License plate light not working - Impala Tech
Electrical & Wiring Troubleshooting electrical problems

 
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post #1 of 5 (permalink) Old 12-16-2017, 11:59 AM Thread Starter
 
 
Join Date: Jun 2011
Location: Phoenix
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License plate light not working

My license plate light on my '67 isn't working and I cannot seem to figure out why. Using a test light, there is power to the wire and contact point at the end of the wire (inside the socket). When I put the new lightbulb in, there is power to the entire socket but the bulb doe not illuminate. My multimeter is broken so I am not sure how many volts I have. All of the taillights and everything else eclectically works. Any suggestions?
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post #2 of 5 (permalink) Old 12-16-2017, 01:16 PM
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Quote:
Originally Posted by QuasarZ View Post
My license plate light on my '67 isn't working and I cannot seem to figure out why. Using a test light, there is power to the wire and contact point at the end of the wire (inside the socket). When I put the new lightbulb in, there is power to the entire socket but the bulb doe not illuminate. My multimeter is broken so I am not sure how many volts I have. All of the taillights and everything else eclectically works. Any suggestions?
Power is half of the circuit. Without a ground it won't work.

Big Dave
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post #3 of 5 (permalink) Old 12-16-2017, 09:50 PM Thread Starter
 
 
Join Date: Jun 2011
Location: Phoenix
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Thanks for the reply Big Dave. Even when it is fastened to the bumper it doesn't work. Is there supposed to be a ground from the bumper to the frame? This seems simple yet I cannot get it to work correctly.
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post #4 of 5 (permalink) Old 12-16-2017, 10:08 PM
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The socket grounds the bulb, the lamp assembly grounds the socket, the cove panel grounds the lamp assembly, and the cove panel is grounded by spot welds that hold the body together. The body is grounded at the fire wall bu three flat grounding straps that connect the body to the motor, the motor is grounded by way of the negative battery cable.

If there is corrosion, rust, or a missing connecting link your tail lamp or license plate lamp it will not light up. After fifty years of exposure to the weather I can almost guarantee it is a bad ground, somewhere.

To find bad grounds in my shop I used a ten gauge twenty five foot long wire that had an large battery terminal size alligator clamp at one end and a smaller alligator clip at the other, that I used to touch things or attach the wire with the clip to a part to assure that I got a good ground back to the battery. If it lit up or other wise worked I knew I had a bad ground. It was a just matter of checking the connections back to the battery to find out were the ground was bad from there.

Big Dave
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post #5 of 5 (permalink) Old 12-29-2017, 11:44 PM Thread Starter
 
 
Join Date: Jun 2011
Location: Phoenix
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It turns out the socket was not grounded to the metal lamp assembly. A couple of rotations of the socket and whatever corrosion was present disintegrated and the light now works for the first time in years. The little victories in these old cars make me happy!
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