of the automakers sell their own PassThru tool, but many recommend products that they have validated internally.
The SAE is planning to publish a conformance test. The conformance test has been named J2534-3, and will be applied to J2534-1 devices. The numbering is confusing, but remember that J2534-1 is the standard for reprogramming, and J2534-3 tests for conformance to J2534-1. There is even a J2534-2 published spec, but that doesn’t apply to EPA reprogramming requirements. Once the J2534-3 test has been published, a tool manufacturer should be able to certify that their products pass the J2534-3 test. The J2534-3 conformance test has not been published yet, so for now you should look for devices that have been validated by the automakers. Many of the automaker websites in Figure 1 have a list of recommended devices. Of all vendors offering J2534 tools, at the writing of this article, Drew Technologies has been validated by more automakers than any other.
ROI The initial purchase price for getting acquainted with J2534 will pay back over time and generate revenue. Although each price is different, the average software charge from each automaker is approximately $25 per flash over time. The average revenue for shop service tickets that include a reflash is $150. At four tickets per month, the shop would pay $100 in software fees and make back $600 in gross revenue. That equals $6000 per year in revenue. You will spend around $2000 on J2534 equipment up-front. If you use the tools you purchase and offer these services, the cost will pay itself back in a very short time.
Onboard VS Offboard Onboard programming means that you are reprogramming the vehicle’s computer while it is installed in the vehicle and offboard reprogramming means you are removing the computer from the vehicle and reprogramming it from a bench top with a special cable and power supply. Figure 4 shows what an offboard reprogramming bench may look like. There are some pre-made offboard cables available for certain vehicles, but there are literally dozens of different types of onboard computers, connectors, and pin diagrams.
Unless you have a specific reason to remove the onboard computer from the vehicle and reprogram it from an offboard bench, or unless you have advanced experience with J2534, you should leave the onboard computer installed in the vehicle when reprogramming. Many of the J2534-1 applications may try to reprogram more than one module when you select a reprogramming operation, and the only way you can guarantee all necessary modules are reprogrammed and the software matches is by reprogramming the computer while it is installed in the car. This is the way the automakers intend you to use their software, and for that reason onboard programming is preferred. There are some special cases where offboard reprogramming becomes more advantageous, but you must first have knowledge of that specific processor and configuration to understand the possible risks of reprogramming a module outside its normal environment.
Drew Technologies, Copyright 2009