Technical Service Bulletin LI54.10-P-080004 — 2023 MERCEDES-BENZ EQB 300 4MATIC

Complaint • Vehicle cannot be started • Warning in the instrument cluster related to High-voltage on board electrical system • The following fault codes related to interlock can be found in the High Voltage Control units : • PTCU (N127) : P154700 - There is a warning due to a detected fault in the interlock circuit. • BMS (N82/9) : P0A0B00 - The interlock circuit of the high-voltage on-board electrical system has a malfunction. P0A0D00 - The interlock circuit of the high-voltage on-board electrical system has a short circuit to positive. • DCB (N116/5): P0A0A00 - The interlock circuit of the high-voltage on-board electrical system has an electrical fault. P0A0B00 - The interlock circuit of the high-voltage on-board electrical system has a malfunction. P0A0C00 - The interlock circuit of the high-voltage on-board electrical system has a short circuit to ground. • OBL (N83/11) : P0A0B00 - The interlock circuit of the high-voltage on-board electrical system has a malfunction. P0A0C00 - The interlock circuit of the high-voltage on-board electrical system has a short circuit to ground. Cause • Oxidation in interlock circuit pins of the low voltage connectors in the components • Twisted harness • Harness scratching with the body • Wiring harness chafed/cut at the ECUs • Broken interlock connector • Improperly connected HV connectors • Interlock pins on HV components are bent or deformed Important Note : • In case of interlock failures, the High-voltage component is less likely to cause the issue. Remedy Remedy 1: Interlock loop resistance measurement (Refer attachment "243 Interlock Resistance Measurements.pdf") Remedy 2: Additional check points for interlock issues