No spark after ingition module replacement

-
REVIVER

REVIVER

Active Member
Joined
Apr 14, 2011
Messages
40
Reaction score
1
Location
Florida
Ok Mopar GURU,s

I have a 1973 Duster with a 318, Auto trans. I have the notorious goo running from behind the ignition module. Preventative maintenance dictates a change before failure. Keep in mind the car is running great with this module installed.
I bought a replacement from the local auto parts store and changed it out. Tried to start the car and it just spins with no spark. I took it out and cleaned the ground contact areas and reinstalled it. Same no spark results. Reinstalled the old one and it fires up immediately. Took the new module back and ordered another one. It came in and I installed it, same no spark response as the prior new module. Back to the auto parts store for a new ballist resistor, installed the resistor with the same no spark response. I reinstalled the old gooy one and she fire right up. The old one and both new one's all have 4 pins at the plug. Any ideas???
Thanks
 
The only thing offhand comes to mind is that maybe the distributor is not feeding quite enough trigger power to the new module. In other words, "maybe it is on the edge"

Work the dist. connector in/ out several times to scrub the terminals clean and "feel" for tightness. Inspect the terminals closely with a light, for corrosion

Inspect the interior of the dist for reluctor -to-pickup strike damage, for severe rust and other debri caught/ stuck around the two.

Check the reluctor gap For this you should use a brass feeler gauge. Oh'Really's used to sell these individually. Some feeler gauge kits come with a few brass ones. You need a .008" that is inches not metric

You might also check for grounding. To do that install the new module, turn the key to "run" and check voltage at the "key" side of the ballast, and then the "coil" side of the ballast. "Key" side should have "same as battery" AKA about 12V. "Coil" side should be a lot lower, somewhere between 6-9V. This shows the module is drawing coil power through the coil.......which it is supposed to do under these conditions.

Make DAMN sure the thing is grounded.
 
after that if it doesn't work, get yourself a 3 inch wire with a couple alligator clips attached at each end and jump the wire at your ballast resistor from one side to the other then get in and try and start it and see if it runs. If it runs you have a bad ballast resistor
 
Ballast resister is good as proved by the old unit working.

My bet is the replacement until has pins that are a tad smaller in diameter than the OEM unit. The old connector has lost its tension and is not making contact on at least 1 pin.

You could use jumpers and prove that out. Or you could try to tighten the receiving connectors in the plug.


Lastly. You could CAREFULLY remove as much of the goo as you can and but some "pottant" from amazon

Like this
https://www.amazon.com/dp/B07NDMD2KR/?tag=fabo03-20

But the dp270 requires an applicator gun, but you could rig something up
 
Last edited:
Thanks for the responses folks.
I did replace the ballist resistor thinking it may have broken down to a level that matched the brake down on the old module but the new resistor had the same effect. As far as getting the same one back they had to order it which took two days, the box on the first one was beat up and the second one was in perfect condition and I had sanded the areas where the bolts pass through trying to get a better ground so no chance they gave me the same one again. The engine runs great with the old one in it, thats what is so stange. I have the same thought that the pins are smaller diameter on the new ones and they are not making good contact. I will try and make some jumper wires to rule that out, maybe its time to replace the connector. I am also thinking of ordering an orange box from Summit. I have been reading posts about Chinese junk boxes replacing the good old orange and blue boxes at the parts stores. I am just glad I am tring to replace it while the old one is still working, otherwise I would be chasing my tail bigtime.
 
I recently changed my voltage regulator and the new one was acting very strange. Ended up finding that the terminals in the plug were sprung and not making good contact. Gave them a slight squeeze with some needle nose pliers and it worked great. Your problem may be a similar issue. Also, I always run a ground wire to the ignition module body to the frame. Those sheet metal screws usually don't pull tight enough for a good ground. You can also replace with a regular bolt and put a nut on the back side. You can reach inside the fender well to get the nut on.
 
The other thing you could do is "jig it up" that is get it down to as simple as possible and eliminate as much as possible Some other random thoughts.

1...What is battery voltage and what is battery voltage WHEN CRANKING at the ballast? hook a meter to the ballast with key "in run" (engine stopped) and make sure you have the "key" side which is the highest reading. This reading should be "same as' battery"

2....Clip meter to coil +. Voltage will / should be much lower, perhaps 6-9V. Now crank engine USING KEY while reading meter. Voltage should be "same as battery" whatever that is during cranking, and should be ABOVE 10.5V, the higher the better

3...you can hook a meter to the distributor pickup connector on low AC volts and either spin dist. or crank engine. Distributor should generate about 1V AC

4...Don't guess make ABSOLUTELY CERTAIN box is grounded. To test, turn key to run, make sure coil + terminal is NOT 12V but rather lower, 6-9V This shows coil is drawing current through box, which is correct.

5....Also "rig" a test gap using a solid core wire and gap or spark plug right out of the coil tower. Cranking should give a nice hot blue spark at least 3/8" and typically 1/2" long

6....Pull distributor connector apart, turn key to "run". With your test gap rigged, repeatedly tap the bare terminal of engine harness end of the dist. connector to ground. Each "tap" should give 1 single spark "snap" at the coil


=================================================================
Here is a copy of a post I made some time ago, that is meant to be a help in understanding the hookup and how and why
==================================================================



You need a coil, the ECU and the distributor

Lay it out on the bench. Follow the diagram. Find the two distributor pickup terminals on the ECU. Hook them to the distributor

Hook the ECU case to battery NEG

Coil does NOT need grounded

Distributor does NOT need grounded.

Hook coil + to the power lead terminal on the ECU. Get a clip lead hooked there and let dangle. This is your battery "hot" when you are ready

Hook something from coil "case" to a probe for testing spark.

Hook up your power clip lead. Twist the distributor shaft while holding the test probe near the coil tower. The thing should make sparks

If not, unhook distributor. Take first one, then the other pickup clip leads, and "tap tap" ground them at the battery connection. Coil should make 1 spark each time you do so.

If not, try another coil. If that does not fix it replace the ECU

IF you hook it all up and it WORKS, then there is something AFU in the car harness. SUSPECT a bad ECU connector OR a bad DISTRIBUTOR connector
=============================================
This is all you need to test the basics of the ignition. You can easily test the ballast separate. A battery, the ECU, distributor and a coil, and of course some test leads

2ai0wsj-jpg.jpg


Below, the basic diagram for a 4 pin ECU

166lmj7-jpg.jpg


Below, the wire for testing spark. I use my 12V test light. No, LOL the spark won't blow up the bulb

166lmj7-jpg.jpg


Below, the ground connection. ALL you need is one wire from batt NEG to the ECU case

xawjl-jpg.jpg


Below, the two distributor connections. In the car these are polarity sensitive, but for testing does not matter

b3opvm-jpg.jpg


Below, the coil NEG connection

6jfywp-jpg.jpg


Below, battery PLUS connection, one wire to this terminal of ECU and jumpered over to + side of coil


11lqu5l-jpg.jpg


Below, all hooked up and ready to test (except for battery ground). Should produce sparks at least 3/8" and typically 1/2" long

1zzoya0-jpg.jpg


Below, distributor "one wire" test. I have removed the other distributor wire for simplicity. Take the bare connector end or this clip lead (the yellow) and with everything hooked up, ground it repeatedly. Each grounding should result in a spark (In this photo you need to hook up the ECU ground wire, I left it off for the photo)

vgitld-jpg.jpg


 
Last edited:
OP the other route you might consider is to replace the Mopar module with a 4 pin GM HEI module. The problem with Mopar modules is that they are basically obsolete, so most current replacements are cheap junk Chinese imports.

The GM module basicailly wires up the same as a Mopar without a ballast. You can use a better coil but you don't need to. You do need to mount it flat on a heat sink, and there is a locator "tit" on the heat sink side which must be removed. Many of us run these. I even made an "emergency" version, which I've also used to test fire used engines

I believe TrailBeast came up with this fancy diagram

4pin-jpg.jpg


My redneck "emergency roadside HEI"

You connect to the dist, ground, and battery and off you go

hwlcfa-jpg.jpg
 
do you have a trigger solder gun? I think you can induce a voltage if you trigger the solder gun next to the pickup in the distributor. You should get a spark out of coil gapped to ground or a very faint high pitch buzz from the module but you have to have your ear to it, sort of a 'Bzzzt'. That is the electronic switching. If your old one is working, just repot it with some 2 part epoxy. The potting just keeps the moisture out and retards corrosion. Could even use silicone.
 
WOW, nice post 67Dart273, very indepth. I just placed an order from Summit for an orange box and a new entire harness. 20.00 bucks for a new harness is a no brainer. I will let you all know if changing these fixes the problem. If not I am now armed with your knowledge to track down and kill the gremlin lurking within.
Thanks for the help!
 
Oldmanmopar, I paid 38.00 for the orange box from Summit, 36.00 for the boxes from the local store that are going back.
 
Ok, update as promissed.
The new orange ignition module and harness came in from Summit. I cleaned the paint off the grounding points at the bolts and hooked up the old harness and she fire off immediately. So if you go to change out your module I highly recommend ordering an original orange or blue unit and forget purchasing one from the local parts store! They are confirm junk!
Thanks for the help, you are a great bunch of folks.
REVIVER OUT
 
Thanks for the update. That is the story with many replacement parts not just electrical
 
You must log in or register to reply here.
-

Back
Top