Power Source Mode does not Change: Description

If the certification ECU detects the key inside the vehicle when the shift lever position is P and the brake pedal is not depressed, each press of the engine switch changes the power source mode in the following order: off, on (ACC), on (IG), off. If one of the DTCs shown in the following illustration is detected, correct the DTCs according to the DTC chart. If the power source mode is still malfunctioning, one of the following may have occurred: 1) the MPX circuit has a malfunction, 2) the certification ECU has determined that the key is not inside the vehicle, 3) the engine switch has a malfunction, or 4) the power source control ECU has a malfunction.

Fig 1: Power Source Control ECU Circuit Diagram

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. CHECK FOR DTC 
   1. Delete the DTCs.

      HINT:

      After all DTCs are cleared, check if the trouble occurs again 5 seconds after the engine switch is turned on (IG).

   2. Check for DTCs again.

      OK: 

      No DTC is output. 

   NG : GO TO DTC CHART 

   OK : GO TO NEXT STEP. 

2. CHECK BASIC FUNCTION 
   1. When the key is inside the vehicle and the shift lever position is in P, check that depressing the brake pedal causes the engine switch indicator to illuminate green.

      Result 

      ENGINE SWITCH INDICATOR RESULT CHART
      
      

      Result	Proceed to
      Indicator illuminates green	A
      Engine switch indicator circuit is normal but indicator does not illuminate green	B
      Room oscillator recognizes key but indicator does not illuminate green	C

   B : GO TO ROOM OSCILLATOR DOES NOT RECOGNIZE KEY 

   C : GO TO ENGINE SWITCH INDICATOR CIRCUIT 

   A : REPLACE POWER SOURCE CONTROL ECU