stilllearning6

1989 Dodge Dynasty LE 3.0 Liter:
Strong crank, but no spark.
Ignition coil has continuity in its own internal primary 12v circuit.
No spark / no juice produced from secondary circuit .

I cannot detect a 12v supply to the ignition coil primary circuit terminal.

Disconnected both primary circuit terminals of ignition coil and polished both connectors/wire ends , both primary terminals.
Still no 12v with key turned to ON , not to the crank position.
Why?

What is upstream of the 12v supply wire to the ignition coil primary circuit?
Is it just the ignition switch?
Any connectors? Fuses?

stilllearning6

add'l data:

I just bypassed the AutoShutdown Relay with a paperclip.
The radiator fan motor turned on immediately.
I turned key to ON , not cranking position.
I probed both sides of the ignition coil primary circuit terminals with 12v test lamp--> result no light.
I still do not get 12v to the ignition coil.
It is my understanding that one side of the ignition coil should receive a constant 12v when key is turned to just the ON position, and the remaining terminal of the ignition coil should pass the 12v to the PCM/ECM.

Then, when a 12v test lamp is probed into this second side, the test lamp should flicker as the engine is cranked and the 12v is supposedly passing thru the ignition coil. The intermittent OFF period of the test lite would be under the On/Off control of the PCM/ECM as the PCM/ECM will intermittently ground/ interrupt the ground of the primary circuit .
Is my understanding correct?

Still do not know why I fail to detect 12v to the ignition coil primary terminal?

dodgem880

Hello

I think you should try to get a hold of a electrical diagram for your vehicle application.

I found a block style diagram on AutoZone's repair section.

https://www.autozone.com/repairinfo/...00c15280268885



Well, I have limited experience with computer controlled engines nor am I familiar with your vehicle model but, I'll give it shot.
Here we go.

It would appear that the main power for the ignition coil, fuel injectors and fuel pump is provided by the ECM control relay labeled "auto shutdown relay".

It would appear pin 19/wire black-grey on the ecm is used to trigger the coil to fire. Pin 14-16 are used to trigger the fuel injectors. They all should be ground triggers I believe.

You said you bypassed the auto shutdown relay? Is one side of injectors hot? Can you hear the fuel pump prime?

I'm not sure why the cooling fan started running, it appears to be controlled by a different relay which is also ECM controlled (pin 31 I think?)... so I guess your ECM is trying to do something at least.

All the dark green-black wires should be hot when the auto shutdown relay is closed or bypassed. Is the red feed wire the relay switches hot? try poking it's terminal in the relays socket with a tester light. If it's dead I would check for a blown fusible link or bad connections/wires.

If the tester light works I would next suspect the dark green-black wire. Especially if the injectors aren't getting power either. I'd checked that wire and it terminal connections upstream of the dead devices.

I hope you find this helpful.