2004 Toyota MR2 C56FACTORY OEM SERVICE PROCEDURE

Inspection Procedure

HINT:

  • If DTCs P0860 and P1646 are output simultaneously, the fail-safe function stops the engine. It the engine is stopped, the transmission control system may be abnormal (See PRE-CHECK ).
  • Read freeze frame data using the hand-held tester or the OBD II scan tool, as freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, this is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.
  1. Are there DTC P1646 and DTC for SMT being output? 
    1. YES : Go to transmission control system (See  PRE-CHECK  ). 
    2. NO : Go To Next Step 
  2. Check transmission control ECU (See  DIAGNOSTIC TROUBLE CODE CHART  ). 
    1. NG : Replace transmission control ECU. 
    2. OK : Go To Next Step 
  3. Check harness and connector between transmission control ECU and ECM (See  PROCEDURE  ). 
    1. NG : Repair or replace harness and connector. 
    2. OK : Replace ECM (See  ENGINE CONTROL MODULE (ECM)  ). 
Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.