Lexus NX: Back Door Closer Switch Malfunction (B2251)
DESCRIPTION
The multiplex network door ECU receives signals from the latch switch, initial switch, pawl switch and back door courtesy switch, which are built into the back door lock assembly. Based on these switch signals, the latch position of the back door lock assembly is determined.
| DTC No. | Detection Item | DTC Detection Condition | Trouble Area |
|---|---|---|---|
| B2251 | Back Door Closer Switch Malfunction | While the back door closer is operating, a malfunction is detected in position information from the back door courtesy switch within a specified amount of time. |
|
WIRING DIAGRAM
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CAUTION / NOTICE / HINT
NOTICE:
- Inspect the fuses for circuits related to this system before performing the following procedure.
-
If the replacement, removal and installation of the multiplex network door ECU or disconnection of the connectors of the multiplex network door ECU has been performed, initialize the power back door system.
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- Recognition code registration is necessary when replacing the main body ECU (multiplex network body ECU).
-
If the main body ECU (multiplex network body ECU) is replaced, refer to Registration.
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PROCEDURE
| 1. | READ VALUE USING TECHSTREAM |
(a) Read the Data List according to the display on the Techstream.
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| Tester Display | Measurement Item | Range | Normal Condition | Diagnostic Note |
|---|---|---|---|---|
| Courtesy SW | Back door courtesy light switch signal | ON or OFF | ON: Back door open OFF: Back door closed | Refer to "CONSTRUCTION AND OPERATION"* |
*: Refer to "CONSTRUCTION AND OPERATION"
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| Tester Display |
|---|
| Courtesy SW |
OK:
The display is as specified in the normal condition column.
| OK | .gif) | REPLACE MULTIPLEX NETWORK DOOR ECU |
|
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| 2. | INSPECT BACK DOOR LOCK ASSEMBLY |
(a) Remove the back door lock assembly.
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(b) Inspect the back door lock assembly.
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| NG | | REPLACE BACK DOOR LOCK ASSEMBLY |
|
| 3. | CHECK HARNESS AND CONNECTOR (BACK DOOR LOCK ASSEMBLY - MULTIPLEX NETWORK DOOR ECU AND BODY GROUND) |
(a) Disconnect the 4A instrument panel junction block assembly connector.
(b) Disconnect the Y12 back door lock assembly connector.
(c) Disconnect the Y26 multiplex network door ECU connector.
(d) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| Y12-8 (CTY) - Y26-11 (FUL) | Always | Below 1 Ω |
| Y12-7 (E) - Body ground | Always | Below 1 Ω |
| Y12-8 (CTY) or Y26-11 (FUL) - Body ground | Always | 10 kΩ or higher |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
| 4. | CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - MULTIPLEX NETWORK DOOR ECU) |
(a) Disconnect the 4A instrument panel junction block assembly connector.
(b) Disconnect the Y26 multiplex network door ECU connector.
(c) Disconnect the Y12 back door lock assembly connector.
(d) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| 4A-21 - Y26-11 (FUL) | Always | Below 1 Ω |
| 4A-21 or Y26-11 (FUL) - Body ground | Always | 10 kΩ or higher |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
| 5. | INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY |
| (a) Remove the instrument panel junction block assembly. Click here |
|
(b) Remove the main body ECU (multiplex network body ECU) from the instrument panel junction block assembly.
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(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| A-4 (BCTY) - 4A-21 | Always | Below 1 Ω |
| A-4 (BCTY) or 4A-21 - Body ground | Always | 10 kΩ or higher |
| NG | | REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY |
|
| 6. | READ VALUE USING TECHSTREAM |
(a) Disconnect the Y26 multiplex network door ECU connector.
(b) Read the Data List according to the display on the Techstream.
Click here
| Tester Display | Measurement Item | Range | Normal Condition | Diagnostic Note |
|---|---|---|---|---|
| Back Door Courtesy SW | Back door courtesy switch signal | ON or OFF | ON: Back door open OFF: Back door closed | - |
| Tester Display |
|---|
| Back Door Courtesy SW |
OK:
The display is as specified in the normal condition column.
| OK | | REPLACE MULTIPLEX NETWORK DOOR ECU |
| NG | | REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) |
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