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Discussion Starter #1
In shorter words... ive done the 7m swap a while back. Had it wired at a professional shop. Ran and drive fine. Decided I wanted more power. Took that engine out, replaced all moving parts and sensors, rebuilt the crap out of this thing. Put engine back in but had a hard time trying to find a harness, grey plugs, piggybacked into AEM ecu from driftmotion. I firstly speculated this harness could be an issue due to some wires missing clips(a couple temp sensors and distributor connector was messed up) and some wires, the coating was hardened and brittle... however... im not so sure.
So the problem, no power to b+ or anything from diagnostics port, now.
A few days ago I had power to many parts in this port. Went to turn it over(forgot to plug in distributor to coil wire) after a few attempts of nothing I tested the diagnostics port again. Nothing. Few days goes by I realized the 7.5a fuse in the drivers side kick panel was blown(the one for all the warning lights and things). When I pulled that fuse my door chime turned on.. heres a few other things.. efi main relay in engine bay has power to only one port. Not 2. Trying to figure this out. I had to revamp most of the ground wires and even added several(I had a few grounds with over 233 ohms at first) I still think grounding could be at some fault. Measuring ohms i think I've gotten all of them 3.0 and below.
Moral of the story, im trying to get power to the harness to be able to fire. If I get power to harness the proper way, I should be good from there. This one is really stumping me.
I'll send some pics hoping for a little help. I searched and searched and searched I cannot find any answers... thank you in advanced!
15467
also noticed my opening circuit relay was kinda damaged but has continuity in 3 tabs.
15468
trying to identify all clips here besides the ignitor stuff. Hoping that'll help.

Any help would be fantastic! I can post more pics and im pretty knowledgeable but man I'm confused
 

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MDC What yr Supra??
 

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You need to get the EWD Electrical Wiring Diagram manual for that yr Supra...
 
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MDC What yr Supra??
Oh sorry I forgot to mention that. Its an 84 p-type with an 87 7mge modified to turbo. Was running before the last swap. Just really confused now. I have tons of diagrams but still not getting whats going on
 

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... Few days goes by I realized the 7.5a fuse in the drivers side kick panel was blown(the one for all the warning lights and things). When I pulled that fuse my door chime turned on..
Sounds like a short to power... you'll have to track that one down working your way back to the short. Do you know about how many amps? The exact designation of the fuse and its location could be used in helping determineing the location of the short.

Otherwise I would begin with the battery and work your way towards the battery junction box then to the interior fuse panel, making sure the ground from body/frame to engine to battery is secure and free of corrosion. Unfortunately with a car that's 36 years old even looking into the wire harness can cause new problems due to brittle wires and clips.

2c

will
 
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+B is power from the EFI main relay and is triggerred by MREL by the ECU on the Mk2 X connector. Considering there a million ways to wire a swap I don't know how when can help you over the internet here.
 

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for a 87mge at diag connector, [ pin #12 (BLK/RED) power 12V ] , [ pin #3 (BRN) ground ]

pin#12 at diag connector comes from ECU pin #13 (again BLK/RED) should be noted that this power wire branches off at several locations.
 
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Discussion Starter #8
Sounds like a short to power... you'll have to track that one down working your way back to the short. Do you know about how many amps? The exact designation of the fuse and its location could be used in helping determineing the location of the short.

Otherwise I would begin with the battery and work your way towards the battery junction box then to the interior fuse panel, making sure the ground from body/frame to engine to battery is secure and free of corrosion. Unfortunately with a car that's 36 years old even looking into the wire harness can cause new problems due to brittle wires and clips.

2c

will
15480
this was the fuse that blew on me after I originally had power to the diagnostics port.
And thank you very much for the info, ill start back tracking this fuse/wires to see where they end up to where I have no power again in harness.
 

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Discussion Starter #9
Ok thanks a bunch guys. I'll take all this info and start the testing/checking. I didn't know where else to turn was hoping to drive my new build before it gets nasty here in ohio this year lol
 

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At first I originally thought I forgot to plug something in from the harness to get power. I have one plug(3 wire yellow connector that power goes to starter, and a blue/red wire and a yellow I think yellow/red maybe that has no clip on it but has power) and I thought that was all I needed for power to the harness. I was told from some other mechanics most cars get their power to the ecu from the starter. Assumed this applied here as well. But not sure what the other 2 wires went to originally, still looking into this one.
 

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Well the 7M powers the ignition and fuel injectors with switched power thru the B1 connector on the engine harness in the glove box. How someone wired that into a Mk2 is going to be different depending on who wired it. You have to do some rewiring on the COR and main relays when you do a swap. The 7M engine harness pulls relay connection thru C1 IIRC at the fuse box. The Mk2 runs up thru the dash. Most people just connect the Mk2 starter wires and its just wired separately of the ECU. You turn the key the starter turns. The other wires are back up lights on a manual car. You really need to have the EWD for both cars so you can figure this out. Otherwise your just driving with your eyes closed.

I would just go back to what you had when the engine ran. You're compounding your problems with a new engine and whole bunch of work on top of bunch of other changes.
 

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Discussion Starter #12
Little update if anyone's interested.. so few things I found strange, still no power to the second pin in efi main relay port. Alternator has(blk 3 wire plug on back and top main power wire) 12v power into all 4 wires. On charge fuse, open, I have the normal 12.4v or something then with fuse in place I get 1.89v... so im wondering if the alternator could actually be shorted out. According to the diagram it looks as if the alternator sends power to the 7.5a "warning" fuse at kick panel. That fuse was blown after my first initial attempt at starting it. Is it possible the alternator could have shorted out and maybe thats where I'm not getting power?
15545
15546

This is where I think the problem area is.
 

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Interesting Thanks for the update!!
 

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Discussion Starter #14
a guy previous had wired in the old 7m(pro shop) but there, as it looks like, only 7 wires he cut behind glove compartment. Tapping 3 wires with power, I can tell that one is the COR, EFI main relay, and main relay on passenger wheel well area. The 4th wire with power has only 9v running through it. The other 3 have no power, one was pink, blk/orange, blk/white, and another blk one. It'd extremely appreciate the help because the dude charged me $1500 to hack these wires to work. Also im running a fuel pump from switch(cell and ho pump ran by its own). Any help would be super greatly appreciated. Thx!!
 

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Discussion Starter #15
Idk why it didn't post my other post, but I was reading up on the 7m swap and I know whats going on now. I read over junkies write up but can't, for the life of me, figure out where the "u" connector is. I feel it would help.
 

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Discussion Starter #16
So I chopped and spliced these for testing only. This is where he apparently had the car running. It looked as if it was all wired into the b connector. Another issue. I think these "ecu pinouts" are incorrect. I plug 12v power to +b behind there and get 0v in diagnostics port. However I get power, .84v in in Vf port.
Theres only 7 wires so where's the issue? Lol
 
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