In parts I and II of this series of articles, we covered the basics of module programming and Ford Motor Company vehicles, respectively. In this installment, we will cover General Motors vehicles. Much like Ford, GM has allowed the aftermarket pretty extensive programming coverage. Almost all modules back to the 1996 model year, and a few select vehicles earlier than that, are included. Anti-theft, or vehicle theft deterrent (VTD) learning, is also included on most applications. For these reasons, GM is most likely the second vehicle line to add to your programming repertoire.
A General Motors Bonus
General Motors offers a free lookup tool (figure 1) that can be used for research before purchasing a programming subscription. Most manufacturers offer a tool to look up calibration numbers, but in my opinion, no one does it as well as GM. The website is currently: https://tis2web.service.gm.com/tis2web/.
Once the VIN number of a vehicle has been entered, the technician can view which modules are programmable on that exact vehicle entered and see if any modules have had updates issued since the vehicle was produced. The first statement, which modules are programmable, is very handy when writing a quote for a customer. For example, a module is diagnosed as a fault and needs to be replaced. While the service writer is compiling the estimate, the need to charge for a programming operation can be determined. Service information can provide this data, but this tool is a quick and easy check (figure 2). Second, it can be used just like a Technical Service Bulletin (TSB) search.
If there have been software updates issued, the newest calibration numbers from the site can be compared to a calibration number pulled from the vehicle using a scan tool. Figure three shows an initial calibration number of 16001261 from when it was manufactured. It also shows the most recent calibration number, which is 15848470. In this case, the vehicle came in with the complaint of the CD would not eject from the radio. Might a programming event resolve this issue? Regardless of the vehicle at hand, this tool can provide valuable information during the diagnosis and/or the estimating process.
Hardware
Before the introduction of Global Architecture A, which was introduced on some 2010 model year vehicles and phased-in on all models over the next few years, the Tech2 was the factory GM scan tool. It’s still capable of programming and scan tool functions on older vehicles. A suitable J-2534 device is also capable of programming older GM vehicles. With the introduction of Global A, the GDS2 scan tool was introduced. It represented GM’s shift to a J-2534 compliant programming and scan tool platform.
GM also eventually allowed Tech2 scan tool functions to be performed with a J-2534 device, which, for the most part, eliminated the need to purchase the older Tech2 hardware. As a result, almost all scan-tool and programming functions can be performed with a compatible J-2534 device and the appropriate subscriptions. In addition, just like Ford, there is an inexpensive “Mongoose” interface (figure 4) made by Drew Technologies that can be purchased specifically for GM vehicles.
The Subscriptions
GM offers a variety of subscription options that include Tech2Win (Tech2 scan tool functions on a PC), GDS2 (Global A scan tool functions), service information, and module programming (or TIS), all of which are compatible with a supported J-2534 interface. Most of these subscriptions are available in a variety of short-term and long-term pricing options. The exception would be the programming option. Unlike most OEs, GM offers its programming subscription by the VIN number of the vehicle.
What is included: programming of all modules on a specific vehicle for 24 months for $40. This pricing seems reasonable but poses at least two issues for a shop that is programming many modules. First, since there is no long-term all-inclusive subscription available, we have to remember to charge the additional amount to cover the fee as well as track VIN numbers/ subscriptions for 24 months to be sure we do not pay multiple times for a regular customer. Second, WE NEED TO MAKE SURE THE VIN NUMBER IS CORRECT before we pay for the subscription. What I mean by this is: If a used module has ever been installed, the software will pull the wrong VIN number, and programming will be incorrect for the vehicle in the bay. Make sure the correct VIN number is identified before paying.
Programming
Once you pay your subscription fee, and the drivers for whichever hardware you chose to purchase are installed on your PC, there is no application to download and install from GM. Logging into your Service Programming (SPS) account will run you through a series of windows as the software verifies your subscriptions, updates the database, etc. Eventually, you will come to the programming screen.
The actual programming event is not that different than the Ford examples from last month’s article. Follow the directions and enter the correct data. The screens themselves vary slightly by vehicle but usually progress as follows: make your connections, build the vehicle, verify the VIN, choose the module to program, choose the correct calibration (if necessary), special instructions, and then program. The software will guide you through each step. Of course, if you read part I of this series, you already have your battery maintainer connected, and you followed the pre-programming checklist!
Once the programming event has completed a “Success!” screen (figure 5) will be displayed, and any additional controller specific instructions, a crank angle relearn, or BPP sensor calibration, for example, should be indicated.
Some modules may require setup functions with a capable scan tool in addition to programming functions. One example of this could be a Body Control Module (BCM). BCMs vary by application and may require extra configurations such as odometer reading, country of origin, option configuration (figure 6), VTD relearns and/or SDM primary key transfer. When replacing a GM BCM, do not plug in the new BCM and cycle the key until you are ready to perform these functions. In some cases, if the ignition is cycled too many times, the BCM may lock and not allow these procedures to be completed.
There are a couple of additional GM notes that you should be aware of. First, if a programming event on a GM vehicle fails: DO NOT TURN OFF THE KEY! No matter what the software tells you to do, repeat the process a few times to see if the programming event finishes. The moment you shut off the key, the module has most likely become a paperweight. I’m not saying this is common, but keep that in mind when programming a GM vehicle.
Second, sometimes you will be instructed to remove fuses to disable modules on the network during programming. The reason is because other modules “talking” on the network can corrupt the programming process. This is common on some GM’s vehicles equipped with a J-1850 Class 2 network. Some Cadillacs, Corvettes, Tahoes, and more will require additional steps to ensure the programming event completes successfully. The programming software should alert you if there is an issue. Follow all of the instructions in-service information and whatever the programming software instructs you to do.
A common vehicle with the issues mentioned in the last paragraph is a Chevy Trailblazer and its re-badged counterparts. When programming a module, the technician is often asked to remove the ABS and the LGM fuse from under the left rear seat fuse box. Again, this step is meant to take some modules off-line. There is another way to guarantee no interference. In the case of the Trailblazer, the Class 2 network has a spice pack that can be disconnected and will subsequently isolate every module on the network. It is located under the left side of the dashboard. When the comb is removed and using a wiring diagram, a jumper wire (figure 7) is installed to connect the appropriate module to the DLC. This procedure eliminates every other module on the network. Now the only module that can communicate on the network is the one you chose to program, and the rest of the modules can not interfere with the programming process.
To summarize, the GM programming procedure does not vary that much from other manufacturers. The appropriate service information should be consulted and will alert the technician to any specific details that should be adhered to. And of course, make sure your battery maintainer is connected during the entire programming process!
