Lexus ES: Open or Short in Front Speed Sensor RH Circuit (C1405,C1406)
DESCRIPTION
Refer to DTCs C1413 and C1414.
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| DTC No. | Detection Item | INF Code | DTC Detection Condition | Trouble Area | MIL | Note |
|---|---|---|---|---|---|---|
| C1405 | Open or Short in Front Speed Sensor RH Circuit | 503 506 508 |
|
| Comes on |
|
| C1406 | Open or Short in Front Speed Sensor LH Circuit | 513 516 518 |
|
| Comes on |
|
MONITOR DESCRIPTION
The skid control ECU (brake booster with master cylinder assembly) monitors the output voltage and power supply voltage of the speed sensors. If the output voltage of the speed sensor is outside the normal range, or if the voltage at VM1 of the skid control ECU (brake booster with master cylinder assembly) is normal and the power supply voltage of the speed sensor drops below a specific value, the skid control ECU (brake booster with master cylinder assembly) judges that the circuit of the speed sensor is malfunctioning and illuminates the MIL and stores a DTC.
MONITOR STRATEGY
| Related DTCs | C0502: Speed sensor circuit low C0503: Speed sensor circuit high C0508: Speed sensor circuit low C0509: Speed sensor circuit high C14E1 (Case 1): Speed sensor voltage circuit low C14E1 (Case 2): Speed sensor voltage circuit low C14E4 (Case 1): Speed sensor voltage circuit low C14E4 (Case 2): Speed sensor voltage circuit low |
| Required Sensors/Components(Main) | Speed sensor Skid control ECU (brake booster with master cylinder assembly) |
| Required Sensors/Components(Related) | Speed sensor Skid control ECU (brake booster with master cylinder assembly) |
| Frequency of Operation | Continuous |
| Duration | 0.5 seconds: C0502, C0503, C0508, C0509, C14E1 (Case 1) and C14E4 (Case 1) 60 seconds: C14E1 (Case 2) and C14E4 (Case 2) |
| MIL Operation | Immediately |
| Sequence of Operation | None |
TYPICAL ENABLING CONDITIONS
C0502, C0503, C0508 and C0509| Monitor runs whenever the following DTCs are not stored | C14E1, C14E4, C14E7, C14EA (Case 1) (Speed sensor voltage circuit low) C14E1, C14E4, C14E7, C14EA (Case 2) (Speed sensor voltage circuit low) |
| All of the following conditions are met | - |
| Brake system voltage 1 (VM1) | Higher than 7.54 V |
| Serial communication with low side IC | Valid |
| Command to speed sensor power supply | On |
| Speed sensor fail (C14E1, C14E4, C14E7, C14EA) | Not detected |
| Monitor runs whenever the following DTCs are not stored | C0502, C0508, C050E, C0514 (Speed sensor circuit low) C0503, C0509, C050F, C0515 (Speed sensor circuit high) C14E1, C14E4, C14E7, C14EA (Case 2) (Speed sensor voltage circuit low) |
| All of the following conditions are met | - |
| Brake system voltage 1 (VM1) | Higher than 7.54 V |
| Serial communication with low side IC | Valid |
| Command to speed sensor power supply | On |
| Speed sensor fail (C0502, C0503, C0508, C0509, C050E, C050F, C0514, C0515, C14E1 (Case 2), C14E4 (Case 2), C14E7 (Case 2), C14EA (Case 2)) | Not detected |
| Monitor runs whenever the following DTCs are not stored | C0502, C0508, C050E, C0514 (Speed sensor circuit low) C0503, C0509, C050F, C0515 (Speed sensor circuit high) C14E1, C14E4, C14E7, C14EA (Case 1) (Speed sensor voltage circuit low) |
| All of the following conditions are met | - |
| Brake system voltage 1 (VM1) | Higher than 7.54 V |
| Serial communication with low side IC | Valid |
| Command to speed sensor power supply | On |
| Speed sensor fail (C0502, C0503, C0508, C0509, C050E, C050F, C0514, C0515, C14E1 (Case 1), C14E4 (Case 1), C14E7 (Case 1), C14EA (Case 1)) | Not detected |
TYPICAL MALFUNCTION THRESHOLDS
C0502 and C0508| Speed sensor voltage | Less than 0.4 V |
| Speed sensor voltage | Higher than 3.3 V |
| Speed sensor power supply voltage | Less than 6.1 V |
| The speed sensor power supply voltage drops below 6.1 V for 0.2 seconds or more | Met |
COMPONENT OPERATING RANGE
C0502, C0503, C0508 and C0509| Both of the following conditions are met | - |
| Serial communication with low side IC | Valid |
| Speed sensor voltage | 0.4 V or more, and 3.3 V or less |
| Both of the following conditions are met | - |
| Serial communication with low side IC | Valid |
| Speed sensor power supply voltage | 6.1 V or more |
| All of the following conditions are met | - |
| Brake system voltage 1 (VM1) | Higher than 7.54 V |
| Serial communication with low side IC | Valid |
| Command to speed sensor power supply | On |
| Speed sensor fail (C0502, C0503, C0508, C0509, C050E, C050F, C0514, C0515, C14E1 (Case 1), C14E4 (Case 1), C14E7 (Case 1), C14EA (Case 1)) | Not detected |
| The speed sensor power supply voltage drops below 6.1 V for 0.2 seconds or more | Not met |
CONFIRMATION DRIVING PATTERN
- Connect the Techstream to the DLC3.
- Turn the power switch on (IG).
- Turn the Techstream on.
- Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
- Turn the power switch off.
- Turn the power switch on (IG).
- Turn the Techstream on.
- Wait 60 seconds.
- Enter the following menus: Chassis / ABS/VSC/TRAC / Trouble Codes.
-
Read the DTCs.
HINT:
- If a DTC is output, the system is malfunctioning.
- If a DTC is not output, perform the following procedure.
-
If the DTCs are not output, perform a universal trip and check for permanent DTCs.
Click here
HINT:
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTCs are output, the system is normal.
WIRING DIAGRAM
Refer to DTCs C1413 and C1414.
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CAUTION / NOTICE / HINT
NOTICE:
After replacing the skid control ECU (brake booster with master cylinder assembly), perform linear solenoid valve offset learning, ABS holding solenoid valve learning, yaw rate and acceleration sensor zero point calibration and system information memorization after performing "Reset Memory".
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PROCEDURE
| 1. | CHECK DTC |
(a) Clear the DTCs.
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(b) Turn the power switch off.
(c) Turn the power switch on (IG).
(d) Check if the same DTC is output.
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| Result | Proceed to |
|---|---|
| DTC C1405 is output. | A |
| DTC C1406 is output. | B |
| B |  | GO TO STEP 7 |
|
| 2. | READ VALUE USING TECHSTREAM (MOMENTARY INTERRUPTION) |
(a) Using the Techstream, check for any momentary interruptions in the wire harness and connector corresponding to a DTC.
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| Tester Display | Measurement Item | Range | Normal Condition | Diagnostic Note |
|---|---|---|---|---|
| FR Speed Open | Front speed sensor RH open detection | Error or Normal | Error: Momentary interruption Normal: Normal | - |
| Tester Display |
|---|
| FR Speed Open |
(b) Check for any momentary interruptions in the wire harness and connectors.
OK:
There are no momentary interruptions.
NOTICE:
Perform the above inspection before removing the sensor and connector.
| NG | | GO TO STEP 5 |
|
| 3. | READ VALUE USING TECHSTREAM (FRONT SPEED SENSOR RH) |
(a) Select the Data List on the Techstream.
Click here
| Tester Display | Measurement Item | Range | Normal Condition | Diagnostic Note |
|---|---|---|---|---|
| FR Wheel Speed | Front speed sensor RH | Min.: 0 km/h (0 mph), Max.: 326.4 km/h (203 mph) | Vehicle stopped: 0 km/h (0 mph) | When driving at constant speed: No large fluctuations |
| Tester Display |
|---|
| FR Wheel Speed |
(b) Check the front speed sensor RH output value.
OK:
The output value changes in accordance with the vehicle speed.
| NG | | GO TO STEP 5 |
|
| 4. | RECONFIRM DTC |
(a) Clear the DTCs.
Click here
(b) Turn the power switch off.
(c) Turn the power switch on (READY).
(d) Perform a road test.
(e) Check if the same DTC is output.
Click here
| Result | Proceed to |
|---|---|
| DTC C1405 is not output. | A |
| DTC C1405 is output. | B |
| A | | USE SIMULATION METHOD TO CHECK |
| B | | REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY |
| 5. | CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY - FRONT SPEED SENSOR RH) |
(a) Turn the power switch off.
(b) Make sure that there is no looseness at the locking part and the connecting part of the connectors.
OK:
The connector is securely connected.
(c) Disconnect the A45 skid control ECU (brake booster with master cylinder assembly) connector.
(d) Disconnect the A46 front speed sensor RH connector.
(e) Check both the connector case and the terminals for deformation and corrosion.
OK:
No deformation or corrosion.
(f) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| A45-3 (FR+) - A46-1 (FR+) | Always | Below 1 Ω |
| A45-3 (FR+) or A46-1 (FR+) - Body ground | Always | 10 kΩ or higher |
| A45-4 (FR-) - A46-2 (FR-) | Always | Below 1 Ω |
| A45-4 (FR-) or A46-2 (FR-) - Body ground | Always | 10 kΩ or higher |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
| 6. | INSPECT BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (SENSOR OUTPUT) |
| (a) Reconnect the A45 skid control ECU (brake booster with master cylinder assembly) connector. |
|
(b) Turn the power switch on (IG).
(c) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| A46-1 (FR+) - Body ground | Power switch on (IG) | 8 to 14 V |
NOTICE:
Check the front speed sensor RH signal after replacement.
Click here
| OK | | REPLACE FRONT SPEED SENSOR RH |
| NG | | REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY |
| 7. | READ VALUE USING TECHSTREAM (MOMENTARY INTERRUPTION) |
(a) Using the Techstream, check for any momentary interruptions in the wire harness and connector corresponding to a DTC.
Click here
| Tester Display | Measurement Item | Range | Normal Condition | Diagnostic Note |
|---|---|---|---|---|
| FL Speed Open | Front speed sensor LH open detection | Error or Normal | Error: Momentary interruption Normal: Normal | - |
| Tester Display |
|---|
| FL Speed Open |
(b) Check for any momentary interruptions in the wire harness and connectors.
OK:
There are no momentary interruptions.
NOTICE:
Perform the above inspection before removing the sensor and connector.
| NG | | GO TO STEP 10 |
|
| 8. | READ VALUE USING TECHSTREAM (FRONT SPEED SENSOR LH) |
(a) Select the Data List on the Techstream.
Click here
| Tester Display | Measurement Item | Range | Normal Condition | Diagnostic Note |
|---|---|---|---|---|
| FL Wheel Speed | Front speed sensor LH | Min.: 0 km/h (0 mph), Max.: 326.4 km/h (203 mph) | Vehicle stopped: 0 km/h (0 mph) | When driving at constant speed: No large fluctuations |
| Tester Display |
|---|
| FL Wheel Speed |
(b) Check the front speed sensor LH output value.
OK:
The output value changes in accordance with the vehicle speed.
| NG | | GO TO STEP 10 |
|
| 9. | RECONFIRM DTC |
(a) Clear the DTCs.
Click here
(b) Turn the power switch off.
(c) Turn the power switch on (READY).
(d) Perform a road test.
(e) Check if the same DTC is output.
Click here
| Result | Proceed to |
|---|---|
| DTC C1406 is not output. | A |
| DTC C1406 is output. | B |
| A | | USE SIMULATION METHOD TO CHECK |
| B | | REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY |
| 10. | CHECK HARNESS AND CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY - FRONT SPEED SENSOR LH) |
(a) Turn the power switch off.
(b) Make sure that there is no looseness at the locking part and the connecting part of the connectors.
OK:
The connector is securely connected.
(c) Disconnect the A45 skid control ECU (brake booster with master cylinder assembly) connector.
(d) Disconnect the A48 front speed sensor LH connector.
(e) Check both the connector case and the terminals for deformation and corrosion.
OK:
No deformation or corrosion.
(f) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| A45-31 (FL+) - A48-1 (FL+) | Always | Below 1 Ω |
| A45-31 (FL+) or A48-1 (FL+) - Body ground | Always | 10 kΩ or higher |
| A45-32 (FL-) - A48-2 (FL-) | Always | Below 1 Ω |
| A45-32 (FL-) or A48-2 (FL-) - Body ground | Always | 10 kΩ or higher |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
| 11. | INSPECT BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (SENSOR OUTPUT) |
| (a) Reconnect the A45 skid control ECU (brake booster with master cylinder assembly) connector. |
|
(b) Turn the power switch on (IG).
(c) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| A48-1 (FL+) - Body ground | Power switch on (IG) | 8 to 14 V |
NOTICE:
Check the front speed sensor LH signal after replacement.
Click here
| OK | | REPLACE FRONT SPEED SENSOR LH |
| NG | | REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY |
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Front Speed Sensor RH Circuit Output (C1413,C1414)
DESCRIPTION Each speed sensor detects the wheel speed and sends the signals to the skid control ECU (brake booster with master cylinder assembly). These signals are used for ABS control. HINT: The out
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