ignition starting problem

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68 A

68 A

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hi,

I took the ignition off my dart to fix some leaks associated with the intake manifold. I put it back on and now i am having an issue with it starting.

first some info:

- I have a Davis Unified Ignition Chrysler Tri-power system (electronic distributor, no ballast resistor)

- With the ignition switch "on" there is about 12 volts on both the positive and negative sides of the coil, as well as the wire to the distributor

- With the ignitioin switch in the "start" position, there is NO power to the coil.

- It will start sometimes, but it starts when i let off of the key, because the engine is still spinning and it gets power once the ignition is back to the "on" position.

- when i first installed the ignition, i got info from here on how to bypass the ballast resistor and the old mopar electronic ignition module.


I wanted to add some edited wiring diagrams to show what i did, but paint won't read the file of the diagram i have. so i will attatch a stock diagram and explain best i can of what i did.


- The stock diagram is set up for points and condensor, so it never had the electronic module i removed in it, but i have traced wires and looked at the diagram and they are the same on the diagram as on my car.

What i origionally did:

- i cut the ballast resistor out, and connected
DK Blue-Tr, DK Blue, and the wire coming out of the alternator regulator that the color is not labled, but appears to be another DK Blue, or Violet.

These were then connected to Brown, which was connected to the DK Blue that feeds the positive side of the coil

It started and ran fine like this, although the wiring I did was in a hurry and poorly done.

- having some trouble getting spark yesterday morning, i took this connection apart and was going to rewire it.

- The best way i thought i could rewire it was to put a connector with a loop on the end of all 5 wires and put a bolt through them to connect them.

- So now all 5 wires are connect together in the same spot.

- I remembered tonight that i read somewhere (don't remember where) that with the origional system when the ignition switch is "on" the power went through the resistor to cut it to 12 volts, but when it was in "start" it bypassed the resistor and gave the coil full voltage for starting.

- Maybe what i changed with my wiring did something and that is why i don't have power when the switch is at "start", but i do have power when it is "on"??

I am still learning about these electrical systems and the most experience i have is with this car. I know someone knows these better than i do!

Sorry about the post being long, but i wanted to be good and thorough. however i'm sure i missed something.

Here is the wiring diagram:

http://www.mymopar.com/downloads/1970/70DartA.JPG
http://www.mymopar.com/downloads/1970/70DartB.JPG

Thanks,

Steve
 
Steve it sounds to me like the mod you did to bypass the ballast resistor is correct. That should give you full 12 volts anytime the key is on or in the crank position. It sounds like the classic case of the ignition switch has gone bad and not providing power when your cranking but since you bypassed the ballast it shouldn't matter. The only test I can think of is to hook up your volt meter to the B+ going to the dist. and monitor it while your cranking it over an see if in fact it is getting voltage then.
 
Thanks fishy,

actually i think you told me how to wire it to begin with about a year ago.

hopefully i'll have enough time and my roommate will be around tommorow night to test the power. Last night before posting i tested the positive side of the coil, with the ignition on it was 12V, cranking, it dropped to 0.3, then back to on, 12V.

I only tested the positive side though. I do have a new ignition switch (i assume you mean the unit the key slides into, i dont remember seeing anywher to hook wires onto it and have never looked at one installed) so i could try to figure out how to switch that just as a back up check.

When i read these wiring diagrams I have difficulty figuring out which direction power is going with some systems. Obviously it goes from the battery or alternator to a switch and then to lights/ignition/accessory/etc...,
but i should understand it better with some time

Thanks!

STEve
 
Yeah it takes awhile to get the hang of reading those old schematics. Even though there's less stuff than a new car has they can be a chore.

Yes I did mean the part the key slides into. If your voltage dropped to .3 volt when cranking that's probably your problem. I don't know positively since I've never had to work on my key switch section but I believe it may just have a big slide on multi terminal connector so changing it is a snap.

It should have at least 11 volts on the coil positive terminal during cranking. It would have full battery voltage but the starter draws alot so that pulls it down some.

The positive side of the coil is the main thing you need to check anyway. The negative side only goes low when the pickup sends a signal to to make it fire so concentrate on getting B+ to the pos. side when cranking.

Good luck.
 
and now i can start to get working on my car again after having to get my appendix out.

so after finding out it is very difficult to change the ignition switch and that i only have the key cylinder. I do not currently have the required pieces.

However, i tried tonight and i do have voltage now when it is cranking. And i got the car to run. Thinking back, i have had times before when the car wouldn't start(probably 3 or 4, but never checked any voltages), but would start the next day, or a week or so later. However i didn't do anything to it between these times. I may have a loose wire or something, (probably the brown wire) or a faulty connection possibly in the ignition switch. I guess the only thing i can think of for now, is to get the rest of the ignition switch, so that if i have this problem again, i can put new switch and key cylinder i have together, plug them into the connector at the bottom of the steering column and try it, and hope that it is the problem if i am away from home. then if that works, i guess i would go ahead and change the igntion switch in the column. does that sound like the thing to do?

thanks,
STeve
 
Hope your feeling better Steve. I haven't had any appendix problems and from what I've heard it's not fun.

That sounds like a good plan Steve. If it don't start by doing that try wiggling wires around here and there, especially the ones that pass through the firewall bulkhead connector because the bulkhead was notorious for bad connections. If it then starts you have a bad connection somewhere but by your original description it sure sounds like just a bad key switch. Sorry I told you it was a breeze to change the key switch. I thought yours had the key in the dash like my 68 Cuda so that's why I said changing it was a breeze.
 
yea, i'm feeling alot better, thanks


i'll try the bulk head connector. maybe pull it off and see if there is corrorsion in there or if something appears to be loose. And get another ignition switch for backup.

now to find the ignition switch, i'll try yearone, paddock, etc.

Thanks again

Steve
 
glad your good enough to give the ol' car some well needed attention. welcome back. definitely check all connections. was the coil ever out? there is a ground strap under the cap that uses 1 of the coil cap screws to mount it. check if that is there. also check rotor. i just changed my msd cap/rotor and couldn't believe how corroded it was after 1 year.
 
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