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2015 KIA FORTE
1.8L I4•FWD•AUTOMATIC•gas•G4NB
1 active safety recall on this vehicle — view recalls🏆Sponsored by Simon-Olivier Ricci
Repairs401Labor487Torque3387Fluid7DTC1835Battery1Maintenance0Recalls1
P1602high severityPowertrain

TCM Serial Communication Problem

on 2015 Kia Forte 1.8L I4 · FWD

What this code means

The PCM has detected a serial communication problem with the Transmission Control Module. Data exchange between the PCM and TCM is interrupted or corrupted, preventing coordinated powertrain operation.

Symptoms

  • Check Engine Light
  • Transmission in limp mode
  • Harsh shifting
  • No upshifts or downshifts
  • Cruise control inoperative

Common causes

  • Faulty TCM
  • CAN bus wiring damage
  • Corroded CAN bus connector
  • TCM power or ground issue
  • PCM CAN bus driver failure

Diagnostic steps

  1. Check TCM power supply and ground connections
  2. Inspect CAN bus wiring between PCM and TCM
  3. Test CAN bus resistance (approximately 60 ohms between CAN-H and CAN-L)
  4. Attempt to communicate with TCM using scan tool
  5. Check for TCM-specific DTCs

Repair notes

Repair CAN bus wiring or connectors; replace the TCM if it has failed internally.

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