P1765 – Transmission Control Relay (Toyota)

Description

The ECM detected a malfunction in the transmission control relay affecting power delivery to the TCM.

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Symptoms

  • Failsafe mode
  • Harsh shifting
  • Delayed shifting
  • No communication
  • Check engine light

Causes

  • Faulty relay
  • Corroded contacts
  • Wiring issues
  • Connector failure
  • Voltage instability

Diagnosis

  • Test relay operation
  • Inspect wiring
  • Check connectors
  • Measure voltage
  • Scan TCM data

Repair

  • Replace relay
  • Repair wiring
  • Clean connectors
  • Stabilize voltage

Related Problems

Related Fault Codes