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Discussion Starter · #1 ·
I'm getting an abs error C0245 when I test drive the truck.
So I go ok. Let me start ohming out the connection. all my powers pins 1,4,21 (fuses )
checked to the pins I ohmed out on the ecbm connector and so do my speed sensor ,
torque request and delivered wires. The last 3 all ohm out correctly to my gen 3 pcm.
Grounds also checked. I then went to the Data lines and I'm not getting
continuity. I thought the lines on pin 7 and 16 where tied into pins 15 and 16 that went to the c1,
But I'm not getting continuity on my Gen 3 ECM pins 15 an 14. It's hard to follow the wiring because on my schematics or at least the one I found on the colorado forum , instead of showing the wire all the way,... I
get a box saying DLC systems. I assume those are the data lines. My question is does the ecbm go only to say the BCM C2 (A38 and A39) or is it supposed to go all the way to pins 15 and 16 on C1 originally and I missed something when I rewired the truck?
 

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The Data Bus for the Colorado is different from the Tahoe. All of the Data circuits for the modules in the Tahoe were connected together at splice packs. The Bus in the Colorado goes from one module to another module. I sent you a message.
 

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Discussion Starter · #3 · (Edited)
ok so it looks like I solved my issue. Three test drives later my Dash is dark. No more ABS error lighting it up or cow bell going off..
The problem wasn't with the EBCM or the data line or anything like that. It was a software setting in the pcm. After hours and hours of searching, I came across a couple of threads on HPTuner forum.
It turns out the Vss sensor on the trainny sends it's signal to the ECM. The Ecm then calculates that signal with a couple of programmed parameters and it sends the pulses to the BCM. IT doesn't send it to the ecbm, becuase both of those units have their data lines going to the BCM. My issue was caused because the engine(4.8 ls w/4L60) I swapped into my Colorado ran 17 rims with a different rear diff.
The BCM checks both inputs and if everything agrees....we have Antilock brakes. IFsomething doesn't add up.... it throws up and we get a couple of misleading codes. I say misleading because my code said the EBMC was bad, but it wasn't.
I was also lucky that I have HPTuners because that sofware also comes with a " Gear/tire Wizard" You input the tire size and gear ratio on your diff and it will calculate the correct settings you should have in your "speedometer" table that is in your ECM programming. IT's a really neat tool that I discovered, that without it, I wouldn't of been able to figure out the values. I've included a Jpeg of the values that were adjusted for 15 rims. As you can see the changes were substantial, so that is why my anitlocks were not working.
I now have a gen3 p59 pcm connected to my LSrado with antilock brakes. next mod will be the rotors and bigger tires after I do some other things first.
 

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