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No power to ecu

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Old May 24, 2012 | 10:22 PM
  #1  
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Exclamation No power to ecu

Ok just put engine back in the car.

using apexi ecu

no power to ecu no lights or anything comes on the commander, also no lights or anything come on the dash. i have power to the windows, head lights, and blower fan. She cranks over but do to no power to ecu she will not fire.

all fuses have been checked and are good.

any insight would be greatly appreciated!!!
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Old May 25, 2012 | 08:39 AM
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Check all the main wires to the ECU, there are 3 power wires I believe.

1.) Black with white stripe (+12V when Ignition is 'ON')
2.) Blue with red stripe (Constant - for memory storage, always +12V)
3.) Blue with white stripe (Connected to the room fuse)

This may be a grounding issue also.

From here, the FSM is going to be your best bet.
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Old May 25, 2012 | 10:48 AM
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So if there are not enuff grounds it can caus this?
Also what is FSM?
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Old May 25, 2012 | 11:06 AM
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FSM is Factory Service Manual
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Old May 25, 2012 | 11:09 AM
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FSM = Factory Service Manual

My bet is you are missing a ground. There's a couple of shared ground wires in the engine harness that are overlooked sometimes. Review your work and find the power wires for the PFC like stated above to make sure they are hot, too.
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Old May 25, 2012 | 11:26 AM
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ok are there any specific grounds i should check first
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Old May 25, 2012 | 12:19 PM
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all grounds are good checked wires and have no power to any of them
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Old May 25, 2012 | 04:55 PM
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I had this same problem before I attached the grounds that connect to the front crossmember. I forgot about them because they were tucked away and dont even look like grounds. There are a total of 10 but the are connected to buses of 5 each.
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Old May 25, 2012 | 05:04 PM
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Originally Posted by Turk82
I had this same problem before I attached the grounds that connect to the front crossmember. I forgot about them because they were tucked away and dont even look like grounds. There are a total of 10 but the are connected to buses of 5 each.
those grounds are still connected unless there are plugs for them somewhere ells that i dont know about
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Old May 25, 2012 | 09:51 PM
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ok new update.

i get power to everything if i turn the key very slowly and just before the on position it will flash on some times, if turned slow enuf and stopped a hair just before on position all lights and beeping ocker like normal before start up. now as soon as u move it to the on position the lights and all power to the system will shut off and and not come back on till u remove the key and repeat.

this dus not happen every time so i can not get a vid of i

also there is no spark

Last edited by mr209ttrx7; May 25, 2012 at 10:09 PM.
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Old May 26, 2012 | 09:28 PM
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in doing some looking around im starting to think it might be the ignition switch.

i have power to accessories and starter but not in the on position. in looking around it sounds like i have a bad connection on the on switch connectors / pins.

if anyone has any incite on this plz do share
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Old May 30, 2012 | 07:38 PM
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i replaced the ignition switch and main relay checked all grounds and fuses and guess what still nothing
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Old May 30, 2012 | 09:41 PM
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In your original thread you stated you were putting the engine back in. Is the Apexi ECU new or did it previously run the engine before the engine pull? Also, how old is the emission wiring harness?

Steve
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Old May 30, 2012 | 10:24 PM
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emissions harnes as far as i know is original. ecu is new adition to setup along with hks intake and FMIC
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Old May 30, 2012 | 10:55 PM
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Ok, back to original time. Swap out the Apexi ECU for the other ECU (Stock?) that ran your car before the swap and see if it starts the engine. We are gonna fix this. Let us know what happens. From your response, I'll assume a 20 year old emission harness is in place.

Side note: Have you done the required ECU pin-out mods for the Apexi ECU upgrade?

Steve
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Old May 31, 2012 | 06:29 AM
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Originally Posted by mr209ttrx7
i replaced the ignition switch and main relay checked all grounds and fuses and guess what still nothing
Did you test these components before swapping?
Did you test the ones you swapped in?
Have you tested power at the ignition switch that it is indeed getting voltage?
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Old May 31, 2012 | 01:39 PM
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It is a us spec engine not a j spec no need for repin. Engine came out of a 93 my car is a 93. Stock ecu same prob. I have a friends shop chasing wires and doing truble shooting right now bc im freeking stumped.
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Old Jun 8, 2012 | 09:32 PM
  #18  
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ok so just an update we got her running. we pulled out all the diagrams and everything found out there was a single wire missing from main fuse box to secondary fuse box.

ty for your guys input helped alot to rule things out.
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Old Sep 25, 2023 | 10:52 PM
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So did they just repin the harness and it worked?
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