Ignition issue

[Kendog 170]

So, my ignition is acting up. Seems to start a couple of times but mostly won't now. I do Have Halifax's Electronic ignition book and plan to diagnose this weekend but the one thing it does do is fire once when I turn off the ignition. Just curious if anyone had that symptom and what it was. I do have 12V at the + coil and 1v at the - side. I've tried and spare good ECU and ballast. I also hotwired the coil briefly. No one around to check Ign. voltage while cranking. Currently, until proper diagnosis maybe a bad wire connection or Ignition switch. Took it for a test drive after cam change, then parked it outside now can't get it in the garage to work on .

 

[dr dodge]

I would check that everything is grounded good.
when I was wrenching, I had my "ground harness tester"
it was a jumper cable clamp, and about 10 16ga wires with a bunch of various sized big gator clips
jumper clamp to battery -
then I'd reground everything and if it started, then one at a time remove the small grounds till it quit
70% of all my wire repairs were grounds issues

 

[Kendog 170]

My ECU is grounded well. I can check my firewall ground.

 

[dr dodge]

My ECU is grounded well. I can check my firewall ground.

think about anything messed with when you did the cam
dist was pulled, main ground, etc

 

[Dana67Dart]

Some things that come to mind

The ignition switch has E terminals required to start and run the engine .

1. IGN 1
2. IGN 2
3. S

IGN 1 US the run cir, it provides 12v to the one side of the ballast and to the ECU while running (when the key is in the run position)

IGN 2 is the ballast bypass, it provides 12v to the coil side of the ballast and power for the ECU during cranking.( When the key is in the start position)

S is the starter cir, it provides power to energize the starter relay (when the key is in the start position)

The description of the engine firing when you let off the key while starting is typical of a bad ignition switch. BUT there are other things that can do that too.

Get:

1. Pull the yellow wire off the starter relay
2. Get some test leads and hook your volt meter between ground and the pos terminal on the coil.
3. Position the volt meter where you can see it from inside the car.
4. Turn the ignition key to run, you should see near battery voltage on the meter.
5. Turn the key to start and you should see near battery voltage on the meter
6. If you don't see near battery voltage in the run position look at the ballast
7. If you don't see near battery voltage in the start position look for the IGN 2 wire to be attached to the ballast on the opposite side as the IGN 1 wire.
8. If that wire is correct then look at the starter switch.

There is a lot more diagnoses to be done so unless you have known good parts for shotgun by buying new parts. Do further testing to find the reason

Get a remote starter switch. Pull the yellow wire off of the starter relay and put the starter switch between batt plus and the terminal on the relay the yellow starter switch wire was attached to.

Find the wire that feeds the ECU 12v and jumper from there to the battery plus

Jumper from the battery plus to the coil plus.

Use the remote starter switch to crank the engine

If it starts you know it's in the wiring. If it doesn't it could be mechanical or the ECU/pickup/dist cap/rotor/wires/plugs

 

[MadScientistMat]

Is this a stock Mopar type electronic ignition? If not or if there are any mods whatsoever, let us know just what you have.

A stock ignition shouldn't have 12 volt at the coil positive terminal with the key on and engine off; there should be a significant voltage drop across the ballast resistor. Try turning the key off and checking resistance from the positive to the negative coil terminal; let me know what you measure.

 

[1MeanA]

With the electronic ignition it will fire once when you let go of the key even if the reluctor clearance is excessive (ask me how I know). I would check it (0.008" or thereabouts with a brass feeler gauge).

 

[Dana67Dart]

I'm fairly certain that the ECU output to the coil is not grounded with power applied to the ECU regardless of where the reflector is positioned. Its looking for a signal to trigger the transistor it go to ground for the prescribed amount of time to get the dwell it is programmed for. without the signal the coil has no ground and is not charging drawing current through the ballast. One of the benefits of the electronic ignition over points which can stop with the points closed constantly charging the coil.

Well I was wrong about my understanding... the ECU grounds the coil with power supplied to the ECU and only breaks that ground when the reflector passes the pick up and it sends a signal to the ECU.

So seeing an initial 12V at the coil pos and 1V at the coil neg is normal. ( I just tested that, NOTE: as the ballast heats up the coil pos voltage should go down to 6-5 V) If the ballast is bypassed or perhaps the coil is over heating????

 

[AJ/FormS]

If it passes the one-spark test,
AND the ECU is well grounded,
AND both sides of the dual ballast are working,
BUT the coil does not spark while the distributor driveshaft is turning, then there is nothing wrong with any of the parts except the magnetic pick up..... or the pick-up is not being triggered by the reluctor. Either way the ECU is not seeing a trigger. The easy button is to just sub in a known to be good pick-up.
If you have a Dual-Ballast System, with a 5-pin ECU, both sides have to be working cuz the ECU is powered up differently in crank-mode from run-mode. In crank mode the ECU gets its power from BOTH ballasts in series.

 

[92b]

If you have a known good distributor you can plug it in and spin it by hand while checking for spark at the coil wire.

 

[Kendog 170]

Well hopefully I can get at it this weekend. Thanks everyone.

 

[MadScientistMat]

He's measuring 1 volt at the coil negative - this is either grounded (factoring in a voltage drop at the module) or something wrong with the coil.

Stock Mopar modules weren't very sophisticated - they ground the coil by default and briefly un-ground it in response to a pulse from the distributor. It's possible some variants wait to ground the coil until the first pulse arrives, but if the car had one of those, you'd be seeing 12v at the coil negative terminal.

 

[Dana67Dart]

Stock Mopar modules weren't very sophisticated - they ground the coil by default and briefly un-ground it in response to a pulse from the distributor. It's possible some variants wait to ground the coil until the first pulse arrives, but if the car had one of those, you'd be seeing 12v at the coil negative terminal.

I did some testing... and I was wrong how the ECU works (i'll update my earlier post)

I got 1 v on the neg side and less than 12 V (started off at 11 then quickly dropped to 5 as the ballast heated up) on the positive side with key in the run position. I concede that the ECU grounds the coil continuously when powered up.

INTRESTINGLY... with the negative lead off the coil it had 4.5 K ohms with no power to the ECU and 22 M ohms with power to the ECU between the negative lead and ground and 0.1V . So it looks like the coil itself adds to the ECUs circuitry and causes the transistor to switch on making the ground.

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