I'll try to keept this short...
Engine hiccupped and died while car was running on the last few millilitres of fuel. Figuring it ran dry, I did a roadside refueling... but the car wouldn't start anymore! Not even a little bang or sputter. Seeing as how it completely died instantly and unable to restart at all (not a "loss of performance" or "rough running" or something intermittent), I can't imagine running it dry could have caused this fault. (I accidentally ran the car dry once before about a year ago; had no problems refueling and restarting after that incident.)
So I can only conclude this recent possibly-tank-ran-empty incident must be unrelated, and the actual fault having manifested itself at this same time must have been purely coincidental.
I've been trying to diagnose the mysterious fault now for days, to no success. Any help would be much appreciated.
So far, I've determined:
-ASD relay is fine, fuel pump is fine, fuel rail is at pressure.
-Ignition coil is receiving +12V when ASD relay engages.
-Harness line from ign coil (-) to power module is fine.
-Harness line (for ignition pulse signal) from logic module to power module is fine.
-Analog multimeter needle jumps a little when probing logic module ignition pulse signal (suggesting to me that logic module is fine).
-Onboard diagnostics flashes code 12 (batt. disconn. within last 50 starts) and code 55 (end of reporting) -- No real faults are reported!
Perplexing things, shown by an LED test rig I made (single LED w. 1k resistor):
-Connecting the test LED across the ign coil does not show any light pulses. From this, I was pretty sure (at first) that the power module's ignition transistor had failed open-circuit. But then...
-Upon disconnecting the power module's ign coil drive / pull-down line from the ign coil (-), and connecting it only to the test LED (-) (keeping the test LED (+) on ign coil (+) / ASD relay output), the LED shows light pulses when cranking the engine! (Suggesting to me that the power module's ign coil transistor is actually doing something!)
So is the transistor OK? Or is the transistor "partially-bad" (having failed with super-high impedance) and unable to pull the low-impedance ign coil (-) down to GND? (But can sink a tiny 12 mA to GND to light an LED?)
I read somewhere else the ECU is supposed to throw a code 43 if the ignition coil driver circuit fails ...But no fault codes are being reported!
Any help diagnosing this matter would be much appreciated.