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1998 TOYOTA TACOMA
2.7L I4•RWD•AUTOMATIC•gas
5 active safety recalls on this vehicle — view recalls
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Repairs0Labor1042Torque1610Fluid17DTC3334Battery2Maintenance0Recalls5
P0859moderate severityPowertrain

TCM Communication Circuit Low

on 1998 Toyota Tacoma 2.7L I4 · RWD

What this code means

The TCM communication circuit voltage is lower than expected. This may prevent proper data transfer between control modules.

Symptoms

  • Transmission fault indicator
  • Loss of shift control
  • Stored communication codes

Common causes

  • Short to ground in circuit
  • Corroded connectors
  • Faulty TCM
  • Wiring harness damage

Diagnostic steps

  1. Retrieve stored trouble codes
  2. Inspect circuit for short to ground
  3. Measure circuit voltage
  4. Verify TCM operation
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