Bcm Programming?

[lcorrell]

Background: I recently purchased a non-running 2003 Chevy Silverado 2500HD 4x4 ext cab with the 6.0 and I've been working to diagnose the problem. I have no signal on the Class 2 serial data line, thus no communication with a code scanner. Following the troubleshooting steps I have isolated the BCM from all other modules on the data line and still have no communication with the BCM. I have checked the wiring for opens, shorts to ground or power, or high resistance and the wiring seems to be fine. So the next step in the troubleshooting procedure is to replace the BCM. GM dealer wants $257 for a new BCM and minimum $90 charge for programming it. Says I have to install the module then bring the truck in to be programmed.

 

Now the questions: If I buy a new BCM through GM and install it, will the truck start and run off the blank un-programmed BCM so I can drive it to the dealer for programming? If that won't work, I can get a used BCM for $75 - will the truck start and run off the used BCM with non-matching VIN (after passlock re-learn)? Can the used BCM then be re-programmed at the dealer to have the proper VIN info and match my truck?

 

Thanks for any help.

[Robert5168]

Thank you so very much for your help, it is greatly appreciated. I agree with you about the software issue. It would appear that we own our vehicle but not the software. Something needs to be done as this will greatly limit what type of problems we are able to repair. If you vehicle is over five years the dealer does not like to service it.

 

I was accused of hijacking your thread, as this was not my intent so I apologize to you. Just looking for help. Thank you for your reply and updates. I will let you know if I am successful .

[jbelman]

I'm just following the diagnostic procedure in my repair manual. It says the bcm is the Power Mode Master (PMM) and controls all other modules including the pcm (on my truck anyway).

I think your manual is for a newer vehicle, power mode mastering was not used on chevy trucks till 05-06.

The wiring diagrams show there is no direct link between the pcm and the diagnostic link connector, it shows the pcm connects directly to the bcm which then connects to the dlc.

That is the second clue that the manual is wrong. The diagram should show the bcm and pcm in a loop to a splice pack then to the dlc. The way your truck should be wired is that the bcm and pcm are wired togeather then they have independant circuits back to the dlc so that either module can communicate with the scan tool independant of the other.

The bcm is what receives the ignition switch signal and sends out the signals to all other modules to activate. So if the bcm is dead and sends no signal to anything, the truck would not start. Which means the bcm is what is preventing my truck from starting - according to my repair manual.

Again on an 07 this would be true but not on an 03. The truck will not start without the bcm because of the security but it does not send out the on signal for the other modules like a new one would.

 

Believe me, I've been all over this truck checking things and testing. At this point my next step is to replace the bcm. But, I need to know about programming the replacement bcm as I asked above to know what to expect.

I have three possible scenarios: All that said if you still want to go with the bcm I'll tell you what I know. You could get lucky and need the bcm but I wouldn't put money on it (which you are).

1)I buy a new replacement bcm from my gm dealer, install it, start the truck and drive it to the dealer for programming.

 

You could do this, you will have to program the security code first. Then drive it in to have the RPO's programmed in the BCM.

 

 

1 Turn ON the ignition, with the engine OFF.

 

2 Attempt to start the engine, then release the key to ON; the vehicle will not start.

 

3 Observe the SECURITY telltale; after approximately 10 minutes the telltale will turn OFF.

 

4 Turn OFF the ignition, and wait 5 seconds.

 

5 Repeat steps 1 through 4 two more times for a total of 3 cycles/30 minutes; the vehicle is now ready to relearn the Passlock Sensor Data Code and/or passwords on the next ignition switch transition from OFF to CRANK.

 

Important: The vehicle learns the Passlock Sensor Data Code and/or password on the next ignition switch transition from OFF to CRANK. You must turn the ignition OFF before attempting to start the vehicle.

 

Start the engine. The vehicle has now learned the Passlock Sensor Data Code and/or password.

With a scan tool, clear any DTCs, if needed. History DTCs will self clear after 100 ignition cycles.

 

2)I buy a new replacement bcm from my gm dealer, install it, the truck won't start, I have it towed to the dealer for programming.

Follow the above and you should be able to drive it in.

3)I buy a used replacement bcm from the salvage yard, install it, start the truck and drive it to the dealer for programming.

You can try this and try the above but I wouldn't know if it would work or not. All year, make and model bcm's are a little different and without trying this on your particular make and model. If you can get the security to work the RPO's might not be able to be programmed, it's really just trial and error with this method.

 

I'm just looking for info from someone who knows for sure which of those scenarios is realistic.

 

Thanks again

I purchase a 2006 silverado 1500 crew cab 4x4 - recovered from theft, it was missing BCM, I purchase it from wreck yard and follow this steps, and it work !!! Thank you very much for all this people that take the time to help others... quick NOTE: on step 3,, make sure it gets off, because at 10 mins aprox it stops blinking but few seconds after it goes off.

 

Thank you very much..

[jbelman]

I purchase a 2006 silverado 1500 crew cab 4x4 - recovered from theft, it was missing BCM, I purchase BCM from wreck yard and follow this steps POSTED BY ((sparkstech, on 21 Aug 2010 - 07:44 AM, said:)), and it work !!!

Thank you very much for all this people that take the time to help others... quick NOTE: on step 3,, make sure it gets off, because at 10 mins aprox it stops blinking but few seconds after it goes off.

Thank you very much..

[SpartanAutoworx]

Using a used BCM You will have to unlock the Radio. Nav units can be done with a good scan tool or the tech2. The Uplevel RDS Radio will require SPS. If you have a 2005 or newer you will need to reset the SDM via the Scan tool. 03-04 the 30 min relearn procedure will reset the restraint ids.

 

You will find two styles of BCMs in use on the 03 up trucks and SUVs.

 

Reg Cab / Ext Cab Trucks will have a BCM with only front mounted Plugs.

 

Crew Cabs and SUVs will have both front plugs and top plug.

 

If you use a BCM From and SUV in a crew cab you will get rear access open on the DIC.

 

A good shop should only charge a couple bucks for a BCM Reprogram. Takes about 2 mins to flash and another couple to set up the radio and sdm if required.

[Gmman]

Can this be done on a 2017 Silverado?

[silveradosid]

yes but a 2017, you need to have a mdi, gm's gds and buy a subscription for sps

[joyce reynolds]

Hello,my ignition switch on my 07 tahoe need a replacement  my question is  I call  a part store  and  they told me I will have to take the truck to a dealership to get it  program, even if I bought  the switch. 

[Hector Reyes]

Hi I replaced my old bcm to my 2003 saturn vue a day go and it looks like there's no communication between  the key and my bcm?