Toyota Corolla Cross: ECU Internal Error (P164400)

Toyota Corolla Cross (2022-2024) Service Manual / Engine & Hybrid System / Stop And Start / Stop And Start System / ECU Internal Error (P164400)

DESCRIPTION

If a malfunction is detected in the starter circuit, the engine stop and start ECU stores DTC P164400.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	MIL	Warning Indicate	Note
P164400	ECU Internal Error	Both of the following conditions are met for 0.2 seconds or more (1 trip detection logic): Ignition switch ON. Malfunction in starter circuit (STA).	Wire harness or connector ST relay Engine stop and start ECU	Comes on (For Mexico Models: Does not come on)	Does not come on (For Mexico Models: Blinks)	SAE Code: P1644

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Warning Indicate

Note

P164400

ECU Internal Error

Both of the following conditions are met for 0.2 seconds or more (1 trip detection logic):

Ignition switch ON.
Malfunction in starter circuit (STA).

Wire harness or connector
ST relay
Engine stop and start ECU

Comes on (For Mexico Models: Does not come on)

Does not come on (For Mexico Models: Blinks)

SAE Code: P1644

MONITOR STRATEGY

Related DTCs	P1644: Engine stop and start ECU internal starter relay circuit functional
Required Sensors/Components (Main)	Engine stop and start ECU
Required Sensors/Components (Related)	-
Frequency of Operation	Continuous
Duration	1 second: Case2 0.2 seconds: Case1, Case3, Case4, Case5, Case6, Case7
MIL Operation	Immediate
Sequence of Operation	None

TYPICAL ENABLING CONDITIONS

All

All of the following conditions are met	-
Write Inhibit	permit
Time after Write status forbiddance to permit	0.5 seconds or more
Ignition switch	ON
Time after ignition switch is off to ON	0.5 seconds or more
A/D converter fail (P060B)	Not detected

Case1

All of the following conditions are met	-
Engine stop and start ECU internal high side switch for starter relay	OFF
Engine stop and start ECU internal low side switch for starter relay	OFF
Engine stop and start ECU internal limit switch for starter relay	OFF
Engine stop and start ECU starter relay terminal voltage level	High

Case2

All of the following conditions are met	-
Engine stop and start ECU internal high side switch for starter relay	OFF
Engine stop and start ECU internal low side switch for starter relay	OFF
Engine stop and start ECU internal limit switch for starter relay	OFF
Engine stop and start ECU starter relay terminal voltage level	Low

Case3

All of the following conditions are met	-
Engine stop and start ECU internal starter relay circuit check*	Activated
Engine stop and start ECU internal high side switch for starter relay	OFF
Engine stop and start ECU internal low side switch for starter relay	OFF
Engine stop and start ECU internal limit switch for starter relay	ON
Engine stop and start ECU starter relay terminal voltage level	Low

Case4

All of the following conditions are met	-
Engine stop and start ECU internal starter relay circuit check*	Activated
Engine stop and start ECU internal high side switch for starter relay	ON
Engine stop and start ECU internal low side switch for starter relay	OFF
Engine stop and start ECU internal limit switch for starter relay	ON

Case5

All of the following conditions are met	-
Engine stop and start ECU internal starter relay circuit check*	Activated
Engine stop and start ECU internal high side switch for starter relay	OFF
Engine stop and start ECU internal low side switch for starter relay	ON
Engine stop and start ECU internal limit switch for starter relay	ON
Engine stop and start ECU starter relay terminal voltage level	Low

Case6

All of the following conditions are met	-
Engine stop and start ECU internal high side switch for starter relay	ON
Engine stop and start ECU internal low side switch for starter relay	ON
Starter relay overcurrent	Not detected

Case7

Engine stop and start ECU internal high side switch for starter relay

OFF

*: All of the following conditions are met	-
Write Inhibit	permit
Time after Write status forbiddance to permit	0.5 seconds or more
Ignition switch	ON
Time after ignition switch is off to ON	0.5 seconds or more
Battery voltage	8 V or higher
A/D converter fail (P060B)	Not detected
Engine stop and start ECU internal starter relay circuit fail (P1644)	Not detected
Engine stop and start ECU processer fail (P0606)	Not detected
Lost communication with skid control ECU (brake actuator assembly) (U0129)	Not detected
Starter	OFF
Engine	Running
Fuel cut	OFF
One of the following conditions (a), (b) or (c) is met	-
(a) Shift position	D range
(b) Shift position	R range
(c) Shift position	S range
Vehicle speed	7 to 15 km/h (4.3 to 9.3 mph)
Engine stop and start ECU starter relay voltage	Higher than [Battery voltage x 0.44] V, and less than [Battery voltage x 0.88] V
Engine stop and start ECU internal high side switch for starter relay	OFF
Engine stop and start ECU internal low side switch for starter relay	OFF
Time after engine stop and start ECU internal limit switch for starter relay OFF to ON	0.3 seconds or more
Time after engine stop and start ECU internal high side switch for starter relay ON to OFF	0.05 seconds or more
Engine stop and start ECU internal limit switch for starter relay	ON
Time after engine stop and start ECU internal low side switch for starter relay ON to OFF	0.05 seconds or more
Time after engine stop and start ECU internal limit switch for starter relay ON to OFF	0.05 seconds or more

TYPICAL MALFUNCTION THRESHOLDS

Case 1, Case2, Case5

Engine stop and start ECU starter relay voltage

Higher than [Battery voltage x 0.44] V

Case 3

Either of the following conditions (a) or (b) is met	-
(a) Engine stop and start ECU starter relay voltage	[Battery voltage x 0.44] V or less
(b) Engine stop and start ECU starter relay voltage	[Battery voltage x 0.88] V or higher

Case 4

Engine stop and start ECU starter relay voltage

Less than [Battery voltage x 0.88] V

Case 6

Engine stop and start ECU starter relay terminal voltage level

Low

Case 6

Starter relay overcurrent

Detected

CONFIRMATION DRIVING PATTERN

HINT:

If the cable is disconnected from the auxiliary 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, by idling the engine for 5 to 60 minutes with the auxiliary battery fluid temperature at 11°C (52°F) or higher, the refresh charge will be completed.)
If the GTS is not available and the Data List item Status of Battery Charge Control cannot be checked, charge the auxiliary 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.
When clearing the permanent DTCs, refer to the "CLEAR PERMANENT DTC" procedure (except Mexico Models).
Click here
When clearing the permanent DTCs, do not disconnect the cable from the battery terminal or attempt to clear the DTCs during this procedure, as doing so will clear the universal trip and normal judgment histories (except Mexico Models).

CONFIRMATION AFTER TROUBLESHOOTING

(a) Clear the DTCs.

Powertrain > Stop and Start > Clear DTCs

(b) Start the engine and warm it up.

CAUTION:

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

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

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

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

(g) Check that DTCs are not output.

Powertrain > Stop and Start > Trouble Codes

STOP AND START SYSTEM OPERATION CHECK

Click here

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, perform learning of the external backup boost converter (eco run vehicle converter assembly).
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
When the engine stop and start ECU or oil pump with motor assembly is replaced, check the oil pump with motor assembly.
Click here
Inspect the fuses for circuits related to this system before performing the following procedure.

HINT:

Using the GTS, 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
If DTCs 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) and P164400 (ECU Internal Error) are output simultaneously, perform troubleshooting for DTC P060B1C, P060B49 or P060B71 first as it may have caused DTC P164400 to be stored.
Click here
If DTCs P061511 (Starter Relay Circuit Short to Ground) or P061515 (Starter Relay Circuit Short to Battery or Open) and P164400 (ECU Internal Error) are output simultaneously, perform troubleshooting for DTCs P061511 or P061515 first as it may have caused DTC P164400 to be stored.
Click here
For wire harness and connector inspection procedures and precautions, refer to " "
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.

PROCEDURE

1.	CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P164400)

(a) Read the DTCs.

Powertrain > Stop and Start > Trouble Codes

Result	Proceed to
DTC P164400 is output	A
DTCs P060B1C, P060B49 or P060B71 and P164400 are output	B
DTCs P061511 and P164400 are output	C
DTCs P061515 and P164400 are output	D

GO TO DTC P060B1C, P060B49 OR P060B71

GO TO DTC P061511

GO TO DTC P061515

2.	CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - ST RELAY)

(a) Disconnect the I223 certification ECU (smart key ECU assembly) connector.*1

*1: w/ Smart Key System

(b) Disconnect the I12 ignition or starter switch assembly connector.*1

*1: w/o Smart Key System

(d) Disconnect the A169 engine stop and start ECU connector.

(e) Remove the ST relay from the No. 1 engine room relay block.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
A169-21 (STA) - ST relay terminal 2	Always	Below 1 Ω
A169-21 (STA) - Body ground and other terminals	Always	10 kΩ or higher
ST relay terminal 2 - Body ground and other terminals	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

3.	CHECK HARNESS AND CONNECTOR (ENGINE STOP AND START ECU - PARK/NEUTRAL POSITION SWITCH ASSEMBLY)

(a) Disconnect the A169 engine stop and start ECU connector.

(b) Disconnect the C62 park/neutral position switch assembly connector.

*1: w/ Smart Key System

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
A169-21 (STA) - C62-5 (L)	Always	Below 1 Ω

REPAIR OR REPLACE HARNESS OR CONNECTOR

4.	INSPECT RELAY (ST RELAY)

(a) Inspect the ST relay.

Click here

REPLACE RELAY (ST RELAY)

5.	CHECK HARNESS AND CONNECTOR (ST RELAY - BODY GROUND)

(a) Remove the ST relay from the No. 1 engine room relay block.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
ST relay terminal 1 - Body ground	Always	Below 1 Ω

REPLACE ENGINE STOP AND START ECU

REPAIR OR REPLACE HARNESS OR CONNECTOR

SEE MORE:

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Toyota Corolla Cross: ECU Internal Error (P164400)

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