Electric choke issue

[Nick I]

Good evening gurus,

Sorry in advance for the long post, but I'm working on an issue that's almost a year in the making.

I've ran into a bit of an electrical issue and I believe it's narrowed down but could use some input. First off, lots of electrical changes. 1967 Barracuda 383 4speed. Now has the American Autowire classic update from back to front and the Mancini orange box electronic ignition. I also added an in dash tach and converted the ammeter to voltmeter. All bench tested fine. After installing everything but the engine bay harness, I hooked up a battery and all was well. Fast forward several long months, and I finished the engine bay. When I went to hook up the new battery, sparks flew.

So I started disconnecting things, starting with the ballast resistor and ignition box harness, and doing continuity tests between the positive and negative cables. I got to the point of disconnecting the electric choke positive cable, at which point there was no more continuity between the battery cables. During my searching, I had found I had continuity between the block and the coil, until after I disconnected the choke positive, now no more coil continuity.

I'm not sure if my electric choke is bad, or if I've wired up the ignition and coil incorrectly. I followed and have triple check all the diagrams and am leaning toward a bad electric choke. When it's disconnected, everything seems to be fine. I can't run the motor yet because the radiator is still out but the starter engages.

Let me know what other info I can provide.

 

[Oldmanmopar]

Electric choke is connected to a 12v ignition on wire. Always use the correct amp fuse or fusible link for anything wired that is aftermarket.

 

[67Dart273]

I think you made a mistake in your troubleshooting, or the harness is somehow wrong beyond the choke. There is no way "with the key off" to get choke power continuity in that part of the circuit

On a side note, there is "really" too much load on the key switch for the "run" circuit, and this is part of the reason that many Mopars overcharge, HOW THIS works

You have (originally) "the path" from the battery, through the key, to the ignition system and VR. This "run" IGN1 line provides ALL key switched power in the "run" position, under the hood---ignition system, VR, alternator field on 70/ later cars, choke if used, and on newer cars, sometimes 'smog doo dads.'

VOLTAGE drop through that path--through the connectors and the key switch itself cause LOW voltage to the VR "sense/ power" (IGN) terminal, which them ramps up to cover the drop. What this means is, the battery then runs "too high."

I always recommend you break the IGN1 "run" coming from the key, use the key end to trigger a relay, and use the relay contacts to feed the engine bay side of that circuit. And as OldManMopar says, "properly fused"

So far as your choke, that can be ???

 

[67Dart273]

WHAT YOU CAN DO in these types of cases Get yourself a BIG wattage 12V lamp, like an old headlamp or an 1157 or even a dome light. "Rig" it with a socket and pigtails. Disconnect battery ground and wire the lamp in series. Now you can "short anything" and all that will happen is that the lamp will light. You can then troubleshoot without burning it down

Suspect the alternator connection, any stereo, and obviously ANY other load that is not key switched. Headlights, brake lights, the 4x hazards circuit, anything that is "hot" at all times.

Also take a look at the battery cable/ starter connections, any possibility they are "turned" on the studs and jumpered across?

 

[Woodys_Cuda]

You can easily test your electric choke for a short with an ohmmeter. Like was said earlier the choke should be connected to the ignition run wire.

 

[Nick I]

Ok so I'll try and respond to all, apologies if I miss anyone.

The choke is wired up to a 10 amp keyed circuit that American specifically lists for this purpose. When the key is off, 0 Volts, when key is in run position, 12.25 volts.

I believe the choke cap is fried internally. It only has 5 ohms resistance. From what I've found, it should be between 12 and 20 ohms. If I disconnect the hot lead, I can connect the battery and the engine will crank and all electrical works. If it's not this, then potentially, the America Autowire fuse block could have a problem. But the fact that the choke wire is dead when the key is off tells me that's not the case. It also has no continuity to ground unless it's plugged into the choke.

The alternator is single wire now with no field connection per the AW diagram and the Mancini ignition instructions. Headlights brake lights signals all function as expected, hazard switch functions but not well, not shorting out though as far as I can tell with the meter. Radio isn't in the car but as with all other open connections, they are terminated and insulate (accessory plug, heater, windshield wiper).

I have a other carb with electric choke that I'm going to pull out and test. If I have the same issue then I'll be reaching out to American for help as there are no fuse block diagrams available.

Let me know if I've missed anything, please!

Another question, should the negative post on the could have continuity to the positive post and should it have continuity to ground/negative battery post?

67dart273, you helped me find my first electrical issue with this car 2 years ago. Forever grateful!

 

[67Dart273]

The neg/ pos post MAY show continuity in at least one direction (reverse your meter leads) for a number of reasons

Loads permanently connected such as stereo or alternator WHICH HAVE solid state devices
AND something along the line of a radio supression cap the charging current of which will temporarily show continuity, and depending on the sensitivity of the ohmeter, may be hard to resolve

For example, if you reverse battery connections on an alternator (output stud to case) it will be a direct short because of the rectifiers. Likewise, a stereo/ radio or remote amplifier

I almost NEVER use continuity, except down to the "last switch and wire" of a problem. I almost always use "hot" which is why I suggested the series bulb. This allows you to "see" what is going on, as well as measuring current through a fault

Ohmeters are way too sensitive, can be damaged if any voltage present, and can lead you down a rose path "generally."

 

[Nick I]

The neg/ pos post MAY show continuity in at least one direction (reverse your meter leads) for a number of reasons

Loads permanently connected such as stereo or alternator WHICH HAVE solid state devices
AND something along the line of a radio supression cap the charging current of which will temporarily show continuity, and depending on the sensitivity of the ohmeter, may be hard to resolve

For example, if you reverse battery connections on an alternator (output stud to case) it will be a direct short because of the rectifiers. Likewise, a stereo/ radio or remote amplifier

I almost NEVER use continuity, except down to the "last switch and wire" of a problem. I almost always use "hot" which is why I suggested the series bulb. This allows you to "see" what is going on, as well as measuring current through a fault

Ohmeters are way too sensitive, can be damaged if any voltage present, and can lead you down a rose path "generally."

Understood. I have some extra light bulbs a socket and wires ready to go for this weekends testing.

Just to clarify, should I be checking keyed or unkeyed circuits since the problem "goes away" when I disconnect the keyed choke hot wire? Also, any reason that the choke issue would cause the coil to ground? My guess is because they're both on the RUN circuit?

 

[67Dart273]

Yes, choke is tapped offf 'run.'. There are only so many outputs from the key switch
1...ACCESSORY, hot both in "run" and "accessory"
2....RUN or IGN1....hot ONLY in run, goes dead in "crank."
3....Start...hot only in "start" feeds and triggers the start relay, nothing else
4....Bypass or IGN2....Also hot "in start" but a separate contact and goes to coil + side of coil. This is the ignition power source for "start"

If disconnecting the choke "fixes" it I'd say you are there. Frankly I'm not intimately familiar with "what all" is a choke. I know there is a heater, there may be a radio cap (which can short) and the OEM setup has that odd thermal timing device, and surely it can develop problems.

 

[Nick I]

Yes, choke is tapped offf 'run.'. There are only so many outputs from the key switch
1...ACCESSORY, hot both in "run" and "accessory"
2....RUN or IGN1....hot ONLY in run, goes dead in "crank."
3....Start...hot only in "start" feeds and triggers the start relay, nothing else
4....Bypass or IGN2....Also hot "in start" but a separate contact and goes to coil + side of coil. This is the ignition power source for "start"

If disconnecting the choke "fixes" it I'd say you are there. Frankly I'm not intimately familiar with "what all" is a choke. I know there is a heater, there may be a radio cap (which can short) and the OEM setup has that odd thermal timing device, and surely it can develop problems.

Well, turns out the continuity test was a red haring. I had one of the door light switches put which was causing the sparks when trying to connect the battery. Quick call to American Autowire after testing some other leads narrowed it down to the fused circuit for the interior lights. Learning is occurring.

 

[Dave999]

do you have a ground strap that makes good contact with the metal rather than the paint of the engine block and the chassis mount

 

[Nick I]

do you have a ground strap that makes good contact with the metal rather than the paint of the engine block and the chassis mount

Oh definitely! I have ground straps all over the place now with this new wiring kit. Battery to block, block to firewall, core support to harness, you name it.

 

[1969383S]

Not sure this applies with your aftermarket wiring, But if you have a standard 2 speed wiper motor and switch then pull the choke power off the Blue wiper 12V that is protected by the circuit breaker in the wiper switch!

I never suggest pulling loads like this from the ignition system!

 

[Nick I]

Not sure this applies with your aftermarket wiring, But if you have a standard 2 speed wiper motor and switch then pull the choke power off the Blue wiper 12V that is protected by the circuit breaker in the wiper switch!

I never suggest pulling loads like this from the ignition system!

Yeah me either. New harness has dedicated line for the choke.

 

[RustyRatRod]

Not sure this applies with your aftermarket wiring, But if you have a standard 2 speed wiper motor and switch then pull the choke power off the Blue wiper 12V that is protected by the circuit breaker in the wiper switch!

I never suggest pulling loads like this from the ignition system!

I agree. I would not pull from ignition run, either. You don't want anything pulling power from the ignition. It needs to be dedicated.

 

[Nick I]

I agree. I would not pull from ignition run, either. You don't want anything pulling power from the ignition. It needs to be dedicated.

It's not. Dedicated choke is on a 'run' circuit on the new fuse block. I found the issue though. Open door circuit when trying to hook up the battery caused the sparks. Just waiting on a radiator and should be able to finally fire it up.