P1600 TOYOTA - ECM BATT Malfunction

Battery positive voltage is supplied to terminal BATT of the Engine Control Module (ECM) even when the ignition switch is OFF for use by the Diagnostic Trouble Code (DTC) memory and air–fuel ratio adaptive control value memory, etc.

P1600 TOYOTA - ECM BATT Malfunction

P1600 TOYOTA Possible Causes 

  1. Open in back up power source circuit 
  2. Faulty Engine Control Module (ECM) 
  3. Engine Control Module (ECM) harness is open or shorted 
  4. Engine Control Module (ECM) circuit poor electrical connection



HINT: Read freeze frame data using TOYOTA hand–held tester or OBD II scan tool. Because freeze frame records the engine conditions when the malfunction is detected, when troubleshooting it is useful for determining whether the vehicle was running or stopped, the engine warmed up or not, the air–fuel ratio lean or rich, etc. at the time of the malfunction.