Lexus NX: Short in Selectable Force Limiter Squib RH Circuit (B1940-B1943)
DESCRIPTION
The selectable force limiter circuit consists of the airbag ECU assembly and front seat outer belt assembly RH.
This circuit instructs the SRS to deploy when deployment conditions are met.
These DTCs are stored when a malfunction is detected in the selectable force limiter circuit.
| DTC No. | Detection Item | DTC Detection Condition | Trouble Area |
|---|---|---|---|
| B1940 | Short in Selectable Force Limiter Squib RH Circuit | One of the following conditions is met:
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| B1941 | Open in Selectable Force Limiter Squib RH Circuit | One of the following conditions is met:
|
|
| B1942 | Short to GND in Selectable Force Limiter Squib RH Circuit | One of the following conditions is met:
|
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| B1943 | Short to B+ in Selectable Force Limiter Squib RH Circuit | One of the following conditions is met:
|
|
WIRING DIAGRAM
CAUTION / NOTICE / HINT
NOTICE:
-
After the power switch is turned off, there may be a waiting time before disconnecting the negative (-) auxiliary battery terminal.
Click here
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-
When disconnecting and reconnecting the auxiliary battery
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HINT:
When disconnecting and reconnecting the auxiliary battery, there is an automatic learning function that completes learning when the respective system is used.
Click here
-
After replacing the airbag assembly, refer to initialization.
Click here
HINT:
To perform the simulation method, enter check mode (signal check) with the Techstream (Click here ), and then wiggle each connector of the airbag system or drive the vehicle on various types of road (Click here ).
PROCEDURE
| 1. | CHECK FRONT SEAT OUTER BELT ASSEMBLY RH (SELECTABLE FORCE LIMITER) |
| (a) Turn the power switch off. |
|
(b) Disconnect the cable from the negative (-) auxiliary battery terminal, and wait for at least 90 seconds.
(c) Disconnect the connectors from the front seat outer belt assembly RH.
(d) Connect the white wire side of SST (resistance: 2.1 Ω) to connector C.
CAUTION:
Never connect the tester to the front seat outer belt assembly RH (selectable force limiter) for measurement, as this may lead to a serious injury due to airbag deployment.
NOTICE:
- Do not forcibly insert SST into the terminals of the connector when connecting SST.
- Insert SST straight into the terminals of the connector.
SST: 09843-18061
(e) Connect the cable to the negative (-) auxiliary battery terminal, and wait for at least 2 seconds.
(f) Turn the power switch on (IG), and wait for at least 60 seconds.
(g) Clear the DTCs.
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(h) Turn the power switch off.
(i) Turn the power switch on (IG), and wait for at least 60 seconds.
(j) Check for DTCs.
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HINT:
Codes other than DTC B1940, B1941, B1942 and B1943 may be output at this time, but they are not related to this check.
(k) Turn the power switch off.
(l) Disconnect the cable from the negative (-) auxiliary battery terminal, and wait for at least 90 seconds.
(m) Disconnect SST from connector C.
| DTC B1940, B1941, B1942 or B1943 is not output | .gif) | REPLACE FRONT SEAT OUTER BELT ASSEMBLY RH |
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| 2. | CHECK CONNECTORS |
(a) Disconnect the connectors from the airbag ECU assembly.
| (b) Check that the connectors (on the airbag ECU assembly side and front seat outer belt assembly RH side) are not damaged. OK: The lock button is not disengaged, and the claw of the lock is not deformed or damaged. |
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| NG | | REPLACE FLOOR WIRE |
|
| 3. | CHECK FRONT SEAT OUTER BELT ASSEMBLY RH (SELECTABLE FORCE LIMITER) CIRCUIT |
| (a) Connect the cable to the negative (-) auxiliary battery terminal, and wait for at least 2 seconds. |
|
(b) Turn the power switch on (IG).
(c) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
| Tester Connection | Switch Condition | Specified Condition |
|---|---|---|
| P40-2 (SR+) - Body ground | Power switch on (IG) | Below 1 V |
| P40-1 (SR-) - Body ground | Power switch on (IG) | Below 1 V |
(d) Turn the power switch off.
(e) Disconnect the cable from the negative (-) auxiliary battery terminal, and wait for at least 90 seconds.
(f) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| P40-2 (SR+) - P40-1 (SR-) | Always | Below 1 Ω |
(g) Release the activation prevention mechanism built into connector B.
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(h) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| P40-2 (SR+) - P40-1 (SR-) | Always | 1 MΩ or higher |
(i) Restore the released activation prevention mechanism of connector B to its original condition.
(j) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| P40-2 (SR+) - Body ground | Always | 1 MΩ or higher |
| P40-1 (SR-) - Body ground | Always | 1 MΩ or higher |
| NG | | REPLACE FLOOR WIRE |
|
| 4. | CHECK DTC |
| (a) Connect the connectors to the front seat outer belt assembly RH and airbag ECU assembly. |
|
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(b) Connect the cable to the negative (-) auxiliary battery terminal, and wait for at least 2 seconds.
(c) Turn the power switch on (IG), and wait for at least 60 seconds.
(d) Clear the DTCs.
Click here
(e) Turn the power switch off.
(f) Turn the power switch on (IG), and wait for at least 60 seconds.
(g) Check for DTCs.
Click here
HINT:
Codes other than B1940, B1941, B1942 and B1943 may be output at this time, but they are not related to this check.
| DTC B1940, B1941, B1942 or B1943 is not output | | USE SIMULATION METHOD TO CHECK |
| DTC B1940, B1941, B1942 or B1943 is output | | REPLACE AIRBAG ECU ASSEMBLY |
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