V1 Build Guide Part 10 - Thinning the Body Harness

[Adam]

Build Guide Part 10 - Thinning the Body Harness
In Part 10 we unwrap the body harness and thin out the unnecessary wires.

 

[RichN]

Is this the time you would remove the ABS connector that goes to the module? Also the small black and purple connectors that go to the wheel sensors?

 

[Lonny]

Yes, but there are some things we need to check before you do.

The data wires that daisy chain throughout the car are likely to go into and back out of that big connector.

Trace the tan/tan black twisted pair of wires coming out of that connector back to their origins and post a picture of them. Lets see if they are data wires.

 

[RichN]

This harness came from my second donor; 2005 LT sedan
2 go to the abs plugs, 3rd goes to that 4 pin, 4th goes to the black and blue multi plug

Row C pins 5 & 6

 

[Lonny]

What plugs into the plug that has the four wires.
Where does the data wires go from there.

 

[RichN]

Those are the only twisted wires left on the main harness; the rest were removed when I thinned out the air bag yellow connector.

4 pin =
Green goes to the rear tail lights.
Brown goes to the big red bcm plug, it is one of 2 thin brown tied together in the center of the plug between the large green and 2 thin grey that have already been clipped.
I followed the twisted tan wires through the black and blue multi plug to the dash harness to the blue and white bcm connector.

 

[Lonny]

In your image there are two sets of data wires coming out of the big abs plug. One pair goes to the big main multi plug. The other goes to a plug with four wires. A green a black and the two data wires.

What does that plug hook to?
We need to see where the data wires go from there.

 

[Lonny]

This shows the complete data path.
Upper middle right - OBDII - start
Upper middle left - ECM - end

 

[RichN]

I cut the plug off so I could identify where it went under the hood.
The 4 pin is on the right, then it goes into the 1st box, then appears to daisy chain over to the box on the left. Only 1 set of twisted tan on that connector.

 

[Lonny]

Cool
When you create your Goblin harness make sure the twisted data wires coming out of the TCM hook to the data wires coming out of the BCM. The pair that go from the BCM to the main multi plug.

 

[GingerAle]

I only made it this far. I need more time to watch every video.

 

[SliderR1]

Can anyone confirm that the twisted data wires are all that is needed to be kept intact from the VCIM module? 2005 SS/SC harness.

 

[Briann1177]

The VCIM should have two pairs of tan and tan/black twisted wires. The incoming pair should come from your BCM. Should be pins 2/3. The outgoing pair goes to your big ABS plug. Should be pins 8/9. That entire outgoing section of twisted wire can go. You'll then extend the incoming pair to meet up with the pair that is connected to your ECM plug.

I hope that makes sense.

 

[SliderR1]

Perfect! That is what I was thinking. Thanks for confirming.

The other two connections can be totally removed, correct? I think they all go to stuff like the rear view mirror (onstar), etc..

 

[Briann1177]

Yep. Other connections can go.

 

[Nilbog]

Got a little snip happy and looking for some assistance as the ABS plug may have gotten me. Onstar part 2 plug: removed the green wire from white connector, and removed the two sets of twisted pairs from their opposite end connection points because i assumed i didnt need onstar capability. But when i realized i need the twisted pairs i now can not remember where they were connected. 2008 Cobalt LT. Based off of what i have read online i believe this is where they were connected.

I have found on the ABS plug that i cut both (in and out) sets of twisted brown/black pairs right at the plug. I also found the black and purple multi-plug below with one set of twisted pair that is a couple feet long and coiled up in picture. The other twisted pair brown/black from the plug in picture goes to the black ECM plug. In addition i found the onstar plug with the green wire and both sets of twisted pair wires all at full length (10+ feet). I suspect the twisted pair from the black/purple multiplug in picture went to the ABS plug. One set of the twisted pairs from the Onstar connector went to the back and blue multiplug and the other pair went to the other ABS connection.

Does this sound right? If so how do i address? HELP Let me know if i can clarify better.

 

[Lonny]

Data wire path as it Daisy chain it's way.

 

[jayrolls]

Data wire path as it Daisy chain it's way.View attachment 4692

Ok so I do not have the connector in this image. Here is what pulled from ALLDATA for the High Speed GMLAN. I have highlighted what I believe is the signal path. I am at the point of cutting the EBCM plug out and want to make sure I get this right. Question: So do I just need to loop wires at pin 36/21 + and wires at pin 37/22 - , to bypass the EBCM and keep the data lines daisy chained?

 

[Ross]

Once you eliminate the EBCM and VCIM modules, the GMLAN wires will go from the PCM directly to the BCM. You will need to extend them, so grab some spare tan GMLAN wire, and solder it in.

 

[jayrolls]

Once you eliminate the EBCM and VCIM modules, the GMLAN wires will go from the PCM directly to the BCM. You will need to extend them, so grab some spare tan GMLAN wire, and solder it in.

Awesome, that’s what I wanted to make sure of.