Ignition system / electrical issue

[jeepboy45]

Hey everyone....I've got a good one for you this time...

I decided to go with the MSD ignition upgrade a lot of you guys are talking about.

I currently have a 10 year old Centech wiring harness in my CJ7 V8. I stripped out every old wire when I did my resto approx 10 yrs ago, and went with the Centech harness. Great harness, and every wire is labeled....

My Jeep has sat for 1 year with a bad Transmission , not started at all. A few months ago, I dealt with it, and some other suspension related mods.
Got the Jeep running about a month ago. One issue I noticed is when I go to start it, sometimes the starter kicks "out", like a solenoid is going bad. But nothing serious. I mention this to cover all bases...(maybe leading me to a bad ignition switch)

But please read on. I tried to cover the whole issue from beginning to my current state.

Here is the problem at hand:

I considered going with the TeamRush MSD igniton upgrade, but fully decided to do it after reading BusaDave9 's writeup a couple months ago.

Now I have an issue. I cant shut off the jeep engine. I had this problem with another vehicle years ago, and it was the starter solenoid somehow keeping the engine running.

So I replaced it yesterday, no change.

The first diagram shows my existing wiring with the stock brain before I changed anything. It is a crude diagram but easier to follow than a schematic.

The second one shows how it is wired now.

I used my key "on" 12 volts wire that formerly went to my ballast resistor to power the MSD and go to the solenoid. I just spliced the MSD into that wire. See second diagram for how it is currently wired.

The jeep starts fine... 12 volts at the "I" terminal on the solenoid when key is "on"... I get 12 volts to the "S" terminal on the solenoid when the key is turned to the "start" position. I have power at the coil (obviously)

However when the key is turned to the off position to shut it down, the engine continues to run.....not just diesel or run-on

At that point, I have nearly 14 volts at the "I" terminal on the solenoid (this must be alternator power, not just battery power)

I have to smother the engine to kill it (or pull the coil wire which from experience can be quite painful) When the engine is smothered, the voltage drops from nearly 14 at the solenoid "I" terminal to the battery power of 12 volts.

Last night I discovered that when the engine is still running with the key "off", pulling the alternator wire plug from the alternator kills it.

Personally I believe it must be a wiring issue, but since I have an extra alternator sitting on the shelf I decided to change it. No difference.

It could be the ignition switch, but I doubt that it decided to out on me the exact time I did the ignition upgrade.

I feel there has to be a wiring issue that I am overlooking. Not necessarily a bad wire, but something in the system that must be changed to allow for the MSD conversion.

BusaDave9 has been a world of help to me, but it is difficult to diagnose over the phone or the internet.

Any suggestions or help would be appreciated.

 

[jeepboy45]

Not even 5 minutes after posting this, I got a PM from someone in the "know"... identity to be revealed later after I try his solution.

It is a diode missing from the "excite" wire off the back of the alternator. He asked me if by pulling the alternator wires if it kills the engine.
(he never saw my post above describing this)

I told him I would try this, and let him know.

When/If this works, I will update here and let you know the details.

If anyone has any imput or thoughts on this, please feel free to throw them up here!!

Stay tuned for more to follow...

This could be need-to-know information for anyone with similar issues..

brian

 

[rlitavecz]

I had the same issue with a VW years ago. I used the same wire from the ignition switch to feed the alternator field and the ignition coil. Once the engine was running, I could not shut it off. I solved this problem by moving the alternator feed wire to the accesory terminal on the ignition switch. I did not have any "accesories", so this worked out great!

 

[IOPort51]

there is something about the wire to the exciter from ignition switch is a resistance wire or is attached to an idiot light that functions as a resistor.

 

[JR74CJ5]

This was happening with me, but very briefly.

I installed the DUI distributor, MSD "streetfire" ign box at the same time, and a new alternator after those...

My charging system quit on me. So new battery, alt etc all purchased.

then i bought new solenoid and regulator (voltage).

Had all wired up and was charging, but still off the "back-up" charging circuit.

Brief history: in my year model, there is a ALT / AMP light built into the gauge cluster for speedo, fuel, and temp. This light is part of the main charging circuit. The alt requires a small amount of voltage to "start" its output. I mention this because one day as I am sitting in my jeep getting ready to shut it off, it kept running... Like you are talking about not dieseling or run on, it literally could still be driven with key out.

I had just done some re-wiring, so i wiggled a wire and it died. couldn't get it to do it again.

Can you take a picture of the back of your alternator (just the spare one will do fine for me) and post it? Also if you can get a semi close pic of the wires attached to the back too...

I'll try to tell you what i just did this weekend to find my final fix thus far, though I admit it hasn't been road tested yet, it seems to be the fix of all my woes.


~ JR

 

[jeepboy45]

I have it on authority that all I need is a diode spliced in the "excite" wire off the back of the alternator. That will keep current from traveling "backwards" toward the harness and therefore the ignition switch circuit.

This is from a very reputable source. I am actually trying to solder it in right now, but for some reason the wire is solid---possibly steel--- and doesnt want to accept solder, and I am trying not to just wire connect/crimp it in position.


I am assuming that the brain must have acted as the diode is going to do for me now, and by eliminating the brain, I caused the issue.
I will detail its success as soon as I test it....
over and out for about an hour....

brian

This was happening with me, but very briefly.

I installed the DUI distributor, MSD "streetfire" ign box at the same time, and a new alternator after those...

My charging system quit on me. So new battery, alt etc all purchased.

then i bought new solenoid and regulator (voltage).

Had all wired up and was charging, but still off the "back-up" charging circuit.

Brief history: in my year model, there is a ALT / AMP light built into the gauge cluster for speedo, fuel, and temp. This light is part of the main charging circuit. The alt requires a small amount of voltage to "start" its output. I mention this because one day as I am sitting in my jeep getting ready to shut it off, it kept running... Like you are talking about not dieseling or run on, it literally could still be driven with key out.

I had just done some re-wiring, so i wiggled a wire and it died. couldn't get it to do it again.

Can you take a picture of the back of your alternator (just the spare one will do fine for me) and post it? Also if you can get a semi close pic of the wires attached to the back too...

I'll try to tell you what i just did this weekend to find my final fix thus far, though I admit it hasn't been road tested yet, it seems to be the fix of all my woes.


~ JR

 

[jeepboy45]

The verdict is in:
The diode is necessary in this case.
I wish I could put the full size pics in here and not just thumbnail attachments, but I dont know how...

Either way, these are the diodes that were recommended to me by .................JEEPHAMMER... Yes, if he suggests it, I listen to his recommendations as gold.

I mentioned to him my problem, but that was before I noticed I could kill the engine by removing the alternator wires.

He responded by telling me that he thought I could kill it that way, and if I could, this is what I needed to do.

The band on the diode must be installed towards the alternator, keeping alternator current from "backflowing" through that wire.

THANK YOU JEEPHAMMER!!
For those who do not know of him, he IS TeamRush, and the man who suggests----RECOMMENDS----upgrading the factory Ford/Jeep ignition instead of replacing it with HEI...

I owe him a beer, and a thankyou...

Check out the writeup by BusaDave9 about this ignition upgrade... He did a very nice pic spread of the whole process. Thanks to you too Dave. He helped me along with the diagnosis of my issue written above, as well as guiding me when I had questions...

I will be posting this "need to know" information about the diode in his thread...

Thanks to all who responded. I appreciate the useful information, and hope this information provided here can help those in the future with similar issues.

Brian

 

[jeepboy45]

See BusaDave9 's writeup on the "Team Rush Ignition Upgrade" by going here:

http://www.jeep-cj.com/forums/f2/teamrush-ignition-upgrade-11416/

thanks to people like Dave who share their knowledge, the JEEP world is a better place!!!

 

[BusaDave9]

Excellent information about the diode.
Good to hear you got it going.