be used to bleed the ABS brake system without introducing air into the system. The extent to which it can be used to tune a C5 is that if you have a PCM Image that will work for your car you can save the current PCM Image and flash the new one you have onto the PCM. It cannot go in and individually change the tuning tables in the PCM as can say either EFI Live or HP Tuners tuning tools. But then those tools cannot touch the BCM either.
If you do or plan to do a lot of diagnostic work on your car it can be a worthwhile tool. Most of the diagnostic charts in the factory service manual assume the availability of a Tech 2 Scan Tool. But you have to learn to use the tool like any other computerized diagnostic tool. It has layers and layers of menues to wade through. But in certain diagnostic situations it can be an invaluable tool because it allows you to turn on and off hundreds of computerized settings to aid in the diagnosis process.
GM intentionally dumbed down the capabilities of the Tech 2 to change things to avoid law suits due to an errant technician that changed engine or emissions settings that could result in engine damage or emissions violations.
I like that the ever-knowledgeable 8VETTE7 pointed out the differences between accessibility between the BCM and the PCM because there’s often a lot of confusion between them, especially when quick questions arise in the FB groups or similar about tuning. For the very basics just look at the “B”CM as controlling the “body” and the “P”CM as controlling “power” (or engine power, rather).
There are also some things that the Professional Diagnostic Tool Tech2 cannot do despite it’s accessibility. An example would be the EBCM errors that are spoken of with frequency; you cannot simply use a Tech2 to program the errors out or “remove” them. If it were that simple we wouldn’t have all the threads about EBCMs.