Safety Warning
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DTC U1177-87: Lost Communication with Side Obstacle Detection Control Module "A" (ch2) Missing Message; DTC U1178-87: Lost Communication with Side Obstacle Detection Control Module "B" (ch2) Missing Message [11/2023 - ]: Procedure
- CHECK FOR DTC
- Using the GTS, check for parking support brake system DTCs.
Body Electrical > Clearance Warning > Trouble Codes
Result
Result Proceed to No DTCs are output A DTC U1177-87 only is output B DTC U1178-87 only is output C DTC U1177-87 and U1178-87 are output D
Result:
A
USE SIMULATION METHOD TO CHECK
Refer to HOW TO PROCEED WITH TROUBLESHOOTING [12/2019 - ]
Result:
C
See step 4
Result:
D
See step 6
Result:
B
See step 2
- Using the GTS, check for parking support brake system DTCs.
- CHECK HARNESS AND CONNECTOR (BLIND SPOT MONITOR SENSOR RH (A) - BODY GROUND)
- Disconnect the connector of the blind spot monitor sensor RH (A).
*a Front view of wire harness connector
(to Blind Spot Monitor Sensor RH (A)) - Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection Condition Specified Condition M2-10 (BRGD) - Body ground Always Below 1 Ω Result
Proceed to OK NG
Result:
NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
Result:
OK
See step 3
- Disconnect the connector of the blind spot monitor sensor RH (A).
- CHECK HARNESS AND CONNECTOR (BLIND SPOT MONITOR SENSOR RH (A) - POWER SOURCE)
- Disconnect the blind spot monitor sensor RH (A) connector.
*a Front view of wire harness connector
(to Blind Spot Monitor Sensor RH (A)) - Measure the voltage according to the value(s) in the table below.
Standard Voltage
Tester Connection Switch Condition Specified Condition M2-5 (BRB) - Body ground Ignition switch ON 11 to 14 V M2-5 (BRB) - Body ground Ignition switch off Below 1 V Result
Proceed to OK NG
Result:
OK
REPLACE BLIND SPOT MONITOR SENSOR RH (A)
Refer to REMOVAL [11/2023 - ]
Result:
NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
- Disconnect the blind spot monitor sensor RH (A) connector.
- CHECK HARNESS AND CONNECTOR (BLIND SPOT MONITOR SENSOR LH (B) - BODY GROUND)
- Disconnect the connector of the blind spot monitor sensor LH (B) connector.
*a Front view of wire harness connector
(to Blind Spot Monitor Sensor LH (B)) - Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection Condition Specified Condition M43-10 (BLGD) - Body ground Always Below 1 Ω Result
Proceed to OK NG
Result:
NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
Result:
OK
See step 5
- Disconnect the connector of the blind spot monitor sensor LH (B) connector.
- CHECK HARNESS AND CONNECTOR (BLIND SPOT MONITOR SENSOR LH (B) - POWER SOURCE)
- Disconnect the connector of the blind spot monitor sensor LH (B).
*a Front view of wire harness connector
(to Blind Spot Monitor Sensor LH (B)) - Measure the voltage according to the value(s) in the table below.
Standard Voltage
Tester Connection Switch Condition Specified Condition M43-5 (BLB) - Body ground Ignition Switch ON 11 to 14 V M43-5 (BLB) - Body ground Ignition switch off Below 1 V Result
Proceed to OK NG
Result:
OK
REPLACE BLIND SPOT MONITOR SENSOR LH (B)
Refer to REMOVAL [11/2023 - ]
Result:
NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
- Disconnect the connector of the blind spot monitor sensor LH (B).
- CHECK CAN BUS (CONFIRM PROBLEM SYMPTOMS)
- Turn the ignition switch off.
- Disconnect the cable from the negative (-) auxiliary battery terminal.
- Measure the resistance according to the value(s) in the table below.
*a Component with wire harness connected
(Clearance warning ECU Assembly)*1 DLC3 Standard Resistance
Tester Connection Condition Specified Condition Problem Symptom if Specified Condition Not Met H46-37 (CANH) - H46-38 (CANL) Disconnect cable from negative (-) auxiliary battery terminal 54 to 69 Ω Below 54 Ω: Short in line 70 Ω or higher: Open in main line H46-37 (CANH) - Body ground Disconnect cable from negative (-) auxiliary battery terminal 200 Ω or higher Below 200 Ω: Short to ground H46-38 (CANL) - Body ground Disconnect cable from negative (-) auxiliary battery terminal 200 Ω or higher Below 200 Ω: Short to ground H46-37 (CANH) - H56-16 (BAT) Disconnect cable from negative (-) auxiliary battery terminal 6 kΩ or higher Below 6 kΩ: Short to +B H46-38 (CANL) - H56-16 (BAT) Disconnect cable from negative (-) auxiliary battery terminal 6 kΩ or higher Below 6 kΩ: Short to +B Result
Result Proceed to OK A NG (open in main line) B NG (short in line) C NG (short to +B or ground) D
Result:
B
See step 9
Result:
C
See step 13
Result:
D
See step 17
Result:
A
See step 7
- CLEAR DTCS
- Using the GTS, clear the DTCs.
Body Electrical > Clearance Warning > Clear DTCs
Result
Proceed to NEXT
Result:
NEXT
See step 8
- Using the GTS, clear the DTCs.
- CHECK FOR DTC
- Check for DTCs.
Body Electrical > Clearance Warning > Trouble Codes
Result
Result Proceed to DTC U1177-87 and U1178-87 are output A DTC U1177-87 and U1178-87 are not output B
Result:
A
REPLACE CLEARANCE WARNING ECU ASSEMBLY
Refer to REMOVAL [11/2023 - ]
Result:
B
GO TO PROBLEM SYMPTOM SIMULATION METHOD
Refer to PROBLEM SYMPTOMS TABLE [11/2023 - ]
- Check for DTCs.
- CHECK FOR OPEN IN CAN BUS WIRE (NO. 22 JUNCTION CONNECTOR)
- Disconnect the No. 22 CAN junction connector.
*a Front view of wire harness connector
(to No. 22 CAN Junction Connector)*b to Clearance Warning ECU Assembly CAN Wire *c to Blind Spot Monitor Sensor RH (A) CAN Main Wire *d to Blind Spot Monitor Sensor LH (B) CAN Main Wire - Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection Condition Specified Condition M34-3 (CANH) - M34-14 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher M34-2 (CA2P) - M34-13 (CA2N) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω M34-1 (CA2P) - M34-12 (CA2N) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Result
Result Proceed to OK A NG (to blind spot monitor sensor LH (B) CAN main wire) B NG (to blind spot monitor sensor RH (A) CAN main wire) C NG (to clearance warning ECU assembly CAN wire) D
Result:
A
REPLACE NO. 22 CAN JUNCTION CONNECTOR
Result:
C
See step 11
Result:
D
See step 12
Result:
B
See step 10
- Disconnect the No. 22 CAN junction connector.
- CHECK FOR OPEN IN CAN BUS MAIN WIRE (BLIND SPOT MONITOR SENSOR LH (B))
- Reconnect the M34 No. 22 CAN junction connector.
*a Front view of wire harness connector
(to Blind Spot Monitor Sensor LH (B)) - Disconnect the M43 blind spot monitor sensor LH (B) connector.
- Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection Condition Specified Condition M43-1 (CA2P) - M43-6 (CA2N) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Result
Proceed to OK NG
Result:
OK
REPLACE BLIND SPOT MONITOR SENSOR LH (B)
Refer to REMOVAL [11/2023 - ]
Result:
NG
REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (BLIND SPOT MONITOR SENSOR LH (B) - NO. 22 CAN JUNCTION CONNECTOR)
- Reconnect the M34 No. 22 CAN junction connector.
- CHECK FOR OPEN IN CAN BUS MAIN WIRE (BLIND SPOT MONITOR SENSOR RH (A))
- Reconnect the M34 No. 22 CAN junction connector.
*a Front view of wire harness connector
(to Blind Spot Monitor Sensor RH (A)) - Disconnect the M2 blind spot monitor sensor RH (A) connector.
- Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection Condition Specified Condition M2-1 (CA2P) - M2-6 (CA2N) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Result
Proceed to OK NG
Result:
OK
REPLACE BLIND SPOT MONITOR SENSOR RH (A)
Refer to REMOVAL [11/2023 - ]
Result:
NG
REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (BLIND SPOT MONITOR SENSOR RH (A) - NO. 22 CAN JUNCTION CONNECTOR)
- Reconnect the M34 No. 22 CAN junction connector.
- CHECK FOR OPEN IN CAN BUS WIRE (CLEARANCE WARNING ECU ASSEMBLY)
- Reconnect the M34 No. 22 CAN junction connector.
*a Front view of wire harness connector
(to Clearance Warning ECU Assembly) - Disconnect the H46 clearance warning ECU assembly connector.
- Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection Condition Specified Condition H46-37 (CANH) - H46-38 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 54 to 69 Ω Result
Proceed to OK NG
Result:
OK
REPLACE CLEARANCE WARNING ECU ASSEMBLY
Refer to REMOVAL [11/2023 - ]
Result:
NG
REPAIR OR REPLACE CAN BUS WIRE (CLEARANCE WARNING ECU ASSEMBLY - NO. 22 CAN JUNCTION CONNECTOR)
- Reconnect the M34 No. 22 CAN junction connector.
- CHECK FOR SHORT IN CAN BUS WIRES (NO. 22 JUNCTION CONNECTOR)
- Disconnect the No. 22 CAN junction connector.
*a Front view of wire harness connector
(to No. 22 CAN Junction Connector)*b to Clearance Warning ECU Assembly CAN Wire *c to Blind Spot Monitor Sensor RH (A) CAN Main Wire *d to Blind Spot Monitor Sensor LH (B) CAN Main Wire - Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection Condition Specified Condition M34-3 (CANH) - M34-14 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher M34-2 (CA2P) - M34-13 (CA2N) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω M34-1 (CA2P) - M34-12 (CA2N) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Result
Result Proceed to OK A NG (to blind spot monitor sensor LH (B) CAN main wire) B NG (to blind spot monitor sensor RH (A) CAN main wire) C NG (to clearance warning ECU assembly CAN wire) D
Result:
A
REPLACE NO. 22 CAN JUNCTION CONNECTOR
Result:
C
See step 15
Result:
D
See step 16
Result:
B
See step 14
- Disconnect the No. 22 CAN junction connector.
- CHECK FOR SHORT IN CAN BUS WIRES (BLIND SPOT MONITOR SENSOR LH (B))
- Reconnect the M34 No. 22 CAN junction connector.
*a Front view of wire harness connector
(to Blind Spot Monitor Sensor LH (B)) - Disconnect the M43 blind spot monitor sensor LH (B) connector.
- Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection Condition Specified Condition M43-1 (CA2P) - M43-6 (CA2N) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Result
Proceed to OK NG
Result:
OK
REPLACE BLIND SPOT MONITOR SENSOR LH (B)
Refer to REMOVAL [11/2023 - ]
Result:
NG
REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (BLIND SPOT MONITOR SENSOR LH (B) - NO. 22 CAN JUNCTION CONNECTOR)
- Reconnect the M34 No. 22 CAN junction connector.
- CHECK FOR SHORT IN CAN BUS WIRES (BLIND SPOT MONITOR SENSOR RH (A))
- Reconnect the M34 No. 22 CAN junction connector.
*a Front view of wire harness connector
(to Blind Spot Monitor Sensor RH (A)) - Disconnect the M2 blind spot monitor sensor RH (A) connector.
- Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection Condition Specified Condition M2-1 (CA2P) - M2-6 (CA2N) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Result
Proceed to OK NG
Result:
OK
REPLACE BLIND SPOT MONITOR SENSOR RH (A)
Refer to REMOVAL [11/2023 - ]
Result:
NG
REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (BLIND SPOT MONITOR SENSOR RH (A) - NO. 22 CAN JUNCTION CONNECTOR)
- Reconnect the M34 No. 22 CAN junction connector.
- CHECK FOR SHORT IN CAN BUS WIRES (CLEARANCE WARNING ECU ASSEMBLY)
- Reconnect the M34 No. 22 CAN junction connector.
*a Front view of wire harness connector
(to Clearance Warning ECU Assembly) - Disconnect the H46 clearance warning ECU assembly connector.
- Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection Condition Specified Condition H46-37 (CANH) - H46-38 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 54 to 69 Ω Result
Proceed to OK NG
Result:
OK
REPLACE CLEARANCE WARNING ECU ASSEMBLY
Refer to REMOVAL [11/2023 - ]
Result:
NG
REPAIR OR REPLACE CAN BUS WIRE (CLEARANCE WARNING ECU ASSEMBLY - NO. 22 CAN JUNCTION CONNECTOR)
- Reconnect the M34 No. 22 CAN junction connector.
- CHECK FOR SHORT IN CAN BUS (BLIND SPOT MONITOR SENSOR LH (B) CONNECTION MAIN LINE)
- Disconnect the No. 22 CAN junction connector.
*a Front view of wire harness connector
(to No. 22 CAN Junction Connector)*1 DLC3 - Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection Condition Specified Condition M34-2 (CA2P) - Body ground Disconnect cable from negative (-) auxiliary battery terminal 200 Ω or higher M34-13 (CA2N) - Body ground Disconnect cable from negative (-) auxiliary battery terminal 200 Ω or higher M34-2 (CA2P) - H56-16 (BAT) Disconnect cable from negative (-) auxiliary battery terminal 6 kΩ or higher M34-13 (CA2N) - H56-16 (BAT) Disconnect cable from negative (-) auxiliary battery terminal 6 kΩ or higher HINT:
Check for short that was confirmed to be a malfunction by confirming symptoms.
Result
Proceed to OK NG
Result:
NG
See step 22
Result:
OK
See step 18
- Disconnect the No. 22 CAN junction connector.
- CHECK FOR SHORT IN CAN BUS (BLIND SPOT MONITOR SENSOR RH (A) CONNECTION MAIN LINE)
- Disconnect the No. 22 CAN junction connector.
*a Front view of wire harness connector
(to No. 22 CAN Junction Connector)*1 DLC3 - Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection Condition Specified Condition M34-1 (CA2P) - Body ground Disconnect cable from negative (-) auxiliary battery terminal 200 Ω or higher M34-12 (CA2N) - Body ground Disconnect cable from negative (-) auxiliary battery terminal 200 Ω or higher M34-1 (CA2P) - H56-16 (BAT) Disconnect cable from negative (-) auxiliary battery terminal 6 kΩ or higher M34-12 (CA2N) -H56-16 (BAT) Disconnect cable from negative (-) auxiliary battery terminal 6 kΩ or higher HINT:
Check for short that was confirmed to be a malfunction by confirming symptoms.
Result
Proceed to OK NG
Result:
NG
See step 21
Result:
OK
See step 19
- Disconnect the No. 22 CAN junction connector.
- CHECK FOR SHORT IN CAN BUS (CLEARANCE WARNING ECU ASSEMBLY CONNECTION BRANCH LINE)
- Reconnect the No. 22 CAN junction connector.
*a Front view of wire harness connector
(to No. 22 CAN Junction Connector)*1 DLC3 - Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection Condition Specified Condition M34-3 (CANH) - Body ground Disconnect cable from negative (-) auxiliary battery terminal 200 Ω or higher M34-14 (CANL) - Body ground Disconnect cable from negative (-) auxiliary battery terminal 200 Ω or higher M34-3 (CANH) - H56-16 (BAT) Disconnect cable from negative (-) auxiliary battery terminal 6 kΩ or higher M34-14 (CANL) - H56-16 (BAT) Disconnect cable from negative (-) auxiliary battery terminal 6 kΩ or higher HINT:
Check for short that was confirmed to be a malfunction by confirming symptoms.
Result
Proceed to OK NG
Result:
OK
REPLACE NO. 22 CAN JUNCTION CONNECTOR
Result:
NG
See step 20
- Reconnect the No. 22 CAN junction connector.
- CHECK FOR SHORT IN CAN BUS (CLEARANCE WARNING ECU ASSEMBLY)
- Reconnect the M34 No. 22 CAN junction connector.
*a Front view of wire harness connector
(to Clearance Warning ECU Assembly)*1 DLC3 - Disconnect the connector of the clearance warning ECU assembly.
- Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection Condition Specified Condition H46-37 (CANH) - Body ground Disconnect cable from negative (-) auxiliary battery terminal 200 Ω or higher H46-38 (CANL) - Body ground Disconnect cable from negative (-) auxiliary battery terminal 200 Ω or higher H46-37 (CANH) - H56-16 (BAT) Disconnect cable from negative (-) auxiliary battery terminal 6 kΩ or higher H46-38 (CANL) - H56-16 (BAT) Disconnect cable from negative (-) auxiliary battery terminal 6 kΩ or higher Result
Proceed to OK NG
Result:
OK
REPLACE CLEARANCE WARNING ECU ASSEMBLY
Refer to REMOVAL [11/2023 - ]
Result:
NG
REPAIR OR REPLACE CAN BUS BRANCH LINE OR CONNECTOR (CLEARANCE WARNING ECU ASSEMBLY - NO. 22 CAN JUNCTION CONNECTOR)
- Reconnect the M34 No. 22 CAN junction connector.
- CHECK FOR SHORT IN CAN BUS (BLIND SPOT MONITOR SENSOR RH (A))
- Reconnect the M34 No. 22 CAN junction connector.
*a Front view of wire harness connector
(to Blind Spot Monitor Sensor RH (A))*1 DLC3 - Disconnect the M2 blind spot monitor sensor RH (A).
- Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection Condition Specified Condition M2-1 (CA2P) - Body ground Disconnect cable from negative (-) auxiliary battery terminal 200 Ω or higher M2-6 (CA2N) - Body ground Disconnect cable from negative (-) auxiliary battery terminal 200 Ω or higher M2-1 (CA2P) - H56-16 (BAT) Disconnect cable from negative (-) auxiliary battery terminal 6 kΩ or higher M2-6 (CA2N) - H56-16 (BAT) Disconnect cable from negative (-) auxiliary battery terminal 6 kΩ or higher Result
Proceed to OK NG
Result:
OK
REPLACE BLIND SPOT MONITOR SENSOR RH (A)
Refer to REMOVAL [11/2023 - ]
Result:
NG
REPAIR OR REPLACE CAN BUS MAIN LINE OR CONNECTOR (BLIND SPOT MONITOR SENSOR RH (A) - NO. 22 CAN JUNCTION CONNECTOR)
- Reconnect the M34 No. 22 CAN junction connector.
- CHECK FOR SHORT IN CAN BUS (BLIND SPOT MONITOR SENSOR LH (B))
- Reconnect the M34 No. 22 CAN junction connector.
*a Front view of wire harness connector
(to Blind Spot Monitor Sensor LH (B))*1 DLC3 - Disconnect the connector of the blind spot monitor sensor LH (B).
- Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection Condition Specified Condition M43-1 (CA2P) - Body ground Disconnect cable from negative (-) auxiliary battery terminal 200 Ω or higher M43-6 (CA2N) - Body ground Disconnect cable from negative (-) auxiliary battery terminal 200 Ω or higher M43-1 (CA2P) - H56-16 (BAT) Disconnect cable from negative (-) auxiliary battery terminal 6 kΩ or higher M43-6 (CA2N) - H56-16 (BAT) Disconnect cable from negative (-) auxiliary battery terminal 6 kΩ or higher Result
Proceed to OK NG
Result:
OK
REPLACE BLIND SPOT MONITOR SENSOR LH (B)
Refer to REMOVAL [11/2023 - ]
Result:
NG
REPAIR OR REPLACE CAN BUS MAIN LINE OR CONNECTOR (BLIND SPOT MONITOR SENSOR LH (B) - NO. 22 CAN JUNCTION CONNECTOR)
- Reconnect the M34 No. 22 CAN junction connector.
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.