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LSx swap wiring trouble..

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Old May 28, 2012 | 12:47 PM
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Default LSx swap wiring trouble..

Im doing the LT1 to LSx swap using a factory LS1 harness from a 2000 T/A and 2001 Z28 computer. I followed two different wiring conversions ( both matched up perfectly) and can't get the car to start.

First it would just turn over and over, then i fixed the wiring going to the crank sensor, then i got the injectors to pulse but no spark ( have power to all coils) check the wiring to the cam sensor, checked good and when i went to start it again no SES light and pump wont prime, checked the 5v refernce going to the relay and now there is no power.. checked for power going into the computer, still showing over 12v. tried a jumper from another 5v source and still nothing, that connection is also showing no voltage..

Im at a loss on why all of a sudden i have no power leaving the computer, i have tried two different computers and getting the same out come.
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Old May 28, 2012 | 08:12 PM
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over a 100 views and nothin lol, any ideas guys?
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Old May 29, 2012 | 07:26 PM
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????? Help.
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Old May 29, 2012 | 07:45 PM
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When i did my swap i was having same cranking issue with no spark. Problem was my ignition relay was dropping out power while cranking. Applied 12v while cranking fired rate up.
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Old May 29, 2012 | 08:34 PM
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Do you have 12v ignition(key on) staying on at PCM Blue 19?

Did you bypass the Starter Relay on the car behind the Glovebox?
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Old May 29, 2012 | 09:20 PM
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Yes i do have 12v on the key, but did not do any bypass behind the glove box.
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Old May 29, 2012 | 10:26 PM
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I had the same problem you do, bypassed that relay, fired right up.
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Old May 29, 2012 | 11:16 PM
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Ok so after searching i figured out why i wasnt getting the fuel pump and SES light to kick on, so got those back and the starter does its thing but still wont fire up.

Merv if i read your swap guide right about the jumper your talking about isn't it for the starter to engage?

I can smell fuel so im pretty sure the injectors are cycling but no spark, every once in a while it acts like it got a second of spark but wont take off.
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Old May 29, 2012 | 11:24 PM
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Stupid question but do you need the security taken out of the computer to do a swap like that?
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Old May 29, 2012 | 11:27 PM
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I dont think so, my computers are stock but i might be wrong.
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Old May 30, 2012 | 12:31 AM
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Pretty sure you are gonna have to turn off the anti-theft in the pcm before it will start, I'm not sure what it actually disables tho
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Old May 30, 2012 | 01:02 AM
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VATS disables the Injectors. It'll fire for like a sec to give you hope, then die.

As funny as it sounds, it will crank with that relay inline, bypass it and it will start. Don't ask me why.. Just works.

Not saying this is your only problem, but it seemed to be mine, and a few other cars were the same.
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Old May 30, 2012 | 07:48 AM
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Ok thanks man, ill try it tonight and see what happens.
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Old May 30, 2012 | 08:29 AM
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Originally Posted by 94LTZ
I dont think so, my computers are stock but i might be wrong.
THat's most likely the problem though. I had to change the security when putting a 98 LS1 into my 97 Camaro. The BCM has to be relinked to the proper VIN of the PCM, or else it won't send the correct security signal to allow the PCM to enable continuous fuel delivery.
If you have HPTuners, or know someone with a tuning program they can take care of it very easily for you. Here are several links about the VATS: VATS1, VATS Bypass With Resistor.

Themerv's idea is simpler though.
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Old May 30, 2012 | 06:12 PM
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Well got even closer but still not starting, i jumped the relay from pin 30(thick purple wire) to pin 87(thick yellow wire). I tried it with the relay in the socket and out of it with just the jumper wire. It tries to start but just wont take off. Thinking i need to get the computer tuned, i bought it off ebay (12200411) and was told it was for a LS1 Camaro M6 but i just noticed today that the tag that was taped to it said it was from a Chevy truck..

Not sure if DLAC or DFNN means anything on the computers but on computer says-

12200411 DLAC and the other 12200411 DFNN

Thanks.
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Old Jun 2, 2012 | 10:40 PM
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Well it started tonight, i went over the wiring so much i knew it had to be right so i took both my computers to my tunner and figured it out. We found the neither would start a known running car and he tried what he could but came up with nothing but he had a brand new 411 computer on the shelf so we threw a Vin at it for a 01 Z28 M6 and tuned it and deleted VATS.

Was glad to hear it run finally!
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