74 dart can’t get a spark

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Stoney Anderson

Stoney Anderson

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74 dart special edition

Ok so I was driving the other night and the car stopped running. I thought it was gas so I pushed to the side got gas and the engine just cranked. I had it towed home so I can play around with it and I’m about to light it on fire. Hahaha irritated.

Clearly no spark since carb is working properly.

12v from battery traced wire back to the fusible that plugs into the firewall and it keeps its voltage that whole way. I don’t seem to be getting power at the ballast on the blue or green wire.

So I’m assuming that’s why the electric ignition isn’t giving power to the ignition coil which isn’t causing distributor to turn to give spark to plug to get engine to start?

Anyways I’m lost now. It’s the first car I’ve wanted to work on and learn so that’s why I’m here. To ask for help.

Also the aftermarket radio the oil light and e brake light stopped working as well when the car shut off and has not turned on since. Is there somewhere I should check or a master fuse or anything that I should look for? The dome lights still work engine tries to start and does everything it should except get spark. Headlights work. Idk


Thank you and please help
 
See if the engine will start and run holding the key in the START position. If it will, the ballast resistor is probably bad. It won't hurt a thing for a second or two.

Have you actually used a test light to determine your lack of power, or is it just a guess?
 
RustyRatRod said:
See if the engine will start and run holding the key in the START position. If it will, the ballast resistor is probably bad. It won't hurt a thing for a second or two.

Have you actually used a test light to determine your lack of power, or is it just a guess?
Click to expand...
It won’t start at all just cranks and cranks. I pulled the ignition coil plug from distro stuck a screw driver in it put the chord next to it and nothing.
 
Stoney Anderson said:
It won’t start at all just cranks and cranks. I pulled the ignition coil plug from distro stuck a screw driver in it put the chord next to it and nothing.
Click to expand...
So then you have tried it while holding the key ALL THE WAY FORWARD? While the starter is engaged?
 
Go over to mymopar.com and download a copy of the service manual for it. They are free and it will do you a lot of good. You need to familiarize yourself with the circuits for "Ignition 1" and "Ignition 2".
 
If you are not getting any voltage reading, in either crank or run, on either side of the bal res, you have a wiring problem, faulty ign sw, corroded terminals etc.
 
Turn the key to the on position and check the voltage on both sides of the ballast resistor... One side should have 12 volts and the other should have 6 volts...

The coil + wire should have 6 volts also...
 
Clean the bulk head terminals. 74's are noted for corrosion there. The white plugs on a 74 bulk heads have bad corrosion problems. I have had more then one with corroded terminals.
 
Oldmanmopar said:
Clean the bulk head terminals. 74's are noted for corrosion there. The white plugs on a 74 bulk heads have bad corrosion problems. I have had more then one with corroded terminals.
Click to expand...
I was going to come back and post that but I fell asleep. lol
 
Stoney Anderson said:
Also the aftermarket radio the oil light and e brake light stopped working as well when the car shut off and has not turned on since.
Click to expand...
None of us know how the radio was wired in. Factory radio is powered from the switched side of the fuse box.
Oil light power requires key switch in run
Regular brake lights are always hot.

Stoney Anderson said:
Is there somewhere I should check or a master fuse or anything that I should look for?
Click to expand...
The fusible link is the only thing close to a 'master fuse'
Stoney Anderson said:
The dome lights still work engine tries to start and does everything it should except get spark. Headlights work. Idk
Click to expand...
Dome light is always hot.
Headlights are always hot.

As always with testing. Make sure the battery is fully charged.

Basic Standard layout is like this.
(Not shown is the '74 seat belt interlock wiring.)
1664457923899.png

All the wires connected to the battery are always hot.
Q1 feeds the fuses that are always hot.
J1 feeds the key switch.
J2 wires are fed from the key switch run terminal.
J3 is the fed from the start terminal. J3 bypasses the ballast resistor because at start the system votlage is low (10-12 Volts instead of 14is hwhen the alternator is running).

Wires A come and go from the battery.
Wires R relate to AlteRnator
J1 feeds the key switch
J2 is hot key in Run

For the ignition to work.
Key in RUN there should be power throughout the J2 circuit. Measure at the ballast junction and firewall connector
Key in START there should be power at battery voltage in the J3 circuit. Battery voltage will be less than 12 Volts because of the starter's draw. Measure the votlage at th ebattery as well and you'll see this for yourself.

This may be helpful WRT interlock
www.forabodiesonly.com

Ignition Issues on 74 Dart Sport

Hey guys! I’m having a lot of issues with my Dart. I’m like 12 weeks into my weekend project now. I had pulled the engine to do a bearing swap and put it back in. It ran prior to pulling the engine. After I dropped it back in, it would only run while the starter was engaged. After disengaging...
www.forabodiesonly.com www.forabodiesonly.com
 
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Stoney Anderson said:
I will do that now thank you!
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Cool. Also @Oldmanmopar made an excellent point about the firewall connector. Grab it from the outside and gently wiggle it back and forth and then see if it will start. Those connectors are notorious for working loose and getting corrosion buildup and causing resistance or even a complete break in the circuit. Probably not a bad idea to remove it and make sure all the brass terminals are good and clean and no melting has occurred.
 
Oldmanmopar said:
Clean the bulk head terminals. 74's are noted for corrosion there. The white plugs on a 74 bulk heads have bad corrosion problems. I have had more than one with corroded terminals.
Oldmanmopar said:
Clean the bulk head terminals. 74's are noted for corrosion there. The white plugs on a 74 bulk heads have bad corrosion problems. I have had more then one with corroded terminals.
Click to expand...
I’ll try that this morning and get back to you! Very optimistic.
Click to expand...

I also changed ballast resistor yesterday. Cause I’ve heard those go bad quite often
 
Stoney Anderson said:
I also changed ballast resistor yesterday. Cause I’ve heard those go bad quite often
Click to expand...
Check for power with your test light at the steering column connector (key off)
If none take a look at your amp meter connections.
Those sometimes melt and disconnect your main dash and ignition feed.

FYI, with the factory ignition box and coil you can disconnect the plug for the distributor, and on the harness side touch the exposed metal contact to ground and you will get one spark per ground touch.
(That way you don’t have to keep cranking it for testing)
 
RustyRatRod said:
Go over to mymopar.com and download a copy of the service manual for it. They are free and it will do you a lot of good. You need to familiarize yourself with the circuits for "Ignition 1" and "Ignition 2".
Click to expand...
There is no 74 manual over there
 
I would start by finding out if the problem is in the immediate ignition system---that is the box, the distributor pickup and the related local wiring---or in the harness feeding the system

To do this, jumper 12V from battery to coil + See if you have a spark. You can jumper across the exposed terminals of the starter relay to crank, and check of course with the coil wire. BEST is to REMOVE the coil wire and use a SOLID piece of wire rather than resistor/ radio wire. You can even use "low voltage" wire if you "hang" it in the open away from metal.

With key "in run" measure do you have voltage at coil +? Should be NOT full battery, but "down" say 6-10V or so. If it is full battery it means the box and coil are not drawing current

Check box is grounded MUST!!
Wiggle distributor connector in/ out several times, they get corroded.
Connect distributor connector to your multimeter on AC volts and crank. Distributor should generate about 1V AC. Inspect inside of cap and around reluctor/ pickup for rust, debri, damage, and shaft wear/ wobble/ looseness

With key "in run" and coil wire near ground, disconnect distributor pickup connector. Take the harness end of the connector and tap the exposed terminal on ground. Each time you do so, should get one single "snap" spark from coil wire
 
RustyRatRod said:
Well that kinda blows. Is there one that's close?
Click to expand...
The problem is that the 74 has some unique wiring. There's a 73 but it is quite different in some ways. Also, remember, 74 had the "one year" seat belt ignition interlock
 
Ok so just cleaned bulk head terminals and plugs going into it and still just cranking when I turn the ignition. The ignition coil and the ballast resistor jumps from 15 to 12 to 5 volts on my meter for some reason but stays on 12.8 while on battery terminals. Next stop is the steering column connector.

Could the ignition switch be the problem even if when I turn it the engine cranks?

Thank you all for the help. If anyone lives close and wants a beer or a Diet Coke I’m down to hold the flashlight and learn or you can hold the flashlight and mumble under your breath in disappointment like all the car dads hahaha
 
The fact that it is jumping around might be a clue. Have you tried jumpering power direct to the coil + to see if it will run?

Make CERTAIN the box is grounded. "Wiggle" test related connectors, the bulkhead, the distributor pickup, the ballast, and the ignition box connector
 
TrailBeast said:
Check for power with your test light at the steering column connector (key off)
If none take a look at your amp meter connections.
Those sometimes melt and disconnect your main dash and ignition feed.

FYI, with the factory ignition box and coil you can disconnect the plug for the distributor, and on the harness side touch the exposed metal contact to ground and you will get one spark per ground touch.
(That way you don’t have to keep cranking it for testing)
Click to expand...
So I unplugged the ignition switch and checked the harness from the bulkhead and I couldn’t find any power. So how would I find the amp meter connections. I keep googling where **** is but i can’t find it. Apparently 74 was the wrong year to buy hahahah
 
Part of the 73 manual may help you but be aware "could be" differences. And over at MyMopar there are simplified aftermarket diagrams that are two pages. These leave out options and details sometimes, but can be easier to follow.

This page

Wiring and Electrical – MyMopar

mymopar.com mymopar.com

Hit "Mopar Wiring Diagrams"

Wiring – MyMopar

mymopar.com mymopar.com

and download "save as" the 74 link which unfortunately has been changed, and bundled into a zip file. You have to unzip it and pick the two correct pages

Generally speaking the ammeter circuit did not change all that much (perhaps specific wire colors and bulkhead connector terminals, etc) You can see the simplified path in this diagram from the MAD article about the ammeter


amp-ga18.jpg


Generally you have a fuse link (74 may have several) off the starter relay stud, which feeds the large red wire through the bulkhead connector and runs to the ammeter. Through the ammeter, and out of black, that big black runs a few inches to the factory welded splice, which branches off to feed the ignition switch input, the headlight switch "headlights only", branches off to feed back out the bulkhead and to the alternator output stud
 
Don't work yourself into confusion. Think about what is common. If the headlights work, you are getting battery power through the bulkhead, through the ammeter, and into the passenger compartment. If anything works in the key "accessory" position, the key switch is at least "receiving" power from the ammeter circuit/ bulkhead.

Does anything work with key "in run"? Gauges? warning lights on the cluster? If so, power is at least getting that far. Next see if power is making it out through the bulkhead to the ballast resistor. That wire splits and feeds the blue wire going to the alternator field (There are two, green and blue)
 
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