synman95

Alright this is my first post on here and it wont be my last. Im swapping a dohc in to a 89 manual s13 and having power issues no ecu power no fuel power and no spark but engine turns over . i have swapped the dash plug over to the sohc plug on my dohc harness for some reason i have no power going to my ecu. the light wont turn on at all. I have checked the blue ecu plug and theres no power going to it only grounds. I have triple double checked the grounds for the harness and everything is correct. i have no idea what else to check i have checked all my relays and they work just fine. Any ideas on why my ecu isnt getting power? Im banging my head against the wall lol.

Prince of Saiyans

Did you check for power and ground at all the pins? Print out a ecu pinout and double check. Check all the grounds. I know pin 46 should have power at all times. Even will the key out. If it doesn't check the fusible links in the fuse box. Then pin 47 and 38 are both power. Both are controlled by the eccs relay. Test the relay or jump it with a paper clip and see if the ecu lights up. See if you're getting anything a pin 34 WHILE cranking. Use a back probe for if you have some or a super thin paper clip. You said you check the grounds. What did you check for? Just that they are hooked up or did you ohm them out? Are all your grounds in the engine bay good? I've had a ecu not power up so we ran so a new ground and clean up the old ones. Then it turned on.
Heres the ecu wiring layout. Then just use google for the pinout.

https://nicoclub.com/archives/240sx-...locations.html

When I got my first 240 I downloaded the fsm and went to a fedex print place. Might want to think about doing that. Its nice having it on paper.

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Jfornachon

Find the wires that should have power and trace them back to the battery. Sounds like you have a fuse or a Relay problem.

have a great day,
jared