A common issue with the Mitsubishi Outlander equipped with the TC-SST transmission is the dreaded P1590 error code. This code signifies a communication problem between the Transmission Control Unit (TCU) and the Engine Control Module (ECM), specifically concerning torque reduction requests. This article will discuss a personal experience with this error, including diagnosis and solution, aiming to assist other Outlander owners facing similar challenges.
Understanding the P1590 Error Code
The P1590 error, formally described as “TC-SST-ECU to ECM Communication Error in Torque Reduction Request,” indicates a breakdown in communication between the transmission and engine control units. This disruption can lead to various drivability problems, including the transmission entering a fail-safe or “limp” mode. In my case, after accidentally shifting into neutral at around 45 mph and then back into drive, the engine revved high, a “transmission overheating” warning flashed briefly, and then no gears would engage. The car wouldn’t move, even after restarting and attempting different driving modes.
Along with the P1590, a U0101 code, indicating a “TCM Time-out,” may also appear. This further points towards a communication issue with the transmission control module. Initial troubleshooting involved checking connections, fuses, relays, and transmission fluid levels, all of which were normal.
Diagnosing and Resolving the Issue
Using an OBD-II scanner and EvoScan software, the P1590 and U0101 codes were retrieved. Researching these codes led to Mitsubishi’s technical information, confirming the communication error diagnosis and suggesting the possibility of the transmission being in limp mode. This situation often necessitates a “re-teach” procedure for the TC-SST, essentially resetting the transmission’s learned parameters.
While initially daunting due to the perceived complexity of the re-teach process, a recently published YouTube video provided a detailed walkthrough. The video outlined the necessary software, file downloads, conversion steps, and the re-teach procedure itself, making the process significantly more manageable. Following the instructions in the video meticulously, the re-teach procedure was successfully performed.
Successful Outcome and Recommendations
Following the TC-SST re-teach procedure, the issue was completely resolved. The transmission resumed normal operation, and shifting felt crisp and responsive. This experience highlights the importance of accurate diagnostic tools, access to reliable technical information, and the value of shared knowledge within the automotive community.
If you encounter a P1590 error code on your Mitsubishi Outlander, it is crucial to:
- Retrieve diagnostic trouble codes: Use an OBD-II scanner to identify all error codes.
- Consult reputable resources: Refer to Mitsubishi’s technical information or reliable online forums.
- Consider a TC-SST re-teach: If other troubleshooting steps fail, a re-teach procedure may be necessary. Seek guidance from experienced technicians or detailed tutorials.
This personal experience demonstrates that a seemingly complex issue like a P1590 error can be successfully diagnosed and resolved with the right information and guidance. Hopefully, this information proves beneficial to other Mitsubishi Outlander owners facing similar transmission problems.
