No spark and constant 12v at coils? Help!!
 

Just installed a rebuilt engine in a 93 fd tt manual import. It's standard with no alarm. It will turn over and it's fuelling but there is no spark. I have tested all wiring between cas and ecu, and wires between ecu and coil pack and transistor and all are fine for resistance with no shorts or breaks. If I unplug the 4 wire connector to the coil sub harness there is 12v to the blue/white wire and no voltage to the other 3 wires. When it's all plugged in there is a constant 12v to all coil connections.this does not change when the engine is cranked. Just a constant 12v all the time to the coils whenever the ignition is on or cranking. Where do I go from here?! Tried checking the cas signal at ecu with voltmeter but I have heard conflicting info on what figures I should expect? Any input? I am thinking that the coils are fine but for some reason either the ecu or cas isn't sending a signal to drop the voltage to induce ht signal. Does that make sense? There is also a possibility I have hooked something up wrong but it's all factory connectors so it should be ok. Also I have checked coil grounding. All fine. Ideas appreciated. Thanks

I'm fairly sure you will see 12V on all coil input wires with the coils plugged in and the key on, as the ECU tells teh coil to fire by going low.

It sounds as though you aren't getting an RPM signal. You'll need to use a scope to check for a signal at both VR sensors. A voltmeter won't do it.

Thanks for the update. I have jumpered a 12v signal through a all resistor to the trigger from the ecu to the igniter for the leading coil. This provided a spark so I'm happy to eliminate coils, ht, grounding and igniter issues. Definitely a trigger issue of some description. Although not highly accurate I have put an ac voltage check on the disconnected cas as it is an ac trigger system according to the expected waveform in the factory manual as I currently have no access to a scope. I got a 1v signal ac while cranking from the ne side and around 0.1v on the crank angle n signal. Seems to correlate as best it can. All wiring to cas is fine. I'm currently suspecting ecu issues and can get an ecu cheaper than the use of a scope so that's my next step. I am Also working on borrowing a scope. I'll keep you posted. Thanks for the reply