Windows PC Generic Programming

Motor, Sep 2004

Asking independent shops to buy subscriptions to factory-specific programming systems (often requiring a factory scan tool) was an interim approach to giving the aftermarket access to the capability. But it was obviously unrealistic to expect the typical shop to buy a stack of factory scan tools. So the EPA led a move to "generic programming" a single device for all makes-which is covered by SAE document J2534.

The idea is this: You download an operating program to your Windows PC-a separate program for each vehicle maker. That's as specific as it gets. The generic device is called a "Pass-Thru"; it's an electronic black box that passes the new program through to the vehicle via the underdash diagnostic plug-same as with the factory programming systems now in use.

That one Pass-Thru works with all makes, so you don't have to buy a lot of tools. It even works with on-board computers other than the PCM. In a typical scenario, the specific program checks the software level in the car computer and compares it with what's available at the factory website. If there's something newer on the website, the technician can download and install it through the PassThru and generic cables. On a few cars, particularly older BMWs, a special cable also may be necessary. J2534 programming requires high-speed Internet access; dial-up isn't an option, even if you don't mind being patient.

With other on-board computers, you might have to check the calibration and compare it with an on-website chart of the latest numbers to determine if there's an upgrade to install.

When It Starts

Programming is available now at some websites (Ford, Mazda, Chrysler and BMW), with charges starting at $25 a day. There have been technical issues identified in the J2534 document, which is going through a final revision, at which time it should enable the Japanese companies to offer it. General Motors people, who have been heavily involved in the development of the SAE document, also should offer their website version at the same time. Likely availability for that is sometime next year. The EPA regulation specifies that all 2004 programmable computers meet J2534, and all makers have agreed to make it available as far back as possible, in most cases to the start of OBD Il with 1996 vehicles. So except for perhaps a handful of special cases, you will be able to do generic reprogramming.

However, there are few Pass-Thrus available at this time. They're not inexpensive ($900 to $1600) because they're being made in low volume by companies who specialize in development engineering. It seems likely we'll see Pass-Thru devices that meet most of the J2534 specifications at very low prices, perhaps just an upgrade of some sort to your aftermarket scan tool. Some of the carmakers use "programming voltages"-very high voltages (up to 20 volts) that are part of the process. So if a tool manufacturer has to provide a voltage generator, that adds to complexity and cost. Furthermore, Chrysler Group products require that a Pass-Thru recognize SCI (Standard Corporate Interface), a non-OBD Il computer protocol, and that also adds to cost. In addition, some tool manufacturers are looking at wireless Pass-Thrus as high-end offerings. In any case, you'll see a wide selection and you'll be able to pick something that meets your needs. If you intend to program only one or two vehicle makes, you might be more happy with a basic Pass-Thru than a shop looking to cover all.

If you want to get a website explanation of J2534 programming, go to Ford's www.motorcraftservice.com and click on Programming Modules. The explanation is exactly the same as at the Mazda website. For Chrysler, click on the FLASH button at the top of the page following login. For BMW, click on Additional System Requirements, near the bottom of the home page.