blackbox19

Working on a stand alone and dont want to send off my computer just yet to have the vats removed.
What kind of signal is the ECM looking for from the bcm body control module?
I know the ignition switch has a resistor value that the bcm is looking for and then when that is good it passes something over to the ECM to let it continue running. I have bypassed the older LT1 1995 engines with a module that generates a square wave at 50htz... But not sure if the 2001 computer has that..

1FastBrick

iTrader: (17)

Since we can turn it off in the pcm with tuning software, we don't typically mess with it any other way.

blackbox19

it would be nice to know though... If anyone knows if its like the older LT1 engine computers.. Or a totally different deal

Wolftrk99

iTrader: (5)

As i understand it and can relay it basically.... The bcm looks for a certain resistance from the switch, which it turns into an electronic code or key, which is sent to the pcm to verify the ok to crank the engine... not the same as the older lt1 controllers which iirc were at least mostly obd1. Just do it through the tune and let it eat!

blackbox19

I know I can have the vats turned off.. What I want to know is what the computer is looking for in a signal.. I am a electronic engineer student in my 2nd year and need a project to show teachers I can do something with what they teaching us. I did the create a square wave processor with a 555 timer. AND I verified my work was equal to the store bought ones on the market to bypass the fuel enable signal on the LT1..
I know I can buy a remote start bypass and do the same with our computers but I also need to know how they work to build a circuit board model that does same.. I may have to buy that bypass and just test its signal output with a service monitor to see what its doing..

That resistance the BCM is looking for is easy to replicate and bypass.
I looked for a FSM that has the info about what the BCM and computer are looking for.. but not able to find it anywhere,.

DrX

iTrader: (7)

The BCM and PCM on a 2001 truck communicate via Class 2/B serial data.

blackbox19

Thanks... You know what they using to communicate with? Is it a signal form or is it like computer coding where there is a series of bits in sequence?

blackbox19

Looks like I will be sending off the pcm ..... Was wanting to get everything installed before doing that.. But I want to see it run before pulling out and making it fit in my project....

At least its cheap to have it done.. Just sucks as I want it yesterday done..

DrX

iTrader: (7)

Serial data will be digital communication (0's and 1's) following the protocols for that particular bus type and those which GM was using for messages back then. Not sure if the password changes with each key cycle. I don't think that the available bypass modules for Passlock actually operate on the digital side of the security system. More likely they are just simulating the signal from the key lock cylinder to the BCM.

blackbox19

serial will be voltage... high and low... which translates to 1s and 0s..
but that is even harder to figure out the correct order..
I guess I will be sending off the pcm to get the vats out... then again later for all the other **** I doing to the car...