1972 350 coil wiring ....?
Le Mans Master
Joined: Aug 2006
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Very helpful picture.
When I was working on mine and needed to figure out which went were I used a test light.
With the two wires by the starter disconnected I ran a long wire to one and connected the other end to a test light that I could see over the dash.
One would be hot with ignition on. One would only be hot when attempting to start then would turn off when I released the key.
With the two wires by the starter disconnected I ran a long wire to one and connected the other end to a test light that I could see over the dash.
One would be hot with ignition on. One would only be hot when attempting to start then would turn off when I released the key.
When the starter is ON a disc (inside the solenoid) sends 12 volts UP the (yellow) wire from the "R: terminal.
When the key is in RUN the YELLOW wire sends 12 volts DOWN to the solenoid (because the BLACK- PINK and the YELLOW are connected at the coil) but the DISC is no longer engaged.
The YELLOW wire is LIVE but not now connected to any circuit.
Le Mans Master
Joined: Aug 2006
Posts: 7,427
Likes: 1,560
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
I was testing last night trying to figure out where the black wire that is now connected at the coil + side ran to....Hooked up the multimeter set to continuity/beep mode took the wire off the coil and clipped one end of the meter to it then started to try wires on the starter but I didn't even make it that far...No matter where I touched it indicated continuity, this is with the negative cable disconnected from the battery. That doesn't seem right to me.
Thank Ya'll for the post above, I'll do more testing tonight.
Brian
Thank Ya'll for the post above, I'll do more testing tonight.
Brian
Le Mans Master
Joined: Jul 2006
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From: charlotte north carolina
Your meter itself is supplying the current to complete the continuity test. The points are closed and anywhere that you touch completes the circuit thru the coil, points and anywhere on the car. Disconnect the capacitor in the distributor-remove it from the hold down clamp and make sure it doesn't touch anything. Connect battery and turn ignition to "run". Test voltage from + to - side of coil. Then test from + coil to engine ground. Both should be exactly the same and be about 11 volts. If there's a difference, there is a bad connection in the distributor or the points are bad. If it reads 12 volts, you do not have a resistor in the circuit.
Thread Starter
Drifting
Joined: Apr 2010
Posts: 1,857
Likes: 332
From: Cartersville GA
First thing I did was connect the black and red wire into one connection and put it back on the coil.
I took the capacitor out of the distributor but kept the wire from the - side of the coil hooked to the points....With points closed I get 6.4 volts reading from + side to - side of the coil...and 6.4 volts reading from + side of coil to body ground....With the points open I get 0 volts from + side of coil to - side and 12.54 volts from + side to engine ground.
Brian
I took the capacitor out of the distributor but kept the wire from the - side of the coil hooked to the points....With points closed I get 6.4 volts reading from + side to - side of the coil...and 6.4 volts reading from + side of coil to body ground....With the points open I get 0 volts from + side of coil to - side and 12.54 volts from + side to engine ground.
Brian
Le Mans Master
Joined: Jul 2006
Posts: 8,117
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From: charlotte north carolina
That proves that the coil wire has 12v. With the points open, there is an open circuit and your zero volt reading across the coil is correct. The 6.4 volt reading seems to be the problem. With the points closed and the ignition switch on "run", there should be about 11 volts from the + to the - terminals of the coil. Either the coil is bad, the points are burned or there is a bad connection in the circuit.
As a side note, it's important to measure the voltages with the points closed. If they are open, the meter will act to complete the circuit to ground, and since the internal resistance of the meter is several thousand ohms, the meter itself will act as the largest voltage drop. This will lead to confusing readings.
As a side note, it's important to measure the voltages with the points closed. If they are open, the meter will act to complete the circuit to ground, and since the internal resistance of the meter is several thousand ohms, the meter itself will act as the largest voltage drop. This will lead to confusing readings.
Thread Starter
Drifting
Joined: Apr 2010
Posts: 1,857
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From: Cartersville GA
I'll pick up a new set of points tomorrow and report back on the readings.
I don't quite understand how the 2 wires work going to the + side of the coil....Forget what the stock color of wires are supposed to be....I have a single black wire running to the + side of the coil and it ran down the road just fine with just this wire attached....The red wire wasn't attached at all....If the red wire was in fact the resistance wire does it take over for the black wire and provide 11 or so volts or does it reduce the 12.5 volts being provided by the black wire....?
The points may be burnt up at this point which would explain my problem with the car dieing at a stoplight which brought this whole trouble shooting episode up in the first place...Fuel filter was stopped up and might also be the cause. I haven't tried to run the car down the road yet.
Thank Ya'll for the help...
Brian
I don't quite understand how the 2 wires work going to the + side of the coil....Forget what the stock color of wires are supposed to be....I have a single black wire running to the + side of the coil and it ran down the road just fine with just this wire attached....The red wire wasn't attached at all....If the red wire was in fact the resistance wire does it take over for the black wire and provide 11 or so volts or does it reduce the 12.5 volts being provided by the black wire....?
The points may be burnt up at this point which would explain my problem with the car dieing at a stoplight which brought this whole trouble shooting episode up in the first place...Fuel filter was stopped up and might also be the cause. I haven't tried to run the car down the road yet.
Thank Ya'll for the help...
Brian
Thread Starter
Drifting
Joined: Apr 2010
Posts: 1,857
Likes: 332
From: Cartersville GA
Finally installed new points but the readings didn't change much, with the the capacitor still out of the distributor...
With points closed I get 6.21 volts reading from + side to - side of the coil...and 6.88 volts reading from + side of coil to body ground....With the points open I get 0 volts from + side of coil to - side and 12.54 volts from + side to engine ground.
Looks like I have another issue besides the points.
The next step I'm going to take is find out where the black wire is attached to.
Any other ideas....?
Brian
With points closed I get 6.21 volts reading from + side to - side of the coil...and 6.88 volts reading from + side of coil to body ground....With the points open I get 0 volts from + side of coil to - side and 12.54 volts from + side to engine ground.
Looks like I have another issue besides the points.
The next step I'm going to take is find out where the black wire is attached to.
Any other ideas....?
Brian
Tech Contributor
Joined: Jun 2004
Posts: 20,910
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Finally installed new points but the readings didn't change much, with the the capacitor still out of the distributor...
With points closed I get 6.21 volts reading from + side to - side of the coil...and 6.88 volts reading from + side of coil to body ground....With the points open I get 0 volts from + side of coil to - side and 12.54 volts from + side to engine ground.
Looks like I have another issue besides the points.
The next step I'm going to take is find out where the black wire is attached to.
Any other ideas....?
Brian
With points closed I get 6.21 volts reading from + side to - side of the coil...and 6.88 volts reading from + side of coil to body ground....With the points open I get 0 volts from + side of coil to - side and 12.54 volts from + side to engine ground.
Looks like I have another issue besides the points.
The next step I'm going to take is find out where the black wire is attached to.
Any other ideas....?
Brian
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Thread Starter
Drifting
Joined: Apr 2010
Posts: 1,857
Likes: 332
From: Cartersville GA
I'll put her back together tomorrow, check the dwell and set the timing and she how she runs. I'll keep an extra set of points and tools to do the job in the car from now on.
Brian
Brian
Racer
Joined: Aug 2008
Posts: 413
Likes: 22
From: Justin TX
Peterbuilt it spot on, here is the diagram from my 69 (same as the 72 he posted), the yellow wire from the solenoid provides full 12 volts to coil only when the key is in start position. The black/pink wire is the ballast wire, it provides the lower voltage and has power anytime the key is in the on or start position. Both should be connected to the + on the coil. Sounds like the only wire hooked up on your car is the ballast wire, which means you do not get full voltage during starting which may cause hard starts.
If yours is not wired this way someone has made modifications that need to be corrected.
Stranger things have happened.
Thread Starter
Drifting
Joined: Apr 2010
Posts: 1,857
Likes: 332
From: Cartersville GA
The black wire is not original, I know it has 12 volts in both run and start mode or it wouldn't have even ran with just it hooked up. I need to trace it down. The red wire I believe is original and I think is the ballast wire.
Guess I still got issues to work out.
Brian
Guess I still got issues to work out.
Brian
Thread Starter
Drifting
Joined: Apr 2010
Posts: 1,857
Likes: 332
From: Cartersville GA
Well I got everything back together today....Dwell set at 30. I didn't take it for a test drive because it was too late and I didn't want to take a chance on another break down. I did not get to set the timing, I don't have a light yet.
I know the volts won't read right with the motor running but I have read that somewhere around 9 volts is close....Well I'm around 4.8.
I didn't get a chance to trace where the black and red wire run to...Maybe tomorrow.
On a good note the the fuel line doesn't leak nor does the new heater hose fitting I installed....Now there is no interference between the fuel line and heater hose.
Brian
I know the volts won't read right with the motor running but I have read that somewhere around 9 volts is close....Well I'm around 4.8.
I didn't get a chance to trace where the black and red wire run to...Maybe tomorrow.
On a good note the the fuel line doesn't leak nor does the new heater hose fitting I installed....Now there is no interference between the fuel line and heater hose.
Brian