Hey all I've hit this common problem. And ive tried many of the common fixes to no avail

No spark on trailing plugs
Tach is dead

Jumped the tach wire from leading and tach works

Checked the spark with a fresh plug outside engine, no spark.

Used a multimeter to test the wiring, all the prongs on the connectors to the trailing coil are getting the correct voltage.

Tried a known working coil straight out of a friends car, didnt work

Tried a different known working coil, still didnt work.

Trailing coil is earthed correctly

Alternator is working correctly.

Spark plugs themselves are fine.

Car runs fine, but trailing is definitely not sparking.


Please help I cannot isolate the issue


Car is a JDM S5 Turbo

 

Did it ever work?

Scope the trailing coil trigger and select lines and verify the ECU is sending a signal.

If it isn't, check the CAS signals. If OK, swap the ECU.

 

Yes, trailing was firing and working fine until it mysteriously stopped


Considering the coil itself is receiving the right voltage etc. Doesnt that mean the ecu is working?

If not how do I go about testing the ecu is sending the signal?

 

Bumping for any new suggestions or clarification

 

The ECU works by sending ground signals. The easiest way to test it is by getting a light tester and put the clamp in the positive side and the tip of the tester on the negative side and have someone start the car if the light is coming on and off and the tester then your computer is sending the signal. If it doesn't start blinking then your ECU is not sending ground signals. Or most likely there is a broken wire somewhere. Hope this helps

 

Yes that very helpful thankyou, so I do this for the wire that sends the trailing coil fire signal? Now I just gotta trace it back! Thanks!

 

Yes between the signal and the 12V

 

You can check the signal by connecting an oscilloscope to the trigger wire.

 

dang! Im having the same issue right now! ill keep an eye on this thread and let you know if I find a solution on my car