I hate to start off on a forum by posting a question, but I am at a loss and hope someone has some insight.
I have a manual 1996 Corolla DX 7afe with 267k miles. I was teaching my friend how to drive stick when it died. He was holding approximately 5k rpm and just started to let the clutch out when it died. I was staring at the dash when it happened. The tach dropped to zero as if you turned off the car (did not match engine speed).
It turnes over properly when trying to start. Battery voltage is ~12.49v
I've been diagnosing the car and this is where I am at. I figured out 4 problems spanning several areas.
1. Cannot read computer codes,
2. No fuel pump operation
3. No spark
4. No injector pulsing.
Many things would cause lack of spark and injectors, fuel pump operation and lack of codes are simpler.
I've diagnosed the entire EFI relay and fuel pump circuit, it is all working, including connection with the ECU. (Ground the green/red wire at the ecu during "on" and the fuel pump kicks on.)
ECU is receiving power and has ground across all stated power and ground connections in the wiring diagram.
The first 2 issues have me stumped. I wish I had a logic block diagram of the ECU to determine if there are any preliminary system checks which would prevent it from pressurizing the fuel system.
It is my understanding that if you have power and ground at the ECU, you should be able to read codes. Code reader has worked with this vehicle in the past and does work with another vehicle presently. This leads me to believe the ECU is fried. I replaced it with another one (granted, from a rather reputable dismantler) and same issue (nothing).
Usually when you change one element of a system and get the exact same results, that was not it. But what are the chances of a bad ECU (slim) AND a bad replacement from a working pull (slim again).
I also cannot think of any failure modes of components on the car which would fry an ECU.
Any thoughts would be appreciated.