Lexus NX: GSW Terminal Circuit Malfunction (B1243)
DESCRIPTION
If the collision door lock release function does not operate normally, or an open or short in the GSW input circuit of the main body ECU (multiplex network body ECU) is detected, DTC B1243 will be stored.
| DTC No. | Detection Item | DTC Detection Condition | Trouble Area |
|---|---|---|---|
| B1243 | GSW Terminal Circuit Malfunction | A malfunction occurs in the GSW input circuit of the main body ECU (multiplex network body ECU). |
|
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.
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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.
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-
If the main body ECU (multiplex network body ECU) is replaced, refer to the Smart Access System with Push-button Start (for Entry Function).
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- When DTC B1243 is output, the collision door lock release, shift-linked automatic door lock/unlock and speed-sensitive automatic door lock functions are prohibited.
-
After replacing the airbag ECU assembly, refer to initialization.
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PROCEDURE
| 1. | CLEAR DTC |
(a) Clear the DTCs.
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| 2. | CHECK FOR DTC |
(a) Recheck for DTCs.
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OK:
DTC B1243 is not output.
| OK | .gif) | USE SIMULATION METHOD TO CHECK |
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| 3. | CHECK MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) |
| (a) Disconnect the cable from the negative (-) auxiliary battery terminal. CAUTION: Wait at least 90 seconds after disconnecting the cable from the negative (-) auxiliary battery terminal to disable the SRS system. NOTICE: Turning the power switch on (IG) with the airbag ECU assembly connector disconnected causes other DTCs to be stored. Clear the DTCs after performing this inspection. |
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(b) Disconnect the airbag ECU assembly connector.
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(c) Connect the cable to the negative (-) auxiliary battery terminal.
(d) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
| Tester Connection | Switch Condition | Specified Condition |
|---|---|---|
| I58-18 (GSW) - Body ground | Power switch on (IG) | 2.8 to 4.2 V |
| OK | | REPLACE AIRBAG ECU ASSEMBLY |
|
| 4. | CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - AIRBAG ECU ASSEMBLY) |
(a) Disconnect the cable from the negative (-) auxiliary battery terminal.
CAUTION:
Wait at least 90 seconds after disconnecting the cable from the negative (-) auxiliary battery terminal to disable the SRS system.
(b) Disconnect the 4D instrument panel junction block assembly connector.
(c) Disconnect the I58 airbag ECU assembly connector.
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(d) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| 4D-46 - I58-18 (GSW) | Always | Below 1 Ω |
| 4D-46 or I58-18 (GSW) - Body ground | Always | 10 kΩ or higher |
| NG | | REPLACE INSTRUMENT PANEL WIRE |
|
| 5. | INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY |
(a) Remove the instrument panel junction block assembly.
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(b) Remove the main body ECU (multiplex network body ECU) from the instrument panel junction block assembly.
(c) Measure the resistance according to the value(s) in the table below.
| *a | Component without harness connected (Instrument Panel Junction Block Assembly) | - | - |
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| A-24 (GSW) - 4D-46 | Always | Below 1 Ω |
| OK | | REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) |
| NG | | REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY |
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