Caution / Notice / Hint

HINT:

In contrast to normal malfunction diagnosis for components, circuits and systems, DTC P1604 is used to determine the malfunctioning area from the problem symptoms and freeze frame data when the user mentions problems such as starting difficulty.
As the DTC can be stored as a result of certain user actions, even if the DTC is output, if the customer makes no mention of problems, clear the DTC without performing any troubleshooting and return the vehicle to the customer.
If any other DTCs are output, perform troubleshooting for those DTCs first.
When the Data List item "Immobiliser Fuel Cut" is ON, the engine cannot be started.
Read freeze frame data using the Techstream. Freeze frame data records engine conditions when a malfunction occurs. This information can be useful when troubleshooting.
When confirming the freeze frame data, be sure to check all 5 sets of freeze frame data.
Refer to FREEZE FRAME DATA [12/2012 - ]
When confirming the freeze frame data, if there are multiple items related to the cause of the malfunction, perform troubleshooting for all related items.
Try to start the vehicle under the conditions recorded in the freeze frame data which were present when the malfunction occurred. Confirm the data at this time and compare it with the freeze frame data.
If the malfunction does not reoccur, carefully check the vehicle conditions from when the malfunction occurred using freeze frame data.
When performing inspections, jiggle the relevant wire harnesses and connectors in an attempt to reproduce malfunctions that do not always occur.
If the same inspection or replacement procedure appears 2 times when performing a procedure, it is not necessary to repeat the procedure the second time.

Malfunction Recurrence and Inspection Areas
1. Freeze frame data exists, but the malfunction (starting difficulty) has not reoccurred and the malfunction conditions are unknown.
  1. The engine speed recorded in the freeze frame data is 0 rpm (the engine does not crank).
    HINT:
    
    One of the following problems may be present: battery depletion, excess engine friction, a starter malfunction or a crankshaft position sensor malfunction.
    - If the battery voltage is less than 6 V during cranking, there is a high probability that engine friction is abnormal.
    - If the battery voltage drops to 5 V or less when starting the engine, the battery may be malfunctioning.
    - If the battery voltage fluctuates while cranking the engine, it can be concluded that cranking is being performed. When the engine speed is 0 rpm, the crankshaft position sensor and/or an ECM may be malfunctioning.
      
      Fig 1: Starting Difficulty Inspection Flow Chart (Engine Speed 0 RPM)
      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  2. All engine speeds recorded in the freeze frame data are between 60 and 250 rpm (the engine cranks but there is no combustion).
    HINT:
    
    If the engine speed is between 60 and 250 rpm (no initial combustion), there may be a wiring problem or a complete failure of an ignition or fuel system part.
    - Due to an engine coolant temperature sensor malfunction, the fuel injection volume is extremely high or low and the engine may not be able to be started.
      
      Fig 2: Starting Difficulty Inspection Flow Chart (Engine Speed Between 60 & 250 RPM)
      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  3. The engine speed recorded in the freeze frame data is 250 rpm or higher (the initial combustion and starter turnoff timing is too late).
    HINT:
    
    If the engine speed is 250 rpm or higher (combustion occurs but the initial combustion and starter turnoff timing is too late), the fuel injection volume is often incorrect (too low or too high) and determining the cause of the malfunction is often difficult.
    - Due to an engine coolant temperature sensor malfunction, the fuel injection volume is extremely high or low and engine starting trouble may occur.
    - If Long FT #1 is incorrect, there may be a fuel supply problem due to the injectors or fuel pump being clogged, etc.
    - If the engine cranking speed is too high, compression loss may have occurred due to carbon interfering with the valve operation.
      
      Fig 3: Starting Difficulty Inspection Flow Chart (Engine Speed 250 RPM Or Higher)
      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. When the malfunction (starting difficulty) can be reproduced, or malfunction conditions are known, perform the following inspections ("Problem symptoms" and "Systems to inspect")
  1. Problem symptoms
    1. The engine does not crank.
      HINT:
      
      The starter is normal if a noise that indicates the starter pinion gear is extending is heard. The battery may be fully depleted or there may be excess engine friction.
    2. The engine cranking speed is abnormal.
      HINT:
      
      If the engine cranking speed is too high (for example, 300 rpm or higher with no combustion), compression loss may have occurred because carbon interfered with valve operation, etc.
    3. There is no initial combustion.
      HINT:
      
      If there is no initial combustion, there is probably a wiring problem or an ignition or fuel system part malfunction.
    4. The engine stalls after starter turn off.
      HINT:
      
      If the engine stalls after starter turn off, the air fuel ratio may be incorrect or the VVT may have a problem returning.
    5. The initial combustion and starter turn off occur late.
      HINT:
      
      If the initial combustion and starter turn off occur late, the fuel injection volume is probably incorrect (too low or too high).
      
      HINT:
      
      Causes of fuel system malfunctions according to conditions present at the time of the malfunction.
      - When 2 to 3 minutes have elapsed after stopping the engine: Fuel pressure loss due to the fuel pressure regulator failing to maintain the fuel pressure.
      - When 15 to 120 minutes have elapsed after stopping the engine: Problem with injector fuel seal.
      - When a long time has elapsed after stopping the engine: Fuel pressure regulator is stuck open.
  2. Systems to inspect.
    1. Intake system
    2. Ignition system
    3. Fuel system

INSPECTION FLOW

Freeze frame data exists, but the malfunction (starting difficulty) has not reoccurred and the malfunction conditions are unknown.

Freeze Frame Data Item	Result	Suspected Area	Procedure
Engine Speed	0 rpm (no engine cranking at all)	Battery fully depleted Engine assembly (excess friction) Starter assembly Immobiliser system Crankshaft position sensor ECM	4 to 9
	60 to 250 rpm (engine cranks but no initial combustion*1)	Fuel pump control system Ignition system Engine coolant temperature sensor Fuel injection system	10 to 14
	250 rpm or higher (combustion occurs but initial combustion and starter turn off*2 occur late)	Engine assembly (compression loss) Fuel injection system Fuel pump control system	15 to 23

HINT:

*1: First combustion after cranking begins.
*2: Condition when engine speed increases and starter can be turned off.

When the malfunction (starting difficulty) can be reproduced, or when malfunction conditions are known.

Problem symptoms

Problem Symptom	Suspected Area	Suspected Component	Procedure
The engine does not crank	Battery malfunction	Battery fully depleted	26 to 31
	Starting system	Starter assembly (includes pinion gear wear or tooth damage) Starting system
	Engine assembly	Engine assembly (excess friction) Drive plate and ring gear sub-assembly wear or tooth damage
Cranking speed too low	Battery malfunction	Battery fully depleted	32 to 34
	Starting system	Starter assembly
	Engine assembly	Engine assembly (excess friction)
Cranking speed too high	Engine assembly	Engine assembly (compression loss)
There is no initial combustion	Fuel supply problem	Cannot maintain pressure due to fuel pressure regulator malfunction Fuel injector assembly leak Fuel leak from fuel line Fuel pump control system Fuel pump	35 to 48
There is no initial combustion	Ignition system malfunction	Spark plug Crankshaft position sensor Ignition coil assembly	35 to 48
Engine stalls after starter turn off	Air suction	Intake system connections	67 to 71, 92
	Deposits in throttle body	Throttle with motor body assembly
	VVT valve does not return properly	Camshaft timing oil control valve assembly
	Mass air flow meter sub-assembly malfunction	Mass air flow meter sub-assembly
The initial combustion and starter turn off occur late	Engine coolant temperature sensor malfunction	Engine coolant temperature sensor	49 to 61, 73
	Mass air flow meter sub-assembly malfunction	Mass air flow meter sub-assembly
	Abnormal A/F learning value	Air fuel ratio sensor
	Deviation from fuel injection characteristics	Fuel injector assembly
	Wet-fouled or dry-fouled spark plug	Spark plug
	Lack of fuel pressure	Fuel pressure regulator Fuel pump Fuel pump control system

Systems to inspect.

Troubleshooting by System	Suspected Area	Suspected Component	Procedure
Fuel system troubleshooting A	Abnormal air fuel ratio learning value	Fuel injector assembly	86 to 91, 93, 94 95 to 102
	Rough idling	Crankshaft position sensor
	Abnormal fuel pressure	Fuel Fuel leak from fuel line Fuel pump Fuel pressure regulator
Fuel system troubleshooting B	Abnormal concentration of HC in surge tank	Purge VSV system Fuel injector assembly	103 to 105
Fuel system troubleshooting C	Injection signal system malfunction	Fuel injector assembly Crankshaft position sensor Camshaft position sensor ECM	63 to 66, 72
Intake system troubleshooting	Difference between ISC target value and opening angle when idling	Engine assembly (compression loss) Valve timing Engine coolant temperature sensor ECM	83 to 85 106 to 108
Ignition system troubleshooting	Camshaft and/or crankshaft position sensor signal malfunction	Crankshaft position sensor system (including sensor installation) Camshaft position sensor system (including sensor installation) ECM	74 to 82 109 to 117

NOTE:

Inspect the fuses for circuits related to this system before performing the following procedure.
After turning ignition switch off, waiting time may be required before disconnecting the cable from the negative (-) battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) battery terminal notices before proceeding with work.
Refer to PRECAUTION [12/2012 - ]