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Discussion Starter #1
Im wondering... could a power transistor go bad? And if its bad, wouldnt this be a reason why my car cranks and cranks and cranks, but doesnt fire up (cause of no fuel and spark) And if my power transistor is bad, wouldnt it cause my ECU to not have any power going to it? But at the same time, would it cause the rest of my car, like my lights, gauges, radio and all that to not have power?

Cause I was looking through the electrical section of the fsm and saw "power transistor" and didnt know wtf that does or anything. other than has something to do with "power", which in this case, electricity... Can someone also explain what it is used for? and if this could be the cause to my starting problem....

Thanks!


Btw... reason im asking, is because when i bolt my ecu up, my car wont start, but when i just let it lay on the ground, u gotta twist it to the right spot till u hear the relay kick on... and then start it, and if it shifts any, car shuts off... and im not wanting to bs this, i just wanna fix the problem for good.
 

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It sounds more like a short/brake in the wires to your ecu in the main harness.

I'm pretty sure the power transistor is what switches your coil on and off for the spark.
 

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Discussion Starter #3
It cant be... because i have 2 whole wiring harnesses... and both have the same problem... unless... thinking about it... i havent replaced my lower wiring harness... I will just try that next...


BUT PLEASE, KEEP TALKING TO ME ABOUT THIS POWER TRANSISTOR... ABOUT WHAT I SAID IN MY OP.
 

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If we're talking about the same power transistor, and i think there's only one, it in inside the distributor and can only effect coil operation. It would not effect the power to the ecu. I'm basing this off of the Engine and Emission Control Overall System Circuit diagram in the FSM for a 1996 240sx. It's the pdf one from the FSM section on this site. If you have the same, it's page 8 of the EC section
 

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Discussion Starter #5
idk... cause in the chilton manual... it said there is one by some sensor.. and then there is the one on the passenger side of the engine bay...
 

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The only Power transistor I found is marked with the red arrow, inside the distributor. With the ecu in it's "not working" position i would check the pins 1-4 marked with green with the key in the on position. Check pin marked 5 when cranking. Other than that, i'm lost. Good luck
 
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