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SRS - Troubleshooting 52B-25 Code No.27 Driver’s seat belt pre-tensioner (squib) system Possible Cause This code is output when open circuit occurs in the SRS-ECU driver’s seat belt pre-tensioner (squib) circuit. However, SRS warning lamp goes out when a normal operation is resumed (diagnosis code is not cleared.) D Connector improper contact D Open in the driver’s seat pre-tensioner (squib) circuit D SRS-ECU inoperable <Check the driver’s seat belt pre-tensioner (squib)> Connect the dummy harness (MB991865) to the resistor harness (MB991866). D Disconnect the driver’s seat belt pre-tensioner connector D-28* 1 and D-26* 2 and insert the resistor harness (MB991866) behind the harness side connector. Caution Do not directly insert a probe or other devices at the front of the connector to avoid a possible decrease in the contact pressure. D Connect the negative (-) terminal of the battery D Check the diagnosis code again after erasing the memory. Is code No.27 output? YES NO Replace the driver’s seat belt pre-tensioner. Replace the SRS-ECU. Check the trouble symptoms. NG Check the harness between the driver’s seat belt pre-tensioner and the SRS-ECU, and repair if necessary. NG OK OK NG Correct Check connector: D-28 * 1 , D-26 * 2 , C-133 * 1 , C-112 * 2 , C-124 Driver’s seat belt pre-tensioner connector <Check the circuit between the SRS-ECU and the driver’s seat belt pretensioner> Measure at the SRS-ECU connector C-41, the driver’s seat belt pre-tensioner connector D-28* 1 and D-26 *2 . D Disconnect the SRS-ECU connector C-41 , the driver’s seat belt pre-tensioner connector D-28* 1 and D-26* 2 , and then measure at the harness side. D Continuity check between the following terminals D-28* 1 , D-26* 2 29 – 2 30 – 1 Caution Do not directly insert a probe or other devices at the front of the connector to avoid a possible decrease in the contact pressure. OK: Continuity (2Ω or less) Resistor harness (MB991866) Dummy resistor (MB991865) resistance (3Ω) Instrumental panel wiring harness Connector C-41 D-28* 1 , D-26* 2 connector NOTE *1: L.H. drive vehicles *2: R.H. drive vehicles |