The evolution of GM Tech 2, MDI

I have written several guides on scan tools and programming. I apologize in advance for the typos or mis-spellings. The spell check on okay really blows and they do not allow for cut and paste from Word. Im not an English teacher, I am a vehicle tech, so if you can look past the typos, there is some good information in here!
I have been asked to provide my background on the GM family of vehicles. Unfortunately for those of us who are in the high end diagnostics and flash programming game, the game is about to change for those of us who work on GM products. The way we do business and diagnose cars in the GM family has made the Tech 2 a dinosaur.
Before we begin, let me say that I will not be spending anytime on Tech 1 because, quite frankly, Tech 2 is still the flagship unit to this date and is backwards gepatable with OBD I. For you folks who want to stick with just OBD 1 applications and some very limited OBD 2 applications, you can get a Tech 1 on okay, but frankly, if your buying a well geplimented unit for more than 50 bucks, you had better be a BIG fan of that scan tool! I see people practically giving them away on Craig$ list.
Tech 2 has been around since the 80's. Its the quintessential hand held stand alone unit that, it its day, was well ahead of its time design and technology wise. It was extremely useful in the dealership environment, but back in the 80's, dreadfully under utilized. Its simple menu's and functionality made this unit the standard for everyone else. Problem was that as much as they tried, Chrysler and Ford simply didnt get it back than, based on the loads of diagnostic tools, cables, and junk those guys kept putting out. The Menu did not change from vehicle to vehicle, the functions were pretty much all in the same place for all car lines and the number of cables and crap that one needed to have to respond to different GM cars was minimal.
Tech 2 gives its user an unprecedented amount of information you simply cannot get from a generic scan tool. It provides its user a ton of PID information from any module on any GM family vehicle. You simply cannot get more information out of a GM product than with a Tech 2. In addition to the vast amount of information you can get out of a PCM or any other module on any GM car or truck, you get the ability to do service bay and bi-directional testing. This means that you can control solenoids, motors, actuators, gauges, lights, and a lot of other stuff right through the scan tool. This allows for the technician to be able to actuate many of these things to verify thier operation and support geponentry. With service bay tests one can perform fuel injector balance tests, ABS HCU service bleeds, EVAP testing and many more important functions. Finally, if you want to flash program any module on a GM, a Tech 2 will give you several methods.

Stand alone - here you simply turn on your Tech 2, request vin information through the SPS function on the menu, than unhook your scanner from the vehicle, take it to your PC, and either log onto TIS on WEB to download flash programming, or you can hook onto your PC, and download the flash programming from your TIS program that you load onto your PC. Than you simply unhook the scan tool and take it back to the car, hook it back up to the ALDL and dump the programming onto the module you wish to program.
Pass thru - her you can hook your geputer to your Tech 2 using a serial port to CAT5 cable (generic adaptors wont work, it has to be configured specifically for GM diagnostics, data recorders, or TPMS units) than hook your Tech 2 to the the vehicle ALDL connector, open the TIS program, and flash directly from your PC to your module. Now you USED to be able to do this wtih TIS to WEB but it looks like they have disabled the function that allows pass thru programing via TIS to WEB directly to the controller through the Tech 2. Why they did this has begee a little bit of a debate among my associates and myself. Many think its because GM has begun the changeover to the newer diagnostic and re-flash platform that no one (not even most dealerships) seems to have. Some think its because too many controllers are being wiped out by service interuptions via the internet. If a controller is being flashed and it is inturrupted in any way, it, for all intent and purpose, begees junk unless you have access to dealership reset codes called VCI numbers. Good luck getting one of those outside the dealership! Hell, good luck getting one INSIDE a GM dealership!
Some Tech 2 PCM programing tips:
PCM's
Now even with the differant modes of programing some modules, there are some variations on doing functions like programing Body Control Modules (BCM's)and doing security re-learns. Although many modules on a car are programable, and RE-programable, many Body Modules in OBD 2 GM cars are not programablelike engine controllers are.
Engine controllers, dashboard controllers, ABS controllers and several others can be programmed and re-programmed. Many people have said to me over the years, including dealership tech's that GM PCM's cannot be re-programmed once they have a VIN number inside them. Nothing could be farther from the truth! Of course, I am sure they would love to have you believe that because they sell controllers. 90% of all GM PCM's simply need to be treated as though they were brand new when being installed from another car. The only real differance is that when the vin number varification box pops up, it will have the VIN number from the old module in there. When the program display's that, along with the prompt "is this the correct VIN number?" Simply hit the NO response and type in the VIN number you want. This will push the new VIN into the controller. Keep in mind that once you install a used controller in a car and hook up the battery, the security system will see another VIN number and throw the vehicle into theft lock. This is easily fixed wtih a simple security re-learn if you have a Tech 2 and a copy of TIS. Many generic pass thru units will also have the abiltiy to do a security re-learn as well.
BCM's
On most GM Body Controle Modules, you have to manually enter a VIN number with the Tech 2 Keypad, than select the optional and standard equipment that you want to operate. For instance, if you have an Impala with optional driving lights, you will have to activate that function when programing and setting up a new BCM. The bad news is that, unlike many factory PCM's most factory equipped BCM's are locked up and cannot be given a new VIN number making used GM BCM's worthless. Once you do get a new one, you can establish settings, and even a point of sale to record for future refrence within the BCM with the Tech 2.
There are some items out here on okay that allow for the erasure of a used BCM or any other module for that matter. They are generic geputer cards that, for the most part, are designed to erase pretty much any module out there. If you have any background or knowledge on erasing these types of modules like GM BCM's or Ford Air bag modules, I would sure love to hear from you! As you will read in some of my other postings, I LOVE to trade resources to fellow technicians and I have A LOT of great resources for programing on a lot of vheicles.
SECURITY RE-LEARN
As for security re-learns, many GM vehicles do not even require a tech 2 to re-program a pass key modlue. There is a procedure where you manipulate the key to the KOEO postion and turn it off a few times and you can re-learn a pass key system. With Tech 2 the procedure is a little easier and faster as you can simply hook up your Tech 2, link it to TIS and do a relearn in about 10 minutes through SPS. There are some GM vehicles that MUST be done with the KOEO process as the security re-learn function just does not exist in Tech 2 programming.
***A note for you guys using Pass thru units for security re-learns: Most generic pass thru units WILL NOT do security re-learns even with TIS on Disc or TIS on WEB. Particularly, single wire CAN vehicles and a few OBD II's simply wont work with geneirc pass thru units. Consider that the federal government only requires access to PCM, and TCM units to the general public. Anyting else is just a bonus. This is why a Tech 2 is so much better than a pass thru. You cant program most BCM's on GM with a generic pass thru nor can you do a lot of security re-learns.
Tech 2 Memory Cards
Memory card issues are also a consideration for Tech 2 units. The standard is a 32 Megabite PCMCIA style card that slides into one of the two slots on the top of the Tech 2 head unit. This card holds all your diagnostic information and updates, and also has room for flashes you will need to transfer to the vehicle your working on. Earlier units had 10 megabite cards, but there is almost NO GM program updates that will fit on such a small memory. Even legacy programs for Saab, Suzuki, Toyota, and Isuzu require at least a 32 megabite card. Very few applications will fit on a 10 Mb card. Lots of folks, however, use a 10Mb card in the second slot for data logging and storage of freeze framd data so dont throw your 10Mb card out just yet.
TIS on DISC