[nando_dart75]

Hello all.

I have a problem with my 1975 dodge dart special edition; the engine turns over but their is no spark at all, I have run a check on the entire ignition system and have not found the problem, here is the rundown of what I have done:

1.- Ballast Resistor in working order checked w/multi-meter and is within range.
2.- Ignition Coil- in working order but only receives 6.2 volts from the Ballast resistor.
3.- Replaced the starter relay.
4.- Ignition Module checked.
5.- Pick-up coil at 362 ohms.
6.- Battery is outputting 12.6 volts.

I am at a loss as to how to fix the problem, any help would be greatly appreciated, thanks.

 

[motormaker1]

If all is in order, the ballast resistor is by-passed when you turn the key to the start position, so it at the moment is a non-issue in your no-start condition. This is so the coil can deliver a good "hot" spark during cranking. After starting, the ballast will keep it between 7 and 8 volts with the alternator charging system working properly. This keeps the coil from overheating.

The coil can be verified as being in working condition by supplying +12V to the + terminal, and with the help of a friend, hold the coil wire about 1/4 inch from the engine block and make and break a ground connection from the - terminal on the coil. each time the negative wire is taken loose, there should be a good spark. This is best done with it's wires taken loose, but leave it clamped in it's bracket.

I can assume the ignition module was checked at the local parts store on thier tester? That would be about the only way to really verify it's being good. If you were to hold the module's connector with it's terminals facing you, orient it so the tall side of the connector is to your left.

Aint I a good artist? :blush:
You should have 3 terminals on the left and 2 on the right. The left center terminal (1) should have battery voltage with the key on. If not, you may look for a wiring or ignition switch problem. The top left terminal(2) should also have battery voltage with the key on. If not, trace the wire back to the negative side of the coil, as this is the wire that the module uses to ground and unground the negative side of the coil. If you have a dual ballast, there will be a terminal (3) in the top right of the connector. If so, it should have battery voltage as well. If there is a wire, and no voltage, the auxiliary side of the ballast's circuit has a problem. If your module has a single ballast with only four wires in the connector, dont worry.

Your bottom left (4) and bottom right (5) terminals go to the distributor pick up plate. measure across the terminals and you should get about the same reading you did at the distributor plug.

As far as the pick up plate resistance, I have tested and seen them anywhere between the factory allowed 150 to 900 ohms and still not let the car start. Not very often but it has happened.

Hope something I said helped

 

[Bob Lincoln]

2.- Ignition Coil- in working order but only receives 6.2 volts from the Ballast resistor.

Is that with key on/engine off? It should get full voltage during cranking and 6-8 volts when running/ignition on, as stated above.

 

[nando_dart75]

Is that with key on/engine off? It should get full voltage during cranking and 6-8 volts when running/ignition on, as stated above.

yes, with the key in the ON position and the engine is off.

 

[nando_dart75]

Thanks for your Reply, their is 10 volts at al 1,2,3 pins in the connector, and yes theirs the same 362 ohms in the 4 & 5 pins, how would I go about testing the ignition switch? I also checked for continuity in all cables, how would I check for a short in the wiring?

 

[Bob Lincoln]

10v is not considered "battery voltage". Check the battery with key off to see if it needs to be charged up fully before going further. If 10v persists at the battery with key off, you may have a dead cell.

 

[nando_dart75]

10v is not considered "battery voltage". Check the battery with key off to see if it needs to be charged up fully before going further. If 10v persists at the battery with key off, you may have a dead cell.

I get 12.6 at the battery with the key off.

 

[ImperialCrown]

Is the distributor turning while cranking? These had a plastic drive gear that could fracture. The cam timing gear sprocket also has plastic teeth for quieter operation. Is it turning and moving the rockers?
A static test for the pick-up coil (and the rest of the system) was to pass a feeler gauge past the pick-up tip and watch for spark at the coil wire.

 

[nando_dart75]

Is the distributor turning while cranking? These had a plastic drive gear that could fracture. The cam timing gear sprocket also has plastic teeth for quieter operation. Is it turning and moving the rockers?
A static test for the pick-up coil (and the rest of the system) was to pass a feeler gauge past the pick-up tip and watch for spark at the coil wire.

The Rotor is turning, I have yet to check the rockers....

 

[ImperialCrown]

If the distributor rotor is turning then the cam/lifters would have to be also.

 

[rampage]

When you get it let us know what the problem was.

 

[ed1]

i suggest u check for distributor bushing wear causing incorrect air gap between reluctor & pickup coil resulting in weak signal to ECU transistor. :deadhorse:

 

[75devil]

i am experincing the same problem. i am only getting 1.0v to the coil. although the terminal 1 as well as terminal 3 are getting 12.4v from battery also experincing no power to radio and turn the key to the start position the volatgage gauge drops but no crank in order to turn motor over you need to have jumper wire to starter terminal onto relay

 

[ImperialCrown]

The bulkhead connectors at the firewall were troublesome. Make sure that the neutral safety switch is grounding in Park and Neutral if this is an automatic (Bn/Yl). Stick-shift may have had a clutch pedal switch to ground (Dk. Gn).
You may have lost some of the Acc/Ign/Start branches of the ign. sw.
Use a 12 volt test light to trace the circuit(s):

http://www.mymopar.com/downloads/1975/75DartA.jpg

http://www.mymopar.com/downloads/1975/75DartB.jpg

 

[David Eidell]

Make sure you have AT LEAST 10.6 volts at the + coil terminal WHILE THE ENGINE IS CRANKING. You need a friend or a remote start switch or long arms to determine this. I have seen FAR TOO MANY burned ballast resistor TERMINALS, wire terminals to trust "good looking ones" out of hand.

I used to check modules by disconnecting the coil wire at the distributor and placing the exposed terminal within 1/4" of metal. If you get a spark when the ignition key is switched from on to off it is usually a sign the module is not working. I do NOT try and replace a module that has a harness with 5 connectors with a module that has one less pin.

Pickup coils have an annoying habit of failing when they get warm and then coming back to life when they cool down.

 

[chuzz]

You have to make sure your control module is the same as the old one. I had a similar situation with a 73 Polara. The control module that I got from Autozone only had four pins on it and the original had 5. The guy at Autozone told me it didn't make any difference. It DID! I finally found one at Western Auto that had the 5 pins. Plugged it in, hit the key and the Polara was back on the road. If you don't have the correct one, it won't start.