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Basically Stock
2009 GS Turbo. 2006+2007 GT
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Discussion Starter #1 (Edited)
Hopefully someone has an answer for my really obscure problem I've been troubleshooting.



So I just did an engine swap, and now when I turn the key to "On", power is alright. The ECU is getting 12v, ECU grounds are good, body grounds are good, trans ground is good.

However, when I turn it to "On", the fuel pump does not prime, the throttle body/injectors do not make their clicking sounds, and I have no signal at the OBD port.

The starter does not engage when I turn the key to "start". It does however cut power as it normally should. The starter has 12v constant (key on or off), and the signal wire to the starter never gets any signal.

I can't imagine the ECU would have gotten fried, as I did nothing different disconnecting it this time than the other 50 times it's been unplugged, I checked all the engine bay fuses and all have continuity across them. The check engine light also illuminates when I turn the key to "On"

I think I can also rule out immobilizer, as the motor should still turn over, just with no spark when that's the case. Also my door locks still work from the key fob.


Thoughts?
 

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283 Posts
I had a *very* similar situation with our Eclipse when we first bought it. It was the immobilizer not being detected by the car. Very similar clues: no fuel pump prime, no injector noises, but door unlock from the key fob still worked.
 

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Basically Stock
2009 GS Turbo. 2006+2007 GT
Joined
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6,054 Posts
Discussion Starter #4
It's weird that mine would just suddenly not work after swapping the motor, but was fine sitting through the winter without being turned on a single time (winter meant 7 months, actually. It's been cold)


Wasn't yours able to turn over though Josh? And you had an OBD connection still?
 

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Basically Stock
2009 GS Turbo. 2006+2007 GT
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6,054 Posts
Discussion Starter #5 (Edited)
MFI relay-ECU is giving 0.5v. Not sure if it's supposed to be 12 or 0.

That's with the key on. All the ECU power points have 12v. The switched 12v off the ignition is 12 when in start, 0 when not. So I don't think my ignition is busted.

All ECU grounds are under 1 ohm, measured at their plugs. All the grounding points on the chassis have sub 1 ohm to the battery as well.

I tried forcing a communication with the ECU (same way you would for a bricked ECU) and still got nothing. So either my ECU somehow died in the swap, or there's witchcraft. I don't have a spare to test with either.


EDIT: So I found that the starter switch in the "on" position triggers the MFI relay to bridge, which then should give 12v to the ECU. I only got 0.5v in the on position. Gonna test it tomorrow.

 

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I don't know much about cars, but this REALLY seems like a fried ECU. I watch a lot of tuning youtubers and this has happens quite a few times with engine swaps and I'd say 85% of them were fried ECUs.
 

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Basically Stock
2009 GS Turbo. 2006+2007 GT
Joined
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6,054 Posts
Discussion Starter #7
It's just strange though. Nothing I did to the ECU was any different than any other time I've unplugged the ECU. The only change this time is that the wiring harness came out of the car as well. Unless it's a BUS line, nothing seems broken except the MFI input of half a volt. It's like a corroded relay.
 

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Basically Stock
2009 GS Turbo. 2006+2007 GT
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6,054 Posts
Discussion Starter #9 (Edited)
Which one?

Also, MFI relay is not getting 12v at either the switch side, or the load side. So whatever supplies that isn't getting power... Trying to find which pin on the A-15 connector
(main engine harness plug) is for the MFI power. The manuals aren't showing that it's ignition related at all if the ECU main power and battery backup power lines are at 12v. Starter circuit gives those 12v to the ECU, not the MFI

UPDATE: Entire relay bar has no power. It looks like maybe there's an inline fuse in the wiring. Gonna pull the shielding off when it's not pouring crazy rain and test out a theory. Maybe that's "fusable link #9" or "#1". Both are coming up as possible options
 

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Basically Stock
2009 GS Turbo. 2006+2007 GT
Joined
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6,054 Posts
Discussion Starter #10 (Edited)
UPDATE: I earned myself a beer.

I jumped the MFI relay off the battery, and the ECU fired right up with a p0113 code.

I then jumped the starter relay output off the battery, and the starter kicked on. I bet I could have had the car turn on at that point if I held the starter going. I definitely just need to find why the relay box isn't getting power, then it'll run!


Next step, Chris's suggestion of the ignition switch! Gonna see if it's not giving power on the relay box output. It definitely is giving ECU power though. And ACC power. Combined with the IAT high voltage code, it's making me think there's a short between the ignition switch and the relay box though. All 3 relays in that box have no power to them.
 

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Basically Stock
2009 GS Turbo. 2006+2007 GT
Joined
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6,054 Posts
Discussion Starter #12
Problem solved. Some pins on my main harness connector weren't getting contact.

The most obvious problem ended up being it.



Now I have to tap the gas for the car to keep running. A familiar problem, happened last time from a tune issue. So I'm not too worried. I have the wrong file in right now, just waiting on Michael to send me a copy of what he made when we met up.
 

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Hey Sabertooth, mine is doing the same thing this morning, no crank no start but all lights come on, horn works. I just took it for a wash yesterday, started up no problem. I haven't done a tune or anything, would you have any idea what it could be?

Sent from my SM-N960U using Tapatalk
 

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So I just needed a new battery, it was holding a charge but not enough cranking amps from what I was told by workers at Autozone and Pepboys. Got a Bosh Premium, 3 year full warranty, 5 year prorated. Thx again


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