TCM Transmission Control
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      1. UpFix FAQ's
      2. Automotive
      3. TCM Transmission Control

      I still have a P0742 code on my Mazda after a TCM rebuilt and hard shifts with the Check Engine & AT Light on.

      If the TCM was already refurbished and you're still getting the DTC (diagnostic trouble code) P0742 there can be a few reasons for that:
       
      • Low transmission fluid level
      • Dirty transmission fluid
      • Faulty torque converter clutch solenoid valve
      • Torque converter clutch solenoid valve harness or connectors
      • Torque converter clutch solenoid valve circuit is open or shorted
      • Transmission internal mechanical problem
       
      The first step is to perform a hard reset (link here). After that make sure the transmission fluid is not dark. It should be a bright red color. If it's dark, chances are that the transmission filter is also dirty and the TCM will detect an issue and throw a code.