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Isolating Modules From the Data Bus for Programming
Posted to Technical Tips Forum on 8/25/2013 40 Replies

Some of you probably know this trick so for you this is review. I recently read a Tech Help request from a tech that was having difficulty programming a BCM in a 2000 Saturn. Typically a module will fail to program and you will get an error message and the dreaded "PROGRAMMING FAILED" message on you computer screen. In some cases aftermarket equipment installed in the vehicle such as a non OE radio is the culprit. A call to the help desk will often instruct you to disconnect any aftermarket equipment. A radio usually isn't a big deal but what do you do when you can't easily confirm the installation of some aftermarket device or it's impractical to disconnect every piece of AM gear in a vehicle? Such was the case on a 2007 GMC Sierra 3500 I was called out to program. This vehicle is a catering truck with all manner of things installed after it left the factory. I was called to program a Trans Control Module as this truck had a reman trans installed. On this truck both Engine and Trans are programmed at the same time. I got error messages each time I attempted to program. My solution was to isolate the Engine and Transmission modules so that they were the only two modules on the CAN bus. Using a diagram of the CAN bus wiring I found that unplugging the BCM connector containing the CAN bus lines would remove the rest of the modules. All that was left was to connect the bus lines to the ALDL using a pair of jumper wires. Programming successful! This can also be done on serial data systems and in most cases is easier as there is usually a serial bus splice connector that can be accesses and jumpered.

2007 GMC Sierra 1500 Classic SL, ECM/Inputs/Outputs Photo

Reid from New Jersey

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