Tired of inflexible AW4 transmission control units?

This page is for you, then. This project has been a long long time coming, I began working on it in 2009 and spent significant time on it in 2011, dropped it again, then picked it up again in 2015, then dropped it again until this year. At this point I want to actually finish the project. The basic idea is to build a replacement drop-in PCB for the XJ 1997 and 1998-2001 AW4 TCU enclosures that contains hardware to interface with all of the factory wiring, including the factory CCD bus, such that any aftermarket shifter can be used and a user configurable shift map or even full custom shift algorithm can be loaded into the microcontrollers memory. I have a complete prototype board finished that needs only firmware at this point, but will probably redesign the prototype to allow use of more modern components and increase flexibility.

Feature list:

  • Drop-in installation of PCB into 1997 & 1998-01 TCU housings
  • zero-modification connection to factory wiring harness
  • complete emissions compliance & no Check Engine Lamp illumination due to P1694 and P1698
  • optional: report expected P07xx series codes for *actual* transmission related faults so a scan tool is still useful to repair personnel despite custom TCU
  • support factory TPS, NSS, brake lamp, ISS/OSS, solenoid driver inputs and outputs
  • support an auxiliary I/O connector (optional, user may decide how to use) containing the following inputs and outputs:
  • CAN bus interface - for user custom firmware to implement as desired
  • RADesign/Winters shifter inputs for Rail Shifter to override factory shifter gear selection
  • tiptronic shifter inputs for up/down "flappy paddle" shifter switches
  • extra digital inputs for shift map selectors, race vs street mode switch, etc
  • several digital outputs for upshift lamp, gear indicator display, or other purposes
  • bluetooth and/or wifi interface for web or mobile app configuration tool to input shift map, I/O configuration, firmware update, etc
  • resistive mux switch input to use factory cruise control buttons as up/downshift buttons
  • default firmware to include basic shift map + I/O config tools as well as firmware update utility, TCU to be shipped with a custom binary library and headers along with a reference manual to use in implementing a complete custom firmware image for advanced users. You want some kind of "special sauce" that I didn't think of? By all means, build what you want for software. Want to PWM your shifts for comfort in street mode but run them on/off in race mode and use an unallocated digital output to tell your boost controller to back off and pull ignition timing 50mS before a shift to avoid melting your transmission when you're on the bleeding edge of what it can handle? Yeah, you can do that if you want. The sky, available I/O, and remaining EEPROM space are the only limits to what you can do.