68 Radio Wiring
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Safety Car
Joined: Jul 1999
Posts: 4,430
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From: Harrisonburg, VA
68 Radio Wiring
Our 68 did not have a radio (it originally came with one, it was just missing when we bought the car).
We got a radio yesterday, but couldn't get it working.
The instructions said to connect the red wire from the radio to the red wire from the ignition, the yellow wire from the radio to the yellow wire from the wiring harness, and the black wire from the radio to ground.
Well, there was a red and a yellow wire both coming from the wire pack behind the guage area that were taped off at the ends and not leading anywhere. I assumed these were the correct wires, so I connected them as the instructions stated. Turned the key on, but no power to the radio. :(
So, I need to figure out if these are the correct wires, and if so, if they are getting power. I have a digital multimeter, but I'm not sure what I should be setting it to, in order to properly testing the wires.
It is similar to this unit:
And it has a red testing line and a black testing line.
I assume the black testing line goes in the "COM" hole on the multimeter.
I need to know which hole I should plug the red wire into and what I should set the mutlimeter to read.
After I know that, I assume I should then hold the black tester on a ground and hold the red tester on the red wire from the ignition wire pack and turn the key from off to on and see if the setting changes (and what would a "good" reading be?).
Thanks, and sorry if this is a stupid question but I'm not real familiar with electronics, as you can guess! :bb
[Modified by Vettastic, 9:34 AM 4/29/2004]
We got a radio yesterday, but couldn't get it working.
The instructions said to connect the red wire from the radio to the red wire from the ignition, the yellow wire from the radio to the yellow wire from the wiring harness, and the black wire from the radio to ground.
Well, there was a red and a yellow wire both coming from the wire pack behind the guage area that were taped off at the ends and not leading anywhere. I assumed these were the correct wires, so I connected them as the instructions stated. Turned the key on, but no power to the radio. :(
So, I need to figure out if these are the correct wires, and if so, if they are getting power. I have a digital multimeter, but I'm not sure what I should be setting it to, in order to properly testing the wires.
It is similar to this unit:
And it has a red testing line and a black testing line.
I assume the black testing line goes in the "COM" hole on the multimeter.
I need to know which hole I should plug the red wire into and what I should set the mutlimeter to read.
After I know that, I assume I should then hold the black tester on a ground and hold the red tester on the red wire from the ignition wire pack and turn the key from off to on and see if the setting changes (and what would a "good" reading be?).
Thanks, and sorry if this is a stupid question but I'm not real familiar with electronics, as you can guess! :bb
[Modified by Vettastic, 9:34 AM 4/29/2004]
Race Director
Joined: Nov 1999
Posts: 10,643
Likes: 8
From: Foxfield CO 1970 Convertible
Re: 68 Radio Wiring (Vettastic)
OK - here's what I'd do.
First, make sure the battery in the meter is good. These are usually a 9-volt battery.
Put the Black lead in Com.
The red lead in Volt/Ohm (the hole in the center).
Turn the dial to the white 20 on the V side. This is DC Voltage. (The other V is DC Current - the blue V settings.) Since the car battery is 12, you want to set to the next level higher than 12. You could use 200, but the reading won't be as accurate.
Now, ground the black wire on the frame somewhere and hook the red to the red lead to the red wire coming from the wire pack. When you turn on the key, the meter should read somewhere near 12 - it might be somewhat higher or lower say 11 - 13 volts. If nothing happens, try the yellow. I personally think red is used universally for positive power.
You can test using the meter on a light bulb socket in the car - possibly one of the interior lights that come on when the door is opened. The meter should give you a reading when you let out the door switch pins and go back to zero when you push the pin in or close the door.
You can also test the fuse block. Put the black on ground, and touch various places on the fuse block. When you hit a hot lead, the meter will jump to 12.
When you are done testing, remove the leads before rotating the **** on the meter to the "off" position, otherwise you might select a range that is too low for 12 volts and burn out a fuse or break the meter.
You can check to see if a wire is broken with the leads in the same holes. Select one of the ranges in blue with the K under it, say 20k. The meter should read 20 (20,000 ohms). If you touch the tips of the two leads together, the reading should drop to zero, which means there is no resistance between the leads (good contact). Now to check a wire, connect one lead to one end of the wire and the other lead to the other end of the wire. If the wire is good, the reading should drop to zero. If there is a bad connection (possible rust or corrosion) the reading will lower somewhat but will not go to zero. Experiment with the various k settings (blue k ohm letters) to see which is best.
Disclaimer: I'm more used to my own meter which is somewhat different, so don't try to sue if it doesn't work exactly as I described...For instance, when checking continuity in a wire or circuit, the meter may start at zero and go up to 20k instead of the way I described. My meter says "infinite" when the wires are not connected and moves to zero when they are connected. Your manual should clear this up. Either way, it's easy to experiment with resistance readings (ohms).
Hope this helps.
Good luck :)
[Modified by Z-man, 1:47 PM 4/29/2004]
First, make sure the battery in the meter is good. These are usually a 9-volt battery.
Put the Black lead in Com.
The red lead in Volt/Ohm (the hole in the center).
Turn the dial to the white 20 on the V side. This is DC Voltage. (The other V is DC Current - the blue V settings.) Since the car battery is 12, you want to set to the next level higher than 12. You could use 200, but the reading won't be as accurate.
Now, ground the black wire on the frame somewhere and hook the red to the red lead to the red wire coming from the wire pack. When you turn on the key, the meter should read somewhere near 12 - it might be somewhat higher or lower say 11 - 13 volts. If nothing happens, try the yellow. I personally think red is used universally for positive power.
You can test using the meter on a light bulb socket in the car - possibly one of the interior lights that come on when the door is opened. The meter should give you a reading when you let out the door switch pins and go back to zero when you push the pin in or close the door.
You can also test the fuse block. Put the black on ground, and touch various places on the fuse block. When you hit a hot lead, the meter will jump to 12.
When you are done testing, remove the leads before rotating the **** on the meter to the "off" position, otherwise you might select a range that is too low for 12 volts and burn out a fuse or break the meter.
You can check to see if a wire is broken with the leads in the same holes. Select one of the ranges in blue with the K under it, say 20k. The meter should read 20 (20,000 ohms). If you touch the tips of the two leads together, the reading should drop to zero, which means there is no resistance between the leads (good contact). Now to check a wire, connect one lead to one end of the wire and the other lead to the other end of the wire. If the wire is good, the reading should drop to zero. If there is a bad connection (possible rust or corrosion) the reading will lower somewhat but will not go to zero. Experiment with the various k settings (blue k ohm letters) to see which is best.
Disclaimer: I'm more used to my own meter which is somewhat different, so don't try to sue if it doesn't work exactly as I described...For instance, when checking continuity in a wire or circuit, the meter may start at zero and go up to 20k instead of the way I described. My meter says "infinite" when the wires are not connected and moves to zero when they are connected. Your manual should clear this up. Either way, it's easy to experiment with resistance readings (ohms).
Hope this helps.
Good luck :)
[Modified by Z-man, 1:47 PM 4/29/2004]
