LML standalone harness

Im looking to make an LML bench harness...im looking at the schematics, but wondering if anyone else could check my work.

I saw EFI Connection's LML standalone harness, but it looks like theirs only uses 2 of the 3 connectors. In looking at the schematic, it seems like the LML harness requires all 3 connectors? Or does it? Obviously if one of the connectors has an internally bonded circuit, I would rather just leave off the 3rd connector to make the bench harness less clunky.

C1, pin 48....ignition +12v
C1, pin 73....ignition +12v
C1, pin 26....ignition +12v

C1, pin 67....battery +12v

C1, pin 46....GMLAN -
C1, pin 66....GMLAN +

C2, pin 17....ground
C2, pin 18....ground
C2, pin 21....ground
C2, pin 73....ground

C3, pin 73....ground

This is EFI Connection's harness...clearly only shows 2 connectors, I cant see which two though.

Attachment 17387

thanks
Ben

I only use a single connector on mine, everything you need is on the blue plug, the grounds are all internally connected so there is no need to connect the grounds on C2 and C3, just buzz them back to grounds on C1 and use those. Also, these things pull a lot of current when they first fire up!

I have the EFI Live connection harness, it works fine for TIS files, Ross is correct it wants a strong power supply.

If not the ecm will crash while flashing

Quote:

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Originally Posted by GMPX

I only use a single connector on mine, everything you need is on the blue plug, the grounds are all internally connected so there is no need to connect the grounds on C2 and C3, just buzz them back to grounds on C1 and use those. Also, these things pull a lot of current when they first fire up!

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Alright great thanks Ross. Ill get out my multimeter and see which pins on C1 are tied to ground, and use those.

Ive already "bench flashed" an LML ECM, but that was with an entire full engine standalone harness on the bench. I was extremely surprised at how much current it pulls at startup as well! The in-rush was every bit of ~4 amps, according to my lab-grade bench power supply.

Ben

I have a dual 450W-15A power supply just for these picky ecm's

The EFi Connection does not use the BLACK connector, only the Blue and Grey

Quote:

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Originally Posted by GMC-2002-Dmax

I have a dual 450W-15A power supply just for these picky ecm's

The EFi Connection does not use the BLACK connector, only the Blue and Grey

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Are you using an ATX PC power supply Tony?

Yes,

the 2001-2010 ECMs don't pull a lot of juice, but these do.

I have them tied together so I have enough power.

I almost thought about getting a small battery and leaving it on a minder for enough reserve amps

Also when TIS reaches the end of the flash the ECM resets and if the power supply hasn't got enough juice TIS thinks the flash failed and it starts again.

I'm guessing the large current draw would be the ECM charging the capacitors to fire the high voltage piezo injectors the LML uses?

Yes I would say so, then it detects open circuit injectors and shuts it off.

I have wondered if EFI connections wire gauge is sufficient.

I would say it is fine as there is no actual load on the injector outputs so it is a very momentary large current draw as the caps charge.

Ross,

The 2015 ECM I have is really being picky, I assume the pinouts are the same as the 2011-2014 ? Or is there a CAN+ CAN- Difference ?

It fails at 524928 bytes every time on the bench, any tricks I don't know about since its out of the vehicle ????

Was going to put it in the 2012 and see if an in vehicle flash would work.

???:thankyou2:

Quote:

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Originally Posted by GMC-2002-Dmax

Ross,

The 2015 ECM I have is really being picky, I assume the pinouts are the same as the 2011-2014 ? Or is there a CAN+ CAN- Difference ?

It fails at 524928 bytes every time on the bench, any tricks I don't know about since its out of the vehicle ????

Was going to put it in the 2012 and see if an in vehicle flash would work.

???:thankyou2:

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Hi, did you found what was wrong ?

Not yet

Ross, could you please check which specific pin on the blue connector you are using as ground on your bench harness? Using a multimeter, I found a bunch of pins on the blue connector that are internally tied to ground..........but Im worried that those pins I found maybe are just low-reference circuits for sensors. Since the ECM has a large inrush current when first powered up, I would hate to use the wrong "ground" pin on the blue connector and have it fry an internal ground trace.

An interesting note I found...on the LML ECM, some "ground" pins are also tied to the case, and others arent. I wonder why? On every other ECM I have worked with, everything marked "low reference" or "ground" is also tied to the ECM case. According to the truck schematics, both the "case-grounded" ground pins and "non-case-grounded" ground pins are tied together externally in the wiring harness. But I wonder why they arent tied together internally?

Thanks
Ben

I know this tread is over 2 years old, but a quick question. Do we need to put any resistors on the Can + - to make the 120 Ohm load?

Thanks

Sam

Quote:

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Originally Posted by 30 RUM

I know this tread is over 2 years old, but a quick question. Do we need to put any resistors on the Can + - to make the 120 Ohm load?

Thanks

Sam

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Depends what you will be using to flash it with. I have never had a issue using EFI Live bench flashing. But if you wanting to Tis flash then you will need a load.

Sam generally you don't need to do this on GM ECM"s as they have the CAN termination resistor in the ECM itself. In fact I can't think of one GM ECM that needs it.

Sounds good,

I just wanted to make sure I had everything before making my bench harness. I didn't want to have a CM2350 flash back :grin: .

Thanks

where does one buy the pins for the E86 ecu connectors? Ive been looking around ordered a few different ones from various websites once they get here hopefully I ordered the correct ones. part number 12030453 can anyone let me know if this indeed the correct part. Thanks for any help or advise.

Well I was able to get my hands on a cross reference part number from a local auto parts store today and they are in fact the incorrect pins for the e86 ecu connector, back to square one lol

Check with eficonnection

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Originally Posted by GMPX

Check with eficonnection

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thank you very much!