Back in the good old days. The after market high performance ignition system kits always came with a separate isolation diode. Most people would not read instruction about installing the diode. Consequently the engine would not shutoff. There is enough residual voltage created by the alternator to power the coil and create a spark at the plugs. Yes, the diode not being installed is the problem.

A really nice EFI conversion kit with a 15 cent installation. The horror, the horror.

The brown wire is for the gen light. When charging the bulb has + voltage on both leads, and light goes off. When alt is not charging the alt supply's a ground and light turns on. Should have found another switched 12volt circuit to power the FI.

As someone already said, that is a GM alternator and were known to back feed. MSD used to supply a diode in the kit to be installed if the engine continued to run after key was shut off. It sounds like it has a dead hole when it's running.

The brown wire connects downstream the alt/gen light and a half wave rectifier inside the alt. If you looked on a scope you would see the 6v is pretty ugly. The purpose is to self power the field in the rotor of the alternator and place opposing voltage to the dash light to extinguish it. Your diode fix is reasonable. Isolating the FI system completely from that portion of the ignition circuit would be better. Converting a points GM to hei in the early 70s would yeild the same result. Depends on the car whether you can find a swit h ignition source that is not connected to that feedback circuit or whether you must use a diode or relays to isolate.

Great video Ivan. Does that jeep have a rod knock? Wow it sounds terrible.

Love the fix. Another brilliant diagnostic.

I remember back in the day my dad having old junkers that would stay running after you shut it off. The whole car would shake until it finally died. Sometimes, if it was really stubborn, you'd have to go out back and cover the exhaust with your shoe. Good times.

As others have said that brown wire was to turn off the charging light on the dash. When you have battery power on both sides of the light, the bulb turns off. The diode will fix the problem. Next question is, does this vehicle have a charge light or possibly a volt meter? It may have an ammeter, but that is probably a shunt under the hood with two small wires from the shunt to the meter in the dash to read charge. That's why voltmeters were used instead of the shunted ammeter. Good one Ivan.

appreciate your methodical approach to finding the issues at hand.nice work ivan.its why we keep watching bud.

I think the Altanator field wire goes to the dash light that has ignition power to one side and the other side goes to the field wire on the alternator. That’s why there was 5 volts when key was off because the lamp was acting like a resistor. I think the diode probably should go before the dash light so the light will illuminate when alternator is not charging.

I love these interesting cases!! Great job Ivan!

So fascinating, again. Great video.

U r the MASTER of the one dollar super fix! Great video.....

Another great video Ivan! Bought a TS101 per you link and super impressed. Thank you!

I really love your site. Among the sites I watch every time they come out are yours, Eric's and Wes. It looks like that Jeep has no clutch starter lockout, bypassed, or didn't come from the factory. Keep the great, informative videos.

Classic. The old school charge lamp feedback keeping it running. The engineers back then expect the coil to draw enough to pull it down.

Good diagnosed man! Well done!

IVAN, Your diagnostic skill is top shelf for most any vehicle out there. Fixing this jeep is almost childs play for you. Nicely done Ivan.

Hi Ivan, great video as always. Remember that when installing a diode in series (for any application) there will always be a voltage drop (+/-1.5v)

This reminds me of my 86' Dodge Lancer. The battery stopped charging and I changed the alternator. However the problem was the voltage regulator which was in the PCM because why not. Great video Ivan.

We converted early 1960s model forklifts from generator or externally regulated alternators to Delco SI 3 wire internally regulated alternators. We would encounter the same problem when connecting the control wire with the ignition switch if a resistance wire wasn't used. It could also be solved by replacing the ignition switch with one that had an accessory terminal that wasn't connected to the ignition in the off position and connecting the control from the alternator to acc.

Pre-Chrysler. Notice the square ignition key. Fun to see the old AMC 6cyl ..... so much of that is still evident on my XJ even after Chrysler and Daimler got into things.

Great video as always. I’ve learned a lot from this channel and it’s intelligent viewers 👊🏻👍🏻

Thanks Ivan!

IVAN, YOUR SCIENTIFIC APPROACH IS SUPREME AND SO ADVACED BASED ON SCIENCE. POWER TO YOU. YOUR SOLUTION TOOK CARE OF THE ISSUE GOT THE OWNER AND THE SHOP TOTALLY OUT OF TROUBLE. IT MUST BE YOUR ENGINEERING BACKGROUND AND TRAINING. YOUR INTIAL JOB YOU LEFT IS THE BEST DECISION YOU EVER MADE TO YOURSELF.

👍👍 very good work ivan

Steering all over the road... My 1993 Chevy C1500 had a seriously sloppy steering feel. I pulled out the rag joint and replaced it with a Jeep U-joint sub-shaft (a common modification). It was a very worthwhile improvement! A couple of years prior, I had done a complete frame-out front end refresh so there was no question the rag joint was now the big culprit to the steering slop feel.

Nice to see you help the (aftermarket) guy ! For a change 👍 Alternator is on its way out, should charge without that wire (possibly the 2 alternator wires are swapped)

I installed brand new wiring all around in a Vickies. In the situation where the vehicle wouldn't shut off was fixed by the supplied diode that goes into alternator wire that has to be installed. That prevents backfeeding voltage to ignition switch.

Ivan: My experience comes from the vintage late 1960's Ford world and the back feed issue with this Jeep also afflicts some aftermarket ignition systems there as well. The factory points/condensor ignition system on the older Fords includes an inline resister wire (pink) in the underdash wiring harness that effectiely steps down the voltage to the coil to keep the coil from getting too hot and the ignition points from burning up prematurely. The "I" terminal on the starter solenoid momentarily sends full battery voltage (12V+) to the coil only when the starter is engaged to assist in starting. Once the engine starts and the key returns to the "run" posistion, the 12V+ feed at the "I" terminal is interrutpted and the "regular" coil voltage ( often sometimes less than 8V+ If I recall correctly) back feeds to the "I" terminal on the starter solenoid. Aftermarket ignition modules such as the Pertronix Ignitor I need something on the order of a minimum of 8 volts to trigger the ignitor module. Some older stock harnesses develop higher resistance over time and drop below that threshold, requiring a resistor wire bypass to work reliably. Occasionally a DIY owner will cobble together something that may result in a similar back feed issue you saw with the Jeep leading to ignition miss and stalling as the ignition circuit builds additional resistance as the heat under the hood rises. Regards, Jeff

The answer was posted early on. But you will get that backfeed with any conventional alternator, because thats how they cause the charge warning lamp to extinguish - battery voltage both sides of it. The change here is that with the aftermarket kit, the only load on the ignition supply is the relay coil. However with a conventional setup it tries to feed the coil primary but there's too much voltage drop across the lamp, it limits the coil primary current to maybe 100-200mA and theres going to be no spark, the engine will stop.

Nice, easy, and cheap. A customers dream

Why would you spend all that cash on ignition and fuel system when the thing is a wreck. Think I would have spent my money on getting it to drive in a straight line.

Who am I to say but, when you used the butt connector on the diode, I thought it best to fold over the diode wire so there would be 2 strands inside each end of the but connector making a better connection & double the chance to hold its grip. Just a idea. I realize that I am speaking to the diagnosis guru! The unrenounced master of diag! You always nail it & that is why I always follow your work! Keep up the awesome diagnosis Ivan!!!

Great work. Nice to see your subs are increasing. Deservedly so. Hopefully, you hit 200k by year end👍

Reminds me of my old CJ’s although no aftermarket electronics!!!👍

Nice fix for a Bad or no diode in alternator or the original ignition module had one! The Sniper was in my crosshairs until you said you already found an alternator issue.

I had a '54 Ford pick up that I upgraded to 12v alternator. I was a novice at that time. I experienced similar problems working with the correct connection for the exciter wire for the alternator.

good work, the brown wire is for charging light or resistor, that what make the alternator start charging, the i terminal on the solenoid is to bypass the resistor for the coil when cranking the engine, on older system with point

Nice job.

Nice repair, good t-shooting. I think you should have folded the diode leads onto them selves, same for the wires. Being thin, they would crimp better with double wires. That's been my experience. Thanks for the video.

I remember my '81 Olds Cutlass had a removable diode (and possibly voltage regulator) mounted on the side of the alternator. I think my '77 Pacer (American Motors and related to the Jeep) had something similar. They were easy to replace. I did mine as standard maintenance. You could also replace the bearing set on the alternator. With proper maintenance they could run a long time. Later cars didn't have that option anymore.

The primary issue is that the I terminal on the coil should only have voltage during cranking. It should not have voltage before or after cranking. It is commonly used to provide full voltage to the ignition system for easier starting. Resolve that, and you resolve the issue. The voltage you found at the alternator wasn't direct ignition voltage. The brown wire connects to the indicator bulb in the cluster through a resistor. The other side of the bulb is connected to ignition voltage. That is why the voltage drops significantly when you touch a simple test light to the brown wire. There isn't enough current available from the alternator, through the resistor/bulb, to keep the engine running. The problem was, and still is, a hacked wiring job. There was an additional back-feed because of this, which also wasn't enough to keep the engine running at key off. That was evident by the voltage on the solenoid's I terminal at key on. That low-current back-feed, in combination with the normal alternator back-feed, was enough to keep the engine running. Cut either, and it shuts off normally. You unintentionally added a new hack to the mix, instead of fixing the original problem. The charge warning lamp cannot indicate an over-charge condition now because of it. Thankfully, that is rare.

Can’t solder to it, maybe fusable link. Metal type, ??? Nice fix. Gotta love a project car!

Hi Ivan GM had that problem back in the 70's, the back feed I believe fed though the alternator light on the dash. I think the fix was the same as you add a diode to block the power path. I think that the internal regulator now has a back feed diode in it. possible that the regulator has a problem. Rich

Ivan it looks like an explosion in a pasta factory under the hood....LOL....sounds like a thrash machine running....good ole straight 6

That'a good one ! It's knoking bad !!

I have seen similar problems like that. I had to put a diode on an older Chevy feed wire back to the dash. The generator light would stay on, had a back flow to the dash, diode stopped the problem.

Thanks for the videos. I invented /patented the screw in piercing probe years ago. Remember to liquid tape the hole in the wiring jacket after piercing a hole to reduce water induced wire corrosion. I’ve seen on an mis-wired vehicle a spinning radiator fan generate electricity (after a key off) and keep the ignition circuit powered and the engine running until the fan slowed down (almost quit spinning).

Nice old Jeep.

That jeep would make a good boat Anker!

All AMC vehicles with electronic ignition had a dedicated ignition feed for this exact reason. Use the right wire and you don’t need a diode.

The alternator idiot light feed and the ignition feed need to be switched separately at the ignition switch. Old school stuff. The idiot light is fed 12v from the ignition sw and grounded through the alternator VR when not operating. The alternator VR outputs + voltage on this circuit. + on + to the idiot light and it does not illuminate. The diode repair does not address the improperly wired ignition source.

I know that looks like my work, but I promise I've been nowhere near PA. Thanks Ivan!

18:45 - no wonder crimping has a bad reputation with a crimp tool like that.

The single strand wire may be a resistor wire. Old school. The alternator trigger wire was fed through the idiot light from the ignition accessory terminal through a resistor wire. The wire was usually looped up and taped in the wire bundle behind the dash to meet the required value. Look up a 1973 c10 pick up alternator wiring diagram.

There used to be a fix for this issue by just wiring in a resistor to the brown wire. The original charge bulb or gauge was enough resistance to prevent the back feed problem

I ran across this. The alternator was bad. Replaced it and it was a fix .

I had the same thing happen when I put a 60 amp Delcotron alternator on a Farmall M. A diode fixed the problem. A small light bulb will also work.

Ahh the magic diode. I had this same issue on a luttron lighting system, damn Occ sensor would feed back through each other, Also keep in mind folks these diodes also have a PRV voltage and bias voltages. Great vid and jeep my buddy had one back in 86. Should just leave it 85.

I remember having to do the diode trick on my old 64 Chevy when I went from an external regulated alternator to an internal

Back in the early '80's I had a customer bring in a late '70's Ford, station wagon I think, that ran fine but wouldn't shut off when the key was turned off. If you opened the throttle a bit it would die but otherwise would idle forever with no problem. Ask the customer what had happened prior and found out the old battery died and all they had was a Chevy battery. The pos and neg are backwards from the Ford and the ground cable was too short so they moved it from the engine block to the frame. Installed new Ford battery and put neg cable back on engine block, fixed. Never did understand that one.

Hopefully I can shed a little light on this type of starter setup.... I haven't really worked on jeeps much but that setup is basically the same as Ford used for decades.... the "S" terminal is the one supplied power to close the solenoid the "I" terminal should be factory wired in to the ignition coil circuit after any ballast resistors, to supply full battery voltage during starting, because the coil normally would receive roughly 6 volts running. The thought was power draw of the starter could drop the power low enough to be hard too start or not start at all. Your solution is not a bad one by any means and I have no idea what else Chrysler Corp. may have used that terminal for from the wiring they may have used it to also 'wake-up' the voltage regulator. I suspect who ever set up the wiring instructions wasn't aware of that use because many vehicles never used it but since jeep was frequently using Ford ignition systems and carburetors at that time it is likely that's why they did it.... Side note back in the days of electric chokes on carburetors most Ford's used a choke that operated on roughly 7½volts *A/C* they used the stator circuit on the alternator and no other wiring or switches.... because they were only powered when the engine was running and the power supplied was changed by engine speed meaning the faster the engine ran the quicker the choke opened....

Brown wire goes in series with the lamp for the alternator on the dash.

That's some old Texas inspection and registration stickers on the windshield.

Ivan that wire that would not tin maybe a resistance wire .Nicrome cannot be soldered

Stay-Brite silver solder kit, with its special flux may work on that wire.

Those were not Jeep's best days. If I remember correctly, that was about the time AMC was going belly up and the future of Jeep was very much in doubt. It was also when the military was opening up development of a new troop carrier, which GMC won and took away most of the market for Jeep. It was a very dark time for the brand.

O2 sensor wire also does not solder well unless you scrape off the nickel plating or use an aggressive acid flux

Back when I was a wipper snapper that play in the steering was normal🤣Also I would have put another piece of heatshrink over the diaode & the wiring just because it is bound to go through water/mud & that then becomes a potential failure point in the middle of nowhere & customer may not know how to fix it.Cheers Ivan.

That thing sounds like raggedy school bus.

I would cover the diode with heatshrink tubing because electrical tape has a habit of unwrapping itself unless you fit a cable tie to the finishing end if the electrical tape !

Been there, done that many long years ago doing an engine conversion swap on a old Ford truck. Put in a newer 351M engine, and in the process the diode came off the wiring harness. Started up just fine, just couldn't shut it off! We ended up using old fashioned nylon spark plug wire pliers to pull the coil wire off the ignition to shut it off (and got zapped for our efforts). Once we got it shut off, my dad commented that he'd seen the diode and picked it up - did I suppose it was the culprit? Duh!

These older alternators send power back out through the charge light in the dash as the resistor in order to determine how much power is needed to charge the battery. When the ignition switch is keyed on, it lights the charge light also telling you the battery is draining. When the alternator starts charging, it equals out the current flow through the charge light and makes it go out. This could cause issues back feeding power back into the ignition system when the key is switched off is the reason why they install a diode. Many people used to just tie the two sense wires together and the alternator would charge at full capacity until it boils out the battery and burns the unit up. Had a similar issue when a buddy bought a converted 12v old ford tractor that used a GM alternator. I had to wire in a light bulb into the circuit and he told me that lamp stays lit and it drains the battery down. You have to rev the snot out of the engine in order for it to spin fast enough to engage the alternator but he didn't understand. The purpose of the lamp was telling him the current is flowing away from the battery and not into it causing the battery to run down. Hard to explain to some that dont understand how electronics works.

I was totally off on my first guess - I thought the ballast resistor and its bypass on the starter solenoid had been miswired and used for the aftermarket ignition source. That solid wire that won't solder is likely Nichrome. It was used on vehicles with ammeters instead of an idiot light for the alternator. Normally, the power would go thru the idiot light to provide current to get the alternator field going, but with no idiot light, some resistance was needed - Nichrome has some resistance.

Nice fix the wire was obviously the feed to energies the alternator and once it’s turning produce voltage so was back feeding, I’m pleased the wire wouldn’t take solder as just a soldier joint is no good on its own has to be mechanical as well as solder otherwise could break free with vibrations

Great channel thanks

I had a similar issue when I installed an alarm with remote start on a motorcycle. The engine wouldn't shut off with the key. So installed some diodes on the coil packs and that did the trick.

Danger will Robinson Danger ! Scary riden

you better park that thing before you end up walking

The positive battery terminal looks like Medusa's hair!!

Back to the drawing board. I'd slowly go through all the instructions again and even seek out professional videos on YT for the Holley Sniper EFI install on that generation of Jeep. Something wasn't done right with the initial install. Cool CJ-7 tho.

@19:05 (Crimping that fine wire) fold the wire back about 1/2in onto it's outer sleeve then crimp. It will be a lot more secure. ↪

The other side of the lamp goes to a positive (15) ignition switched. So when the engine is running the lamp receives 12 volts on both terminals and suhts off. That's the work of the lamp on the dash with the battery symbol and that's how old cars work.

Way back I got the urge for a Jeep. I test drove a one year old beautiful white CJ7. The canvas top made lots of wind noise and it took both hands to keep it in the middle of the lane. That killed my interest in Jeeps forever.

Reminds me of a hack job on a flight test. Something was staying on after they tried turning it off. I asked them to draw a circuit schematic of their hack. Looked at it for a minute and said put a diode in a certain spot. Problem solved. A backup battery was backfeeding the gate on a mosfet. Like I said, a hack.

Thank goodness the owner "made it better" by ruining it.

That Jeep was molested by removing the Carburetor. People never satisfied.

This is a 1985 jeep. Chrysler didn't buy AMC /jeep until 1987. That wiring diagram was all AMC / jeep.

That was nice. Cool old Jeep - There's something about "primitive" some of us like. I suspected that was getting a diode just from the title of the video, wasn't sure where before watching it.

install a rectifier for prevent back feeding....

Almost no parts required, very nice.

I've seen plenty of old wires that dont like solder, my solution would be to have a longer exposed part, scrape it with a sharp knife and then twist with the part you want to solder, also use a slightly higher temperature and make sure you use leaded solder (I don't know about the US but in the EU they will only sell unleaded solder so I import mine from china).

It would be interesting to know if that has a charging light and volt gauge from the factory. Those old Delcotron alts are known for leaking diodes triodes. So though it will charge ( may not put out rated amps but still should produce good system voltage) the light will be on dimly. Depending on which diode leaks, it can cause a backfeed through the ignition system. I 1st saw that on my grandfather's 75 Olds. The light would come on dimly and the car wouldn't shut off via key unless the connector for the alt was unplugged. A new alt fixed it.

I also thought Diode, a few seconds before you said it, but the word Relay also appeared out of the grey matter lol. Is the alternator wire a warning light wire but the bulb is way too high a wattage so a bit extra current is going to the altenator WL terminal. I could be talking crap, and my logic is for old lucas alternators with leaking diodes.

“It’s hard to keep it on the road”. That’s a typical CJ thing. Even worse if you are running H78-15 bias ply tires.

Appears the alternator's built in diode pack has gone wrong

Between 1970 and 1986 Jeep was manufactured by American Motors before they went out of business. This CJ is pre-Chrysler motors.

Most likely that single strand wire was the resistor (resistance wire) that showed in your schematic. Usually that kind of wire is made out of iron and not copper at all so your solder will not tin to it.