An ignition/starting issue on my 1973 Plymouth Fury automatic

[Binky1945]

Hello, I am Jim Dent. I haven't been on here for quite some time but I find myself needing learned assistance on an ignition/starting issue on my 1973 Plymouth Fury. I cannot get the motor to start. It turns over just fine but the electrical connection that supplys the spark is not there. The car has had a myriad of electrical problems in the past but I was able to work all of those out. This is the first time I have experienced this problem I even have one of the fancy laminated wiring schematic sheets and everything appears to be connected properly connected. However, it appears that somewhere along my meddling I have lost a hot or ground connection in one of the wires that run from the ignition switch to the starter solonoid which allows the car to run. The original wire that seems to be at the root of the problem is color coded YELLOW running from the starter solonoid to the ignition switch. Somehow I lost continuity thru this wire (heck, I even lost that end of the damn wire) and I then ran a replacement wire from the same post on the solonoid to the end of the yellow wire that was still attached to the ignition switch. What I really need is a simple (hand-drawn even) drawing of what pertinent wires come from where, going to where-ever in the start circuit of the wiring, just in case I am indeed to ignorant to correctly read and follow the lines on the printed schematic. Is it possible to get some help from one of you guys along these lines? I can be contacted at [email protected] for e-mailed drawings or properly chastized for being such a damn dummy at 859 575.4444 Thank you, Jim

 

[Big_John]

Hello, I am Jim Dent. I haven't been on here for quite some time but I find myself needing learned assistance on an ignition/starting issue on my 1973 Plymouth Fury. I cannot get the motor to start. It turns over just fine but the electrical connection that supplys the spark is not there. The car has had a myriad of electrical problems in the past but I was able to work all of those out. This is the first time I have experienced this problem I even have one of the fancy laminated wiring schematic sheets and everything appears to be connected properly connected. However, it appears that somewhere along my meddling I have lost a hot or ground connection in one of the wires that run from the ignition switch to the starter solonoid which allows the car to run. The original wire that seems to be at the root of the problem is color coded YELLOW running from the starter solonoid to the ignition switch. Somehow I lost continuity thru this wire (heck, I even lost that end of the damn wire) and I then ran a replacement wire from the same post on the solonoid to the end of the yellow wire that was still attached to the ignition switch. What I really need is a simple (hand-drawn even) drawing of what pertinent wires come from where, going to where-ever in the start circuit of the wiring, just in case I am indeed to ignorant to correctly read and follow the lines on the printed schematic. Is it possible to get some help from one of you guys along these lines? I can be contacted at [email protected] for e-mailed drawings or properly chastized for being such a damn dummy at 859 575.4444 Thank you, Jim

The best place for a wiring diagram is the factory service manual and while you can't get a '73 Plymouth version to download for free, they have a '73 Dodge version that will be virtually identical for your present needs. Service Manuals – MyMopar

That said... By "not starting", you are meaning the engine isn't turning over... Correct?

The yellow wire goes to the neutral safety switch. First is always to check if the car is in park or neutral. (You'd be surprised at how many times this happens LOL) It returns ground from the switch and the relay won't work unless that terminal is grounded. So the best way to check that is with meter or test light. Hook one end to positive and the other to the wire and you should be able to see if the switch and wire is good. While I don't recommend this as a solution for anything more than trying it.... You can just ground that yellow wire terminal and try it. It is called a "safety switch" for a reason and I only suggest that to find or isolate the problem. Many cars have been put through garage walls when that neutral switch is bypassed.

Next culprit is the relay itself. Lot's of failures on that over the years. The way to check this, and starter operation is to take an old screwdriver and jump between the terminal the big red wire is on and the terminal the small red wire is on. No need to remove wires. If the starter spins over, then it's either the relay (most likely) or the feed from your ignition switch.

Nobody is going to chastise you... We weren't born knowing everything and it's all stuff we've learned one way or another... Usually the hard way. Often with cold and snow involved LOL.

 

[D Cluley]

Looks like it turns over, but no spark, correct?

If it is turning over, then you don't have a problem with the yellow wire or the starter relay.

The wires that power the coil should be dark blue and brown.

The ignition switch gets power in from the battery through the red wire.

With the key in the run position, that 12 volts goes out through the dark blue wire to the ballast resistor (should be a white ceramic rectangle bolted to the firewall or fender underneath the hood) Something less than 12 volts comes out the other end of the resistor and through the brown wire to the coil.

With the key in the start position (the spring loaded twist to actually start the engine) the 12 volts goes out through the brown wire and straight to the coil bypassing the resistor (so you get a good hot spark to start the engine even when the starter motor is drawing a lot of current from the battery)

It is not uncommon for the resistors to go bad. At that point the car will seem like it is starting when the key is turned all the way to start but will die as soon as you let the key spring back to run.

 

[Binky1945]

The best place for a wiring diagram is the factory service manual and while you can't get a '73 Plymouth version to download for free, they have a '73 Dodge version that will be virtually identical for your present needs. Service Manuals – MyMopar

That said... By "not starting", you are meaning the engine isn't turning over... Correct?

The yellow wire goes to the neutral safety switch. First is always to check if the car is in park or neutral. (You'd be surprised at how many times this happens LOL) It returns ground from the switch and the relay won't work unless that terminal is grounded. So the best way to check that is with meter or test light. Hook one end to positive and the other to the wire and you should be able to see if the switch and wire is good. While I don't recommend this as a solution for anything more than trying it.... You can just ground that yellow wire terminal and try it. It is called a "safety switch" for a reason and I only suggest that to find or isolate the problem. Many cars have been put through garage walls when that neutral switch is bypassed.

Next culprit is the relay itself. Lot's of failures on that over the years. The way to check this, and starter operation is to take an old screwdriver and jump between the terminal the big red wire is on and the terminal the small red wire is on. No need to remove wires. If the starter spins over, then it's either the relay (most likely) or the feed from your ignition switch.

Nobody is going to chastise you... We weren't born knowing everything and it's all stuff we've learned one way or another... Usually the hard way. Often with cold and snow involved LOL.

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[Binky1945]

Thank you for your prompt report Big John I had a much more knowledgable friend come over for a quick look see and he did find the problem to be with the way my son had reconnected the yellow wire which did result in everything under the hood going dead because of no power fed to them It was basically the same way you mentally trouble shot my verbal complaint. I most certainly do appreciate you help and assistance in aiding me with this complaint. I hope I can return the favor some way some day. Thank you again, Jim