Ignition Switch Problem / MSD Ign.

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Brad426

Brad426

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I need suggestions. 1969 Valiant. I removed all the stock ignition wires and equipment and installed MSD, everything. The FORD/GM side of my brain was thinking to tap into the blue/white ("on" position) wire out of the ingintion switch to power the MSD. What I discovered after 2 hours of scratching my head is this. If the key is in the on (not acc.) position the blue/white wire is hot. As you turm the key to the start position the yellow becomes hot feeded the starter safety relay and at the same time the blue/white wire has no power while cranking. Thus I had power the the MSD in the "on" position but, no spark (power to the MSD) in the cranking position :wack:. It was driving me nuts. I looked for a wire that was hot in both the "on" and "start" position. Notta! Here's what I'm thiniking......

Install a relay that is normaly open. The relay is triggered by the yellow "start" wire while in the start position the relay contacts close and provide power the the switched bus bar (MSD brain & accessories) while cranking. When the key is release back to the "on" position. THe relay contacts open and the power is sent to the switch bus bar via the blue/white wire. There will be a very breif moment between the relays but, I don't think it will effect anything. What are your thoughs or any other solutions you might suggest. Thank you in advance.

Brad :prayer:
 
you can splice the two wire together to provide 12v for both start and run for the msd unit.
 
Brad there are THREE wires in the ignition switch system, and you must be careful

1 "Dark Blue", "ignition run" or IGN 1 Hot ONLY in "run"

2 "yellow," "Start" comes from the key to the starter relay, hot ONLY in start. DO NOT tie this to the ignition system, except with a diode, different or second relay, see below

3 "brown" your Mopar "ballast bypass" comes direct from the key, hot ONLY in start, and went to coil+ side of ballast. THIS IS the wire, if you still have a factory switch, that you tie to "ign run" to fix the problem

Now, if you do not have the original ignition switch, you need to do one of several things as below

A You can use the later Jeep starter relay, which has an extra set of contacts:

The two terminals at the far right, G and I, go to the same wires your old one did, the neutral safety switch/ clutch switch, and the yellow start wire. If you have a stick with not clutch switch, ground the other one

The solenoid "square screw" is replaced by the two spade terminals in the middle,

Big threaded stud still goes to battery

Extra terminal on below left (bal) ties into your "ignition run" to provide starting power

B Another way is to ADD a second (Bosch) relay to your start relay. "T" the two coil connections into the original start relay yellow and NSS connections

Hook one contact to the battery stud on the relay

Hook the remaining NO contact to your blue IGN run wire

C The third way is to buy a nice big diode at RadioShack, biggest amperage they stock, and wire from the yellow start wire on the solenoid to the "igntion run" wire. . The diode will either have an arrow (---[<---) or a band (-----[ | ]-----) corresponding to the same layout. Hook the banded end to the "ignition run" wire, and the "unbanded" end to the yellow wire on the start relay. This will prevent "backfeed" into the relay

StarterRelay.jpg
 
Thanks 67DART273, I went the relay route and it works great. Here is my coffee shop napkin drawing....LOL. KISS RIGHT?
:cheers:
 

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YIKES. I have trouble following your diagram, but if you got it workin' that's the main deal.
 
Brad,

I made the same mistake in re-wiring my engine bay. I ASSumed the blue ignition wire got power during cranking and the brown wire was just to bypass the ballast, so I didn't need the brown wire. I found the engine would fire only as I let off the starter. Took me a while to figure that out since playing with new carb problems, etc. I added a jumper wire at the starter switch so the brown terminal connects to the blue wire. I don't need to bypass the ballast since I have electronic ignition (Crane XR700), and will eliminate the ballast anyway when I upgrade to HEI.
 
Thanks Bill. I did sort of the same thing with a relay. I've started the engine 5 times since the "discovery" and all seems good so far. I completely removed all ofthe ballast system in my car to install all MSD. I hear tha CRANe is a good system. How do you like it?
Brad
 
The Crane XR700 (and XR3000) is an older design. I put one on my 69 Dart ~1990 (from J.C. Whitney) and my Newport ~1994. The main drawback is you must keep the ballast resistor even if you upgrade your coil (to protect their box I assume), same restriction as the Mopar box. The XR700 main advantage is the optical pickup should be very precise, though you must insure no phasing problem. However, one pickup failed on me and replacements are ~$50 (fixed mine by changing the IR emitter component). The original Pertronix Ignitor has similar coil switching, but their later Ignitor II or III eliminates the ballast requirement. For a good, low-cost ignition today, I suggest a GM HEI based system (many FABO posts). For SB or RB, the $45 "ready to run" distributor is a great deal. Wait a bit and they may have BB and slant versions.
 
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