Mercedes-benz P1d687a Page

Measure voltage at BMS master connector – must be >11.5V during cranking.

Perform HV isolation test to rule out moisture ingress into battery pack (which can short bus lines). mercedes-benz p1d687a

| Cause | Probability | Mechanism | |-------|-------------|------------| | | 45% | Internal ASIC (e.g., Maxim MAX17853, ADI LTC6811) loses communication due to supply noise or latch-up | | Internal bus wiring harness fault | 25% | Broken or high-resistance connection on battery internal CAN/LIN (e.g., wire bond inside pack, corroded connector) | | BMS master internal fault | 15% | Failed transceiver or corrupted firmware | | Electromagnetic interference | 10% | External HV switching (e.g., DC-DC converter, compressor inverter) injecting noise onto internal bus – rare | | Software timing issue | 5% | CSC firmware timing drift after many wake/sleep cycles (fixed by update) | 6. Diagnostic Procedure (XENTRY) Step 1 – Verify DTC Scan all HV components. P1D687A may appear alongside P1D687B, P1D687C if multiple CSCs lost. Measure voltage at BMS master connector – must be >11