POWER ASSIST SYSTEMS: POWER STEERING SYSTEM (for Gasoline Model (for Hatchback)): Check Assist Limit Record; 2019 - 2020 MY Corolla Corolla Hatchback GR Corolla [06/2018

Last Modified: 05-13-2024	6.11:8.1.0	Doc ID: RM100000001C0XE
Model Year Start: 2019	Model: GR Corolla	Prod Date Range: [06/2018 - 09/2019]
Title: POWER ASSIST SYSTEMS: POWER STEERING SYSTEM (for Gasoline Model (for Hatchback)): Check Assist Limit Record; 2019 - 2020 MY Corolla Corolla Hatchback GR Corolla [06/2018 - 09/2019]

Check Assist Limit Record

CAUTION / NOTICE / HINT

HINT:

Perform this troubleshooting procedure when no DTCs are output, including DTCs related to CAN communication system malfunctions.

PROCEDURE

1.	READ VALUE USING TECHSTREAM (ASSIST LIMIT RECORD 1)

(a) Using the Techstream, read the Data List item "Assist Limit Record 1".

Click here

Chassis > EMPS > Data List

Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
Assist Limit Record 1	Information of assist limit that was used in the past or is currently in use (latest history)	Unrec, Mtr Overheat, Pow Vol Low, Pow Vol Low Prevent, Eng Stall, Ready OFF, Mtr Overload, DC-DC Malf, Vhcl Spd Sig Malf, Batt Vol Keep	-	-

HINT:

For the Data List item "Assist Limit Record 1", each item in the Range is described below.

	Range	Description	Diagnostic Note
Assist Limit Record 1	Unrec	No assist limit. Continue with troubleshooting for "Heavy steering".	-
	Mtr Overheat	When the vehicle is stopped or traveling at low speed, and steering operations are performed repeatedly or the steering wheel is turned all the way to the side and held there for a long time, assist may be limited in order to prevent overheating of the power steering ECU with motor assembly. After 10 minutes elapse with the engine running and no steering operations being performed, the system will return to normal. After recovering from the overheated condition, assist can be performed as usual.	-
	Pow Vol Low	When insufficient battery charge, or battery degradation etc. causes the voltage to temporarily decrease, assist may be stopped. After the battery condition returns to normal, assist can be performed as usual.	-
	Pow Vol Low Prevent	When insufficient battery charge, or battery degradation etc. causes the voltage to temporarily decrease, assist may be limited. After the battery condition returns to normal, assist can be performed as usual.	-
	Eng Stall	When the engine stalls, battery charge becomes insufficient, so assist is stopped. After recovering from the engine stall, assist can be performed as usual.	-
	Ready OFF	After Ready ON, if a malfunction in the HV system etc. causes a return to Ready OFF, the HV battery charge becomes insufficient, so assist is stopped. After returning to Ready ON state, assist can be performed as usual.	Not displayed for this vehicle
	Mtr Overload	When the steering wheel cannot turn, such as when a road wheel is against a curb, if the driver continues to apply force to the steering wheel, current to the motor may be limited to prevent overheating. When the steering wheel is returned to a neutral position, assist can be performed as usual.	-
	DC-DC Malf	If there is a malfunction in the DC-DC converter, etc., assist may be limited. After the DC-DC converter returns to normal, assist can be performed as usual.	Not displayed for this vehicle
	Vhcl Spd Sig Malf	If the vehicle speed signal is abnormal due to a wheel speed sensor malfunction, etc., assist may be limited.	-
	Batt Vol Keep	When insufficient battery charge, or battery degradation etc. causes the voltage to temporarily decrease, assist may be limited. After the battery condition returns to normal, assist can be performed as usual.	-

Chassis > EMPS > Data List

Tester Display
Assist Limit Record 1

(b) Based on the "Assist Limit Record 1" information, the following Data List items and the information from the customer interview, explain the situation to the customer.

Chassis > EMPS > Data List

Tester Display
Record 1 Key Cycle
Record 1 Key Cycle Elapsed Time

HINT:

If it is necessary to investigate further into the past, check the "Assist Limit Record 2" and "Assist Limit Record 3" information in the same way as "Assist Limit Record 1".

END