If you own a Jaguar XJ220 or the rarer XJR-15, you’re probably not short on money or real estate. You may, however, be finding it hard to lay your hands on a diagnostic tool that is compatible with the ancient Zytek ECU. Thankfully, [Tom Radom], is working to change that.
As the owner of XJ220 chassis #50, [Tom] was unlucky enough to see the dreaded check engine light come on last year. He was lucky enough to get his hands on an SPD-1039 interface, built to talk to the Zytek ECU that runs the car. However, he was painfully aware that these devices are now incredibly rare and hard to come by, even given the tiny limited market of owners of 1990s Jaguar supercars. Thus, he set about building a replacement.
An initial effort to open up and reverse engineer the Zytek interface failed, mostly because it had been potted rather successfully in silicone. Thus, [Tom] took a new tack. He hooked up a logic analyser between the interface and the car, recording the traffic between the two. This captured data allowed [Tom] to recreate the interface using a FT232RNL bridge to chat to the Zytek engine control unit. There was no attempt to rebuild the software—the original DOS-based diagnostic still runs perfectly fine in an emulator. It was just the hardware interface from a serial port to the car that needed to be recreated.
[Tom] has been building the modules and supplying them to owners of XJ220, XJ220S, and XJR-15 models at no charge. He believes simply having a viable diagnostic tool available will increase the value of these classic cars by more than the costs he incurred to develop the interface. Interested parties can submit their details via webform on Port220.com.
For a modern vehicle, the ECU is everything. Without it, the car doesn’t run. That’s why we’ve seen some heroic fixes to rescue cars and get them back on the road. If you’re doing your own wizardry to talk to cars of the past, don’t hesitate to notify the tipsline.