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Richardm140

Help with LS3 Wiring Harness

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Perhaps someone could provide some guidance on LS3 Engine harness wire reduction.

I have a 2009 LS3 engine harness for same engine that was removed uncut.  The donor vehicle had auto transmission.  I have been carefully removing the unneeded wires from the loom without cutting.  I have been using data found on LT1SWAP.com which has been pretty good for matching what I have.  However, I have a few questions that perhaps someone could help answer.

On the MX123 34566 Series connector, Color Black connector
1. Pin 1 is the Park/Neutral Signal - Is this required, for manual transmission install?  If so does it just go to ground?
2. Pins 27 High Speed GMLAN Serial Bus (-) [TN wire] & 28 High Speed GMLAN Serial Bus (+)[TN/BK wire].  Are these for the ODB2 connector (C227 black) or are the for the Transmission Control Module (TCM)?
3. Are the fan wires,  Pin 17 - High Speed Cooling Fan Relay Control and Pin 28 - Low Speed Cooling Fan Relay Control both used, one for each radiator fan?  Or do I just use Pin 17 to drive both fans?  (I know I need relays for the fans).

Lastly are there any recommendations of who could reprogram the ECM.  I would like to have someone one remove the VAT and setup some of the initial parameters.  Then once I have everything installed I would like to get it Dyno tuned to help optimize the performance.  I'm in the Phoenix metropolitan area.

Thanks for any help that can be provided.

Richard

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You don't say which ecu you have .  You don't need the park/ neutral  signal. If you are not using the auto trans, can buss goes to the obd connector. Questions, PM me

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Thanks for the help.  I just have the stock ECU from 2009 Corvette.

 

20190906_081725.jpg

20190906_081752.jpg

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every one does things three own way, the e38 works good with the stock throttle body, as soon as you go bigger you need a super lagit tuner or they just run horrible and will have all kind of throttle pedal codes,

we always change the reluctor wheel to a 24 or use a system like a AEM or MEFI so we can keep the drive by cable,

the other issue I have seen over the last 15 years is so many issue with hacked harnesses and hacked owners,

I always say if you cant afford to do it right the first time how can you afford to redo it,   use a new harness it is worth every penny CBM should have them on the shelf if you are using the factory system,

Edited by J Alper

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If I have the DBW disabled and switch to Cable operated throttle body is there any other inherent problems I would likely see?

Not sure I understand the advantages of the 24x reluctor wheel vs the 58x.  The 58x provides higher resolution of position.  I would think it would be more about compatibility with the ECU. 

I do like the savings and knowledge gained by doing the work myself.  Kind of funny line you had there about "issue with hacked harnesses and hacked owners,"  Learning has to come from somewhere. 

 

I have seen plenty of LS engine running the reprogrammed stock ECUs.  I would think that even a MEFI or other aftermarket would need some fine tuning after the base tune was applied.  Not really sure if the Holley self learning ECU needs fine tuning.

 

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I have seen the hacked harness just wired wrong, have seen the hacked harness, catch on fire, or burn up sensors, or not wired correctly to injectors and lean out a motor, had one that eat 3 ecms, before I told them to get the car out of hear or an new harness,

the e38 can only be drive by wire only,

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Yes a 58x reluctor will provide the ecm more resolution to determine crankshaft position but the reason GM did that was for better misfire recognition for the tighter emission standards which later engines had to meet. A 24x reluctor works just fine for anything you'd want to do with it. 

Holley self tuning EFI is exactly that, self tuning. I have the Holley Terminator on my car and it works very well. I did have to tweak a single fuel parameter to eliminate a flooded condition on a hot restart but to be more open about it, I use a conventional intake manifold and Holley's EFI throttle body on my LS, not OEM port injection. I have done nothing else to it. 

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The E38 does not support manual T/B.  It is set up for 58X only.  Any shop with EFI live, or hp tuners will be able to turn off vats and tune that system. Steve

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Are most people running with a mass air flow (MAF) sensor or do you opt for air density calculations and put in an Air Intake Temp (AIT) sensor?

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IAT sensor here. 

But I have a supercharger and there was a sensor there. 

I had a MAF when I was N/A. 

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