STOP AND START: STOP AND START SYSTEM: P16449E; ECU Malfunction (Low Voltage Signal) Stuck On; 2019 - 2023 MY RAV4 [11/2018

Last Modified: 01-30-2024	6.11:8.1.0	Doc ID: RM100000001EEKG
Model Year Start: 2019	Model: RAV4	Prod Date Range: [11/2018 - 10/2023]
Title: STOP AND START: STOP AND START SYSTEM: P16449E; ECU Malfunction (Low Voltage Signal) Stuck On; 2019 - 2023 MY RAV4 [11/2018 - 10/2023]

DTC

P16449E

ECU Malfunction (Low Voltage Signal) Stuck On

DESCRIPTION

The engine stop and start ECU detects abnormalities in the DI (+B) value that is input from the integrated IC (stop and start backup boost converter integrated IC) to the CPU.

If a logical inconsistency occurs between the +B value and DI (+B) value input to the CPU, the engine stop and start ECU stores DTC P16449E and blinks the stop and start cancel indicator.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Warning Indicate	Memory	Note
P16449E	ECU Malfunction (Low Voltage Signal) Stuck On	Both of the following conditions are met for 1 second or more (1 trip detection logic): +B terminal voltage is 9.16 V or more. Low battery voltage is detected.	Wire harness or connector Engine stop and start ECU	Blinks	DTC stored	SAE Code: P1644

CONFIRMATION DRIVING PATTERN

CONFIRMATION AFTER TROUBLESHOOTING

HINT:

If the cable is disconnected from the battery terminal, stop and start control is prohibited until refresh charge is completed.
In this case, let the vehicle idle to complete the refresh charge. The refresh charge is complete when the Data List item "Status of Battery Charge Control" changes from "Refresh Charge Mode". (Usually, idling the engine for 5 to 60 minutes with the battery fluid temperature at 11°C (51°F) or higher, the refresh charge will be completed.)
If the Techstream is not available and the Data List item "Status of Battery Charge Control" cannot be checked, charge the battery by idling the engine for approximately 5 to 60 minutes or driving the vehicle, and then drive the vehicle and check that stop and start control operates.
If the engine is started with the hood open, the system determines that a jump start has occurred. Therefore, make sure that the hood is closed before starting the engine and driving the vehicle.
After the refresh charge completes, turn the ignition switch off, wait for at least 30 seconds, and then start the engine again. If the vehicle enters refresh charge mode again while the engine is idling, the initial refresh charge did not properly complete, so wait for the refresh charge to complete.
Allow the engine to idle for 3 minutes after it is warmed up and check that the engine idle speed is within 50 rpm of the target idle speed.

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(d) Clear the DTCs.

Powertrain > Stop and Start > Clear DTCs

(e) Start the engine and warm it up.

(f) Drive the vehicle at 7 km/h (4 mph) or more.

CAUTION:

When performing Confirmation Driving Pattern, obey all speed limits and traffic laws.

(g) Depress the brake pedal and stop the vehicle.

(h) Keep the engine stopped by stop and start control for 1 second or more. (Keep the shift lever in D.)

(i) Release the brake pedal with the shift lever in D to start the engine.

HINT:

If the engine cranks slowly when the engine is restarted, it can be determined that the battery voltage is low.

(j) Check that DTCs are not output.

Powertrain > Stop and Start > Trouble Codes

STOP AND START SYSTEM OPERATION CHECK

HINT:

If the cable is disconnected from the battery terminal, stop and start control is prohibited until refresh charge is completed.
In this case, let the vehicle idle to complete the refresh charge. The refresh charge is complete when the Data List item "Status of Battery Charge Control" changes from "Refresh Charge Mode". (Usually, idling the engine for 5 to 60 minutes with the battery fluid temperature at 11°C (51°F) or higher, the refresh charge will be completed.)
If the Techstream is not available and the Data List item "Status of Battery Charge Control" cannot be checked, charge the battery by idling the engine for approximately 5 to 60 minutes or driving the vehicle, and then drive the vehicle and check that stop and start control operates.
If the engine is started with the hood open, the system determines that a jump start has occurred. Therefore, make sure that the hood is closed before starting the engine and driving the vehicle.
After the refresh charge completes, turn the ignition switch off, wait for at least 30 seconds, and then start the engine again. If the vehicle enters refresh charge mode again while the engine is idling, the initial refresh charge did not properly complete, so wait for the refresh charge to complete.

(a) Start the engine and warm it up.

(b) Turn the air conditioning system off.

CAUTION:

When performing Confirmation Driving Pattern, obey all speed limits and traffic laws.

(d) Depress the brake pedal and stop the vehicle.

(e) Allow the engine to stop by stop and start control. (Keep the shift lever in D.)

(f) Release the brake pedal with the shift lever in D to start the engine.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Before replacing the engine stop and start ECU, read the number of starter operations and write it into a new engine stop and start ECU.
Click here
After replacing the engine stop and start ECU or air conditioning amplifier assembly, reset and perform learning of the air conditioning information in the engine stop and start ECU.
Click here
After replacing the engine stop and start ECU or airbag ECU assembly, clear and calibrate the deceleration sensor zero point in the engine stop and start ECU.
Click here
When the engine stop and start ECU or oil pump with solenoid assembly is replaced, check the oil pump with solenoid assembly.
Click here
Inspect the fuses for circuits related to this system before performing the following procedure.

HINT:

If DTCs P16449E (ECU Malfunction (Low Voltage Signal) Stuck On) and P060B1C (Analog to Digital Converter Circuit Voltage Out of Range), P060B49 (Analog to Digital Converter Internal Electronic Failure) or P060B71 (Analog to Digital Converter Actuator Stuck) are output simultaneously, perform troubleshooting for DTC P060B1C, P060B49 or P060B71 first as it may have caused DTC P16449E to be stored.
Click here
Using the Techstream, read the freeze frame data before troubleshooting. System condition information is recorded as freeze frame data the moment a DTC is stored. This information can be useful when troubleshooting.
Click here
DTCs for the stop and start system are not cleared even if the malfunction has been repaired. After repairing the malfunction, be sure to clear the DTCs.
Click here

PROCEDURE

1.	CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P16449E)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(d) Enter the following menus: Powertrain / Stop and Start / Trouble Codes.

(e) Read the DTCs.

Powertrain > Stop and Start > Trouble Codes

Result	Proceed to
DTC P16449E is output	A
DTC P16449E and P060B1C, P060B49 or P060B71 are output	B

HINT:

If DTCs P16449E and P060B1C, P060B49 or P060B71 are output simultaneously, troubleshoot for DTC P060B1C, P060B49 or P060B71 first.

GO TO DTC P060B1C, P060B49 OR P060B71

2.	CHECK HARNESS AND CONNECTOR (+B TERMINAL POWER SOURCE CIRCUIT)

*a	Front view of wire harness connector (to Engine Stop and Start ECU)

(a) Disconnect the engine stop and start ECU connector.

(b) Turn the ignition switch to ON.

Standard Voltage:

Tester Connection	Condition	Specified Condition
A34-1 (+B) - Body ground	Ignition switch ON	9.5 to 14 V

REPAIR OR REPLACE HARNESS OR CONNECTOR (ENGINE STOP AND START ECU - EFI-MAIN NO. 1 RELAY)

3.	CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - BODY GROUND)

(a) Disconnect the engine stop and start ECU connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
A34-6 (DGND) - Body ground	Always	Below 1 Ω

REPLACE ENGINE STOP AND START ECU

REPAIR OR REPLACE HARNESS OR CONNECTOR