Variable Gear Ratio Steering System (Diagnostic Codes & Symptom Tests): Diagnosis Lexus GS III рестайлинг

INSPECTION PROCEDURE

HINT

When DTC C15A2/62 is output, a short circuit inside the steering actuator or inside the steering control ECU is suspected.

Scheme 40

Scheme 41

1. CHECK WIRE HARNESS (STEERING CONTROL ECU - STEERING ACTUATOR) Turn the power switch OFF. Disconnect the K69 steering control ECU connector. Disconnect the K26 steering actuator connector. Measure the resistance of the wire harness side connectors. Standard resistance Tester Connection Specified Condition K69-1 (BMV) - K69-2 (BMU) 10 kohms or higher K69-1 (BMV) - K69-3 (BMW) 10 kohms or higher K69-2 (BMU) - K69-3 (BMW) 10 kohms or higher K69-1 (BMV) - K26-5 (BMV+) Below 1 ohms K69-2 (BMU) - K26-4 (BMU+) Below 1 ohms K69-3 (BMW) - K26-13 (BMW+) Below 1 ohms K69-1 (BMV) - Body ground 10 kohms or higher K69-2 (BMU) - Body ground 10 kohms or higher K69-3 (BMW) - Body ground 10 kohms or higher NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
2. CHECK STEERING ACTUATOR Disconnect the K69 steering control ECU connector. HINT: The resistance must be measured after the steering actuator connector is connected. Measure the resistance of the wire harness side connector. Standard resistance Tester Connection Specified Condition K69-1 (BMV) - K69-2 (BMU) Below 1 ohms K69-1 (BMV) - K69-3 (BMW) Below 1 ohms K69-2 (BMU) - K69-3 (BMW) Below 1 ohms K69-1 (BMV) - Body ground 10 kohms or higher K69-2 (BMU) - Body ground 10 kohms or higher K69-3 (BMW) - Body ground 10 kohms or higher NG --> REPLACE STEERING ACTUATOR OK --> REPLACE STEERING CONTROL ECU

HINT

The actuator only can be checked in this procedure. If it is normal, the steering control ECU is faulty.

Scheme 42

1. CHECK WIRE HARNESS (POWER SOURCE CIRCUIT) Turn the power switch OFF. Measure the resistance of the A40 steering control ECU connector. Standard resistance Tester Connection Specified Condition A40-7 (PGND) - Body ground Below 1 ohms Turn the power switch ON (IG). Measure the voltage of the A40 steering control ECU connector. Standard voltage Tester Connection Specified Condition A40-8 (PIG) - Body ground 10 to 14 V NG --> REPAIR OR REPLACE HARNESS OR FUSE OK: Go to next step
2. CHECK WIRE HARNESS (STEERING CONTROL ECU - STEERING ACTUATOR) Turn the power switch OFF. Disconnect the K69 steering control ECU connector. Disconnect the K26 steering actuator connector. Measure the resistance of the wire harness side connectors. Standard resistance Tester Connection Specified Condition K69-1 (BMV) - K69-2 (BMU) 10 kohms or higher K69-1 (BMV) - K69-3 (BMW) 10 kohms or higher K69-2 (BMU) - K69-3 (BMW) 10 kohms or higher K69-1 (BMV) - K26-5 (BMV+) Below 1 ohms K69-2 (BMU) - K26-4 (BMU+) Below 1 ohms K69-3 (BMW) - K26-13 (BMW+) Below 1 ohms K69-1 (BMV) - Body ground 10 kohms or higher K69-2 (BMU) - Body ground 10 kohms or higher K69-3 (BMW) - Body ground 10 kohms or higher NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
3. CHECK STEERING ACTUATOR Disconnect the K69 steering control ECU connector. HINT: The resistance must be measured after the steering actuator connector is connected. Measure the resistance of the wire harness side connector. Standard resistance Tester Connection Specified Condition K69-1 (BMV) - K69-2 (BMU) Below 1 ohms K69-1 (BMV) - K69-3 (BMW) Below 1 ohms K69-2 (BMU) - K69-3 (BMW) Below 1 ohms K69-1 (BMV) - Body ground 10 kohms or higher K69-2 (BMU) - Body ground 10 kohms or higher K69-3 (BMW) - Body ground 10 kohms or higher NG --> REPLACE STEERING ACTUATOR OK: Go to next step
4. CHECK DTC Connect the Techstream to the DLC3. Turn the power switch ON (IG) and turn the Techstream on. Check for DTCs. Refer to «DTC CHECK / CLEAR»(ref-386975-S17151165742011022400000) . Result Result Proceed to C15A1/61 is not output OK C15A1/61 is output NG NG --> REPLACE STEERING ACTUATOR OK --> REPLACE STEERING CONTROL ECU

HINT

The fault may be intermittent. Check harnesses and connectors thoroughly and retest.

Scheme 43

1. CHECK STEERING CONTROL ECU (POWER SOURCE CIRCUIT) Record and clear the DTCs. Refer to «DTC CHECK / CLEAR»(ref-386975-S17151165742011022400000) . Start the engine. Measure the voltage of the steering control ECU. Standard voltage Tester Connection Specified Condition Proceed to A40-3 (IG) - A40-7 (PGND) 9 to 16 V A A40-3 (IG) - A40-7 (PGND) Below 9 V B A40-3 (IG) - A40-7 (PGND) Above 16 V C C --> CHECK AND REPAIR CHARGING SYSTEM B --> CHECK OR REPAIR HARNESS AND FUSE A: Go to next step
2. CHECK DTC Turn the power switch OFF. Connect the Techstream to the DLC3. Turn the power switch ON (IG) and turn the Techstream on. Check for DTCs. Refer to «DTC CHECK / CLEAR»(ref-386975-S17151165742011022400000) . Result Result Proceed to C15C6/77 is not output OK C15C6/77 is output NG NG --> REPLACE STEERING CONTROL ECU OK --> END

HINT

The fault may be intermittent. Check harnesses and connectors thoroughly and retest.

Scheme 44

Scheme 45

1. CHECK WIRE HARNESS (STEERING CONTROL ECU - BODY GROUND) Turn the power switch OFF. Disconnect the negative (-) terminal cable from the battery. Disconnect the A40 steering control ECU connector. Measure the resistance of the wire harness side connector. Standard resistance Tester Connection Condition Specified Condition A40-7 (PGND) - Body ground Always Below 1 ohms NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
2. CHECK STEERING CONTROL ECU (POWER SOURCE CIRCUIT) Connect the negative (-) terminal cable to the battery. Record and clear the DTCs. Refer to «DTC CHECK / CLEAR»(ref-386975-S17151165742011022400000) . Start the engine. Measure the voltage of the steering control ECU. Standard voltage Tester Connection Specified Condition Proceed to A40-8 (PIG) - A40-7 (PGND) 9 to 16 V A A40-8 (PIG) - A40-7 (PGND) Below 9 V B A40-8 (PIG) - A40-7 (PGND) Above 16 V C C --> CHECK OR REPAIR CHARGING SYSTEM B --> CHECK OR REPAIR HARNESS AND FUSE A: Go to next step
3. CHECK DTC Turn the power switch OFF. Connect the Techstream to the DLC3. Turn the power switch ON (IG) and turn the Techstream on. Check for DTCs. Refer to «DTC CHECK / CLEAR»(ref-386975-S17151165742011022400000) . Result Result Proceed to Neither C15C7/78 nor C15C8/79 is output OK C15C7/78 or C15C8/79 is output NG NG --> REPLACE STEERING CONTROL ECU OK --> END

This problem may be caused by a malfunction in the electronically controlled brake system or EPS system. Make sure that no DTC is output for the skid control ECU, power steering ECU, or steering control ECU before proceeding with the following procedures.

If a DTC is output for any of these ECUs, first troubleshoot it and then proceed to the troubleshooting below.

HINT

This problem may be caused by a malfunction in the electronically controlled brake system or EPS system.

Make sure that no DTC is output for the skid control ECU, power steering ECU, or steering control ECU before proceeding with the following procedures.

If a DTC is output for any of these ECUs, first troubleshoot it and then proceed to the troubleshooting below.

Scheme 46

1. READ VALUE OF TECHSTREAM Connect the Techstream to the DLC3. Turn the power switch ON (IG). Turn the Techstream on. Enter the following menus: Chassis / VGRS / Data List. VGRS Tester Display Measurement Item/Range Normal Condition Motor Overheat Record Record of continuous overheat preventive control / Rec or Unrec Rec or Unrec Result Result Proceed to "Rec" (Record motor overheating) A "Unrec" (No record of motor overheating) B HINT: If "Rec" is displayed, reset the setting to "Unrec". Enter the VGRS menu on the Techstream, select record clearance, and follow the prompts to set to "Unrec". B --> See step 3 A: Go to next step
2. CHECK HEAT PROTECTION FUNCTION FOR STEERING ACTUATOR Turn the power switch ON (IG) and wait for 30 minutes until the steering actuator cools down. Start the engine and slowly turn the steering wheel from lock to lock (approximately 90°/sec) 3 times. HINT: If turning the steering wheel quickly while driving at low speeds, the steering angle may differ between left and right, or the steering wheel may become off-center. However, this is not a malfunction. Check the number of turns from lock to lock. Result Result Proceed to 3.2 turns A 2.7 turns B B --> VGRS SYSTEM IS NORMAL A: Go to next step
3. CHECK STEERING EFFORT Start the engine. Turn the steering wheel. Check the steering effort. OK Below 6.5 N*m (66 kgf*cm, 57 in.*lbf) HINT: After completing the inspection or repair, attempt to simulate the problem and then perform step 1 above again to reconfirm that the problem does not occur. NG --> GO TO THE APPROPRIATE POWER STEERING SERVICE INFORMATION OK: Go to next step
4. CHECK STEERING ACTUATOR Check for an abnormal noise or vibration in the steering actuator. OK Neither an abnormal noise or vibration occurs. NG --> See step 6 OK: Go to next step
5. CHECK STEERING CONTROL ECU (POWER SOURCE CIRCUIT) Turn the power switch ON (IG). Measure the voltage of the steering control ECU. Standard voltage Tester Connection Condition Specified Condition A40-3 (IG) - Body ground Power switch ON (IG) 10 to 14 V A40-8 (PIG) - Body ground Power switch ON (IG) 10 to 14 V Turn the power switch OFF. Measure the resistance of the steering control ECU. Standard resistance Tester Connection Condition Specified Condition A40-7 (PGND) - Body ground Always Below 1 ohms NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK --> REPLACE STEERING CONTROL ECU
6. GO TO STEERING WHEEL VIBRATES OR ABNORMAL NOISE IS HEARD FROM STEERING WHEEL. Refer to «Steering Wheel Vibrates or Abnormal Noise is Heard from Steering Wheel»(ref-387143-S26249055082011022400000)

HINT

1. Check that the steering wheel is centered.
2. After checking that no DTC is output for the VGRS system, perform the following procedure.

HINT

Check that no DTC is output for the VGRS system and electronically controlled brake system.

HINT

Check that there is no problem in CAN and BEAN communications before performing the following procedure.

If there are any problems in these communications, first troubleshoot then and then proceed to the troubleshooting below.