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1993-1997 VOLVO 850

2.3L I5 Turbo•FWD•AUTOMATIC•gas•turbo
6 active safety recalls on this vehicle — view recalls
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Repairs0Labor565Torque2410Fluid6DTC626Battery1Maintenance0Recalls6
P1618high severityPowertrain

TCM-ECM Communication Fault

on 1993-1997 Volvo 850 2.3L I5 Turbo · FWD

What this code means

The ECM detected a communication fault with the Transmission Control Module (TCM). The CAN bus communication between the engine and transmission controllers is disrupted or unreliable.

Symptoms

  • Check Engine Light
  • Transmission may enter limp mode
  • Harsh or incorrect shifting
  • Transmission warning light
  • Reduced power

Common causes

  • CAN bus wiring fault between ECM and TCM
  • TCM failure
  • ECM CAN driver failure
  • Corroded CAN connector
  • CAN bus termination resistor fault

Diagnostic steps

  1. Check CAN bus communication with diagnostic tool
  2. Test CAN High and CAN Low signals
  3. Inspect CAN bus wiring between ECM and TCM
  4. Test CAN termination resistance
  5. Check TCM power and ground

Repair notes

Repair CAN bus wiring or replace the faulty module (ECM or TCM).

Other Powertrain codes on this vehicle

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