ECM tan/black & tan High speed GMLAN wires question.

[wallace58]

On my 2007 Cobalt SS SC donor harness I have a pair of comm wires from the ECM plug pins 1 and 2. Where do these tie into the other ones of the dash harness. I do not have the same stuff as in the video. My boost gauge is an early style. I see the com wires for the OBD2 port and EPS connector they all go to the BCM. I am not seeing how the comm wires from the ecu tie into these. I have exhausted all my wiring diagrams and posted pinout photos. Any help would be great. Maybe I am being dense or something, LOL.

 

[Gtstorey]

Your should look similar to this minus the TCM.

High speed GMLAn

on my X101 Body Harness to Engine Harness, I cut out the high speed GMLAN serial data wires during the main harness thinning videos. Is this correct or do we need them? It is the purple 14 pin connector.

dfkitcar.com

or

Ross's extended city, easy entry Goblin- 06 SS/SC, NW Arkansas

Sure like your frame color. Brad Thanks. I’ve heard it’s brighter in person. :oops:

dfkitcar.com

The important part is for every part that you leave to connect together in a chain with the DLC/EPS on one end and the ECM on the other. The components with the 120 ohm resistor should be on each end.

I think the high speed GMLAN wires makes some color changes on the older models as it moves between modules.

 

[wallace58]

So do I tie the tan/black wires at the BCM from the EPS to the C1 wires from the ECM? I would think the C1 ECM wires would go to some pins on one of the BCM connectors of the main harness to BCM. Or am incorrect.

 

[Gtstorey]

You will have to post some diagrams of the stock system. I don't know the older model diagrams or connector call outs. But no. there should be additional data wires coming from the BCM besides the ones for the EPS.

 

[wallace58]

Thanks. I will draw up what I have and run it b y Adam when I pick up my kit on 2/3/23.

 

[Gtstorey]

Basically each module should have 2 pairs of High Speed Wires, except the ECM.

 

[Ross]

So do I tie the tan/black wires at the BCM from the EPS to the C1 wires from the ECM? I would think the C1 ECM wires would go to some pins on one of the BCM connectors of the main harness to BCM. Or am incorrect.

The data flows between the BCM and the EPS on one set of brown wires.

Power Steering, C2, pin 4	brown/white strip	High speed GMLAN serial data +	Goes to BCM, J2, pin 1 (J2/C2 is the white & blue vertical connector closest to the center tunnel)
Power Steering, C2, pin 5	brown	High speed GMLAN serial data -	Goes to BCM, J2/C2, pin 19

The data flows between the BCM and the PCM(GM's name for the ECM) on a different set of tan wires.

BCM, J2/C2, pin 2	tan/black strip	High speed GMLAN serial data +	Goes to PCM, C1, pin 1 (C1 is the blue connector on the PCM)
BCM, J2/C2, pin 20	tan	High speed GMLAN serial data -	Goes to PCM, C1, pin 2

 

[Gtstorey]

.....the PCM(GM's name for the ECM) ....

Actually PCM is one of GM's older designation used in the earlier models. Later models use ECM, and it would surprise me if they haven't changed it again since the latest service manual I have which is 2010.

 

[wallace58]

Got it! The tan/black and tan wires going to dash harness plug that goes to main harness is J plug. I cut them from J plug and solder to PCM C1 pin 1 and 2 wires that are same color. Thanks.

 

[Robinjo]

That sounds about right. During the reconnection phase of the videos I remember only having to extend and connect the brn/blk data wires once.