Hi, Thanks for allowing me to join. I have been struggling with my truck for about 4 weeks. Any help would be appreciated.
2004 Silverado 2500 (not HD) crew cad 4x4 with 6.0 gas burner.
I was driving down my driveway and it shut off. It will spin over for a couple of seconds then stop each time I turn the key. I have 60lbs of fuel pressure, no fire to any coils, no pulse to the injectors. no power or signal to the crank sensor. I had it scanned and it shows BCM and ECM good but can't connect to the anti-theft module. The security light comes on for bulb check and then turns off. I list below what I have already done.

checked each fuse for power, ohm them out and pulled to do visual inspection. Also moved fuses to different spots.
replaced crank sensor, replaced cam sensor (before I knew that they were not getting a signal)
replaced ignition cylinder and re-pinned it, replaced ignition module, 30 min relearn was tried after each replacement.
all grounds have been checked and confirmed.
I did the (cut and connect yellow to black wire) in the 3 wires coming from the top of the switch and did the relearn.
After all of this nothing has changed. My next move is to replace the ECM and BCM.

I have many friends that are full-time mechanics and this has them scratching their heads. Have any of you experienced this?
Thanks again,
Marty

 

Anti-theft is a function of the BCM - there’s no separate module.

If the anti theft system is responsible for the no start there will be a related code stored in the PCM or BCM.

Some trucks had problems with the wiring harness under the driver seat chafing and causing a no start, so maybe inspect it and repair if needed.

The BCM’s in these era trucks get more sensitive to humidity as they get older. If the anti-theft is activating even if it shouldn’t be, disconnect the negative battery cable, remove the BCM from the truck and put it in an air conditioned house or room for a couple of days to dry it out. It may help to open the case and run a small fan on it.

If the truck starts after that, you can either get a replacement which will require dealer programming or you can send in the one you have for repair.

 

Thank you for the tips, When the guy read it with the scanner it scanned the ECM and said good, It scanned the BCM and said good then It came up and showed unable to communicate with anti-theft. No codes in BCM or PCM. I will check under the drivers seat. I do not have any moister in the vehicle. I had a leaking windshield on the BCM side 6 months ago. But I pulled all carpet and replaced backing and carpet after having the windshield replaced. It has been dry since. I did have a brake booster hose leaking and when I checked my ECM it had power steering fluid all in the pins and connections. I was able to clean it good with electrical contact cleaner.

 

What kind of scanner was used? It may not be capable of recognizing the anti-theft system isn’t a standalone module.

As for moisture - there doesn’t have to be water intrusion into the cabin for the BCM to be affected - depending on the module condition, the humidity in the air is enough to cause issues.

 

Not really sure of the model, but it came off the Snap On truck. I think it was the Edge. My truck has 300K plus miles and I was going down my gravel driveway so it is a little bumpy when it died. He has used the scanner in his shop for a while. I would think that he has seen it communicate or at least has not seen it read (unable to communicate with anti-theft) from his reaction. I'm going to check the wires under the seat tomorrow if the rain holds off. If that's not it would you recommend changing the BCM or ECM first?

 

I’d recommend diagnosing the problem before changing out any parts, especially modules.

The rule for diagnosing modules is to check the inputs and the outputs. In other words, check for signals you know you should have. If you find a relevant signal is missing the next step is to verify all the battery and ignition switch power feeds are there, then verify all the grounds are good.

If all the power and ground feeds are good but a signal is missing, consider the module faulty.

You’re going to need either a wiring diagram or connector pin out for the BCM. There are several power inputs - at least 1/2 dozen - but I don’t know them all off hand.

 

Hi there. I'm having same problem. Did you ever find a solution.