DTC P1644-00: ECU Malfunction (Starter Circuit) [10/2022 - ]: Procedure

1. Read the DTCs.

   Powertrain > Stop and Start > Trouble Codes 

   Result

   Result	Proceed to
   Only P0615-11 and P1644-00 are output	A
   Only P060B-1C and P1644-00 are output	B
   Only P060B-49 and P1644-00 are output	C
   Only P060B-71 and P1644-00 are output	D
   P1644-00 is output	E

   HINT: 

   If DTCs P060B-1C, P060B-49, P060B-71 or P0615-11 and P1644-00 are output simultaneously, troubleshoot for DTC P060B-1C, P060B-49, P060B-71 or P0615-11 first.

Result: 

A 

GO TO DTC P0615-11. Refer to  DTC P0615-11: Starter Relay Circuit Short to Ground [10/2022 - ]  

Result: 

B 

GO TO DTC P060B-1C, P060B-49 OR P060B-71. Refer to  DTC P060B-1C: Analog to Digital Converter Circuit Voltage Out of Range; DTC P060B-49: Analog to Digital Converter Internal Electronic Failure; DTC P060B-71: Analog to Digital Converter Actuator Stuck [10/2022 - ]  

Result: 

C 

GO TO DTC P060B-1C, P060B-49 OR P060B-71. Refer to  DTC P060B-1C: Analog to Digital Converter Circuit Voltage Out of Range; DTC P060B-49: Analog to Digital Converter Internal Electronic Failure; DTC P060B-71: Analog to Digital Converter Actuator Stuck [10/2022 - ]  

Result: 

D 

GO TO DTC P060B-1C, P060B-49 OR P060B-71. Refer to  DTC P060B-1C: Analog to Digital Converter Circuit Voltage Out of Range; DTC P060B-49: Analog to Digital Converter Internal Electronic Failure; DTC P060B-71: Analog to Digital Converter Actuator Stuck [10/2022 - ]  

Result: 

E 

See step  2

Pre-procedure1

• Disconnect the engine stop and start ECU connector.
• Remove the ST NO. 1 relay from the No. 1 engine room relay block and No. 1 junction block assembly.
• Disconnect the certification ECU (smart key ECU assembly) connector.
• Disconnect the ECM connector.

• Measure the resistance according to the value(s) in the table below.

  Standard Resistance

  Tester Connection	Condition	Specified Condition	Result
  A25-21 (STA) - ST NO. 1 relay terminal 2	Always	Below 1 Ω	Ω
  A25-21 (STA) - Body ground	Always	10 kΩ or higher	kΩ
  ST NO. 1 relay terminal 2 - Body ground	Always	10 kΩ or higher	kΩ

  Result

  Proceed to
  OK
  NG

Post-procedure1

• None.

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  3

1. Inspect the ST NO. 1 relay.

   Refer to ON-VEHICLE INSPECTION [10/2022 - ]

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPLACE RELAY (ST NO. 1 RELAY) 

Result: 

OK 

See step  4

Pre-procedure1

• Remove the ST NO. 1 relay from the No. 1 engine room relay block and No. 1 junction block assembly.

• Measure the resistance according to the value(s) in the table below.

  Standard Resistance

  Tester Connection	Condition	Specified Condition	Result
  ST NO. 1 relay terminal 1 - Body ground	Always	Below 1 Ω	Ω

  Result

  Proceed to
  OK
  NG

Post-procedure1

• None.

Result: 

OK 

REPLACE ENGINE STOP AND START ECU. Refer to  REMOVAL [10/2022 - ] 

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR