 1998 Pace car
No .. I only drove it into the garage. Scared to go any further
 

Tom Bryant

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Administrator
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Nov 9, 2000
Messages
7,195
Location
Edgerton, Ohio, United States
Corvette
1959 black 270hp (9/2/69) 1981 Beige L81(10/20/80)
I moved this thread from the For Sale/Wanted forum to the C1/C2 General and Technical Forum.

Tom
 

Tom Bryant

Well-known member
Administrator
Joined
Nov 9, 2000
Messages
7,195
Location
Edgerton, Ohio, United States
Corvette
1959 black 270hp (9/2/69) 1981 Beige L81(10/20/80)
Let's start with the ignition switch test first without any disassembly. Turn the switch to the "on" position and use your test light to check for power at the ballast resistor on the firewall next to the coil. Check at the harness side of the resistor and not the coil side. If your test light comes on your switch is good. If not you have a problem somewhere between the switch and the coil. If your test light comes on also use a volt meter to check for 12v at the harness side of the resistor and a reduced voltage at the coil side. Also check for the same reduced voltage at the "+" terminal on the coil.

On a points ignition system the wire in the above test is the wire from the ignition switch to the ballast resistor that supplies power to the coil for power when the switch is in the "on" position. The resistor knocks the voltage down to around 9.5 volts because a full 12 volts all the time will burn up the points quickly. There is another wire that runs from the starter solenoid "R" terminal to the coil "+" terminal that supplies a full 12 volts to the ignition for starting only when the ignition switch is in the "start" position only. As soon as you allow the switch to return to the "on" position this wire goes dead and the ignition is running off of the ballast resistor wire.

So when you are holding the switch in the "start" position to keep the engine running you are using the solenoid to coil wire for power. Your starter motor will be running as long as you hold the switch in the "start" position. There is no way for it to turn off except for releasing the switch to the "on" position or starter failure.

Since it will not stay running in the on position there has to be an interruption in the circuit from the ignition switch to the coil. If you have power to the resistor let's do a second check on the ballast resistor. You can remove the wire from one side and install it on the other side effectively putting all resistor wires on the same terminal to bypass the resistor. Now you will have a full 12 volts to the coil. Start the engine and see if it runs in the "on" position. If it does you have a bad resistor. This is ok to do for a test but don't operate the car with this jump in place because it will burn up your points quickly. Return resistor wires to their correct terminals.

If it's still not running in the "on" position make up a jumper wire with alligator clips so it is quickly installed and removed and jump from the battery positive terminal to the side of the ballast resistor from the harness and not the coil side. This essentially turns on the ignition and you should be able to start the car with the switch and it should run in the "on" position since you have bypassed the ignition switch. If it starts and runs, and it should, turn off the engine and disconnect the jumper and trace the wire from the resistor back to the firewall bulkhead connector checking for damage. Corrosion is common in the bulkhead connector so remove it and check that it is clean inside. If not clean the connections. If it's really bad there is a bulkhead connector repair kit available from ZIP and others. Now that the bulkhead connector is apart use your ohm meter and check the wire from the connector to the ballast resistor for continuity. If it's good unplug the connector from the ignition switch and check the wire from the bulkhead connector to the ignition switch for continuity. Check the connector for corrosion or damage. With everything back together except for the switch connector check continuity from the ignition switch plug to the end of the wire that connects to the "+" terminal on the coil.

If it's ok you have a good circuit from the switch to the coil so so it should start and run as normal. If it still won't run in the "on" position do an isolated ignition switch test. Plug in the ignition switch and run a test light to a good ground. Insert the light probe into the back of the switch connector to contact the ignition terminal and turn the switch to the "on" position. If it lights up your switch is good. If not, bad switch.
 

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