Dongfeng Fengxing S50EV Vehicle Control Module (VCM) Fault Diagnosis and Removal/Installation Guide

Fault Background

The Dongfeng Fengxing S50EV (1468 manual) Vehicle Control Module (VCM) is the core of vehicle control, mounted on the left side of the instrument panel crossmember in the cabin, secured to the front bulkhead welded bracket with 3 Q32006 hex flange nuts. Maintenance discipline is strict: professionally trained technicians + OEM parts only + VCM is non-serviceable; before diagnosis, rule out other system faults first (motor over-temperature, battery pack over-temperature, high-voltage interlock, loose wiring harness connectors). Key criteria: VCM operating voltage 8~18V (12V battery standard 9.3~16.8V), dual fuses (constant power supply 1/2 each 15A), 4 ground points, CAN-H/CAN-L node-to-node resistance 60Ω, node-to-VCM wire resistance <5Ω. This article is organized as a diagnostic guide following: "Initial Inspection → Power Supply/CAN → Interlock/Drive → Sensors → Removal/Installation and EOL Configuration".

Initial Inspection and Power Supply Group

Initial Inspection: ①Both fuses (constant power supply 1/2 each 15A) not blown and correct type; ②12V battery voltage and terminal corrosion/looseness (operating range 8~18V); ③VCM ground wire ground point loose, ground point location changed; ④Ground wire sealing—prevent water/moisture from wicking (capillary/siphon effect) along wire harness holes into connectors causing functional failure; ⑤Wiring harness connectors connection, pinching/cutting; ⑥Wiring harness routing away from high-voltage or high-current devices (high-voltage components/motor/OBC/battery pack)—inductive noise interference with circuits.

P1E0000/P1E0010/P1E0100 VCM Power Supply Fault: Measure 12V battery voltage (standard 9.3~16.8V, charge if necessary) → Check VCM's 4 ground points → Check DC-DC operation → Turn on all high-power loads and measure power supply (high-load supply insufficiency) → Measure voltage fluctuation when starting/switching loads (potential load fault).

No DTC Fault: When MCU severe fault or BMS severe fault, VCM cannot energize high-voltage/actively de-energizes high-voltage—if no DTC, check these two systems and wiring harness connectors first.

CAN and Node Group

• U007300/U007400 CAN Bus Fault: 12V voltage → CAN wiring harness inspection → Replace VCM assembly;
• Bus Node Group (U010300/U011000/U011100/U120000/U012100/U015500/U015600/U016400/U014000/U014001/U029800/U019B00): ①Turn off power switch, measure resistance from each node to VCM on CAN-H, CAN-L (standard <5Ω); ②Measure resistance between CAN-H and CAN-L at each node connector (keep connector plugged) standard 60Ω; ③Check node power supply; ④Read each node's DTCs and inspect accordingly.

Interlock and Relay Drive Group

P1E0300 High-Voltage Interlock Detection Abnormal: Interlock loop 1 (motor controller, motor, high-voltage distribution box, air conditioning compressor, DC/DC, passenger compartment heater loop high-voltage connectors), interlock loop 2 (OBC, battery pack loop high-voltage connectors) loose/broken/harness damaged → Check controller-side low-voltage connectors of both loops → Battery pack MSD → Re-plug VCM connector → Replace VCM.

B301020 Main Positive and Main Negative Relays Simultaneously Stuck: Replace main positive and main negative relays + check MCU bus voltage.

12 Drive Fault Group (B301010 Main Positive Drive/B301030 Main Negative Drive/B302F10 E-STOP Drive/B302B20 BMS Wake-up Drive/B301110 Precharge Drive/B301210 Fast Charge Positive Drive/B301310 Heater Drive/B301410 Charge Gun Lock Coil Drive/B301420 Charge Gun Unlock Coil Drive/B301510 Reverse Relay Drive/B301610 M-C Relay Drive/B303710 Vacuum Pump Drive): Load (relay, fan, etc.) damaged/not installed → Replace VCM → Drive end to load harness open/short circuit, three-step troubleshooting.

Sensor and Actuator Group

• P1E0600/0700/P1E1F00/P1E1D00 Accelerator pedal, vacuum pressure, A/C condenser pressure sensor power supply voltage abnormal—Check VCM 5V power supply circuit and harness open/short; if still unresolved, replace VCM or sensor;
• P1E0800/0900/P1E1E00/P1E1E10/P1E2000/P1E2010/P1E2B00 Accelerator pedal 1/2 opening, A/C refrigerant pressure, battery pack outlet/inlet temperature, vacuum pressure, atmospheric pressure sensor input signal out of range—Check harness open/short → Replace sensor;
• P1E1A00/P1E1B00 Accelerator pedal 1 and 2 opening difference too large/simultaneous fault—Pedal 1 or 2 unstable/damaged;
• P1E1C00 Brake pedal fault (switch circuit open/short/incorrect installation/damaged);
• P1E0400 High-Voltage Energization Precharge Fault: Main positive/negative precharge relay, precharge resistor, wiring harness, MCU/BMS bus voltage feedback abnormal—Check VCM drive circuit harness short/loose connection → Check BMS/MCU bus voltage feedback → Return battery pack to factory for replacement;
• P1E2100~P1E2800 Water Pump Group: Drive system water pump/battery pack water pump idling, overcurrent, over-temperature, low speed each four codes—Check water pump, replace if necessary;
• P1E2C00 Charge Port Socket Temperature Too High: Different brand charging gun and socket mismatch, charging gun/socket dust accumulation causing increased resistance, socket temperature sensor fault—Replace gun/socket, clean dust, replace sensor;
• P1E2020 Cruise Switch Signal Error (pressed by object/circuit damaged); P1E2810/P1E2900 Vacuum System Slow Leak/Fast Leak (replace vacuum pump); P1E2A00 Collision Protection (clear codes; replace airbag ECU); B350614/U254183/U254187/B350771/B350B14/B350814/B350914/B350A14 SPORT button stuck/GSM communication/P gear motor overvoltage/overcurrent/drive timeout/position feedback/lock solenoid/Hall/plunger stuck—Check gear selector controller wiring → Replace gear selector mechanism.

Intermittent Fault Three Simulation Methods: Vibration cause → Gently wiggle VCM connector and related sensors (replace if harness broken); Temperature cause → Use heat gun to heat suspected parts, cold spray to check cold solder joints; Electrical load cause → Turn on all electrical switches (headlights, wipers, etc.) for high-load operation. Intermittent faults gradually evolve into reproducible faults and do not disappear on their own.

Removal/Installation and EOL Configuration

Removal: Remove lower left trim panel (per "Instrument Panel Assembly Adjustment Technical Conditions") → Remove 3 hex flange nuts → Unplug 2 connectors in sequence → Remove VCM. Installation: Place into mounting area, secure with 3 Q32006 hex flange nuts on bracket.

After replacing VCM, EOL configuration is mandatory (battery heater is optional): Diagnostic scan tool → "China"→"Dongfeng Fengxing (Special)"→ S50EV EV → VCM → End-of-Line Configuration → Battery Cooling Device Configuration + Battery Thermal Relay Configuration (6 steps each, 12 steps total). Note: Both configurations must be either "Yes" or "No"—if only one is set to "No", the vehicle still treats it as having the battery pack heater installed, affecting vehicle functions.

Safety Warnings

• This article is for technical reference. The VCM is the core of vehicle control; it must be serviced by professionally trained technicians per OEM specifications, OEM parts only, VCM is non-serviceable.
• Disconnect the power switch before unplugging VCM wiring; keep connectors dry and clean to prevent foreign objects; install in horizontal and vertical alignment.
• Before diagnosis, rule out upstream faults such as motor over-temperature/battery pack over-temperature/high-voltage interlock/loose harness connectors; high-voltage interlock inspection involves high-voltage connectors, disconnect high-voltage first to confirm safety.
• After replacing VCM, complete both EOL configurations for battery cooling device and battery thermal relay (both Yes or both No).

Maintenance Insights

The two most valuable actions from the S50EV VCM manual: "Rule out upstream faults before diagnosis"—the VCM is the "executor" of high-voltage shutdown without DTCs, not the "culprit"; when MCU/BMS have severe faults, VCM actively de-energizing high-voltage is a protective action, don't suspect VCM first; "Intermittent Fault Three Simulation Methods"—wiggle connectors, heat gun/cold spray for temperature, full electrical load—three tricks to force the fault to appear, saving time over repeated road tests. For CAN criteria, remember two numbers: 60Ω between nodes (measured with connectors plugged, which is the parallel value of two 120Ω terminating resistors) and <5Ω from node to VCM—the former verifies bus topology, the latter verifies wiring. Interlock diagnosis is a two-loop checklist: Loop 1 covers motor controller/motor/high-voltage distribution box/compressor/DCDC/heater, Loop 2 covers OBC/battery pack—check connectors point by point per the list, don't miss the passenger compartment heater as an obscure node. Finally, the EOL configuration pitfall: Battery cooling device and battery thermal relay must both be "Yes" or both "No"—if only one is set to No, the vehicle still treats it as having the heater installed—this is the most easily missed finishing step after replacing VCM.

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【This article is for reference only】