1937 Plymouth 4 Door Sedan


Asked by Sep 13, 2010 at 12:55 PM

Question type: Maintenance & Repair

Trying to find wiring diagrams...or even pictures would do probably. We get power INTO the coil but not coming out. Fog lights were added at some point and motor was changed to an alternator from the original generator. So there is some "random" wires in there that we don't want to mess too much with until we know exactly what is what. Suggestions? Even pointing us to more sites with forums or something would be a super start!!

5 Answers


The original system was 6V. Most all alternators output 12V. Has the car been converted to 12V operation? Wiring in these older cars really is simple. I have rewired a 1941 Ford convertible and the owner was very satisfied with the effort. If the system was changed to 12V, you have a couple of choices to consider for the coil and ignition. If the coil is running off 12V, insure the coil is a 12V coil with a dropping resistor that can be bypassed during starting. If it is a 6V ignition driven system, insure that the power supply that drops the voltage from 12V to 6V is not cutting out during starting.


Thanks for the quick reply!! The generator was swapped for an alternator years ago by Keith's dad. We are sure the alternator is 12V since none of us have ever heard of a 6V alternator. But....i still question that a bit since the solenoid we replaced said 6V on it. (brand new battery in it too & plugs) We now have a new 12V solenoid & coil and had the starter rebuilt. After putting in the starter we got more action out of the engine. But then the coil seemed to be giving us issues. We arent sure if we blew the coil or what happened. We got a new coil and now we have power going into the coil but none coming out. There is a few messed up wires in there ... fog lights were added at some point and we're not sure where a few of the loose wires go. Some live some dead. Even tracing them isnt helping due to the modifications that may or may not have been done. We're being extra careful so we don't mess something up and make it worse.


You still haven't told me if the battery is 6V or 12V. If it is a 12V, then did you put the resistor in series with the 12V coil? This is a ceramic resistor that limits current to the coil to prevent it from burning out. Please be sure the coil is correctly wired since you will not get adequate spark if wired in reverse. Typically a 12V coil with a negative ground system will have the minus terminal connected to the distributor, and the plus connected to the dropping resistor. It's been 40+ years since I last worked on a 37 Plymouth coupe.


12V battery .. sorry ... just assumed that wuz standard these days from what i heard mentioned around the car hehehe i'm new guy on these kinds of projects ... i handle the computer side of things mainly :P but i'm learnin FAST ;) hehehe what if we skipped the coil and went right to the distributor? would that even be a valid troubleshooting step to try and see where we're losing the juice? positive is good into the coil...tester lights up...but not on negative ... i'm gonna take some pics tonite if i can and post them in here to show the parts n wiring we have goin so far... that should help some hehe

1 people found this helpful.

Remember, the points are closed most of the time, so they will basically ground that side of the coil. You really need to put a meter (needle type best, not digital) and you should be able to see the needle swing back and forth as you are turning the engine over. The points only open to fire a plug and stay open for a fraction of the time. This is called dwell and is specified for the Kettering ignition systems (non electronic with points and coil). Put the voltmeter on a scale that can handle about 20V when you attempt this measurement.

2 people found this helpful.

Your Answer:


Looking for a Used Plymouth in your area?

CarGurus has 552 nationwide Plymouth listings starting at $22,000.


Plymouth Experts

  • #1
    Tom Demyan
  • #2
  • #3
View All

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.