Changan Eado EV Motor System Fault Diagnosis and Disassembly Guide

Fault Background

The electric drive system of the Changan Eado EV uses a motor controller (IPU) to drive the motor output torque via vector control, relying on sequential switching of IGBT switching tubes to achieve forward rotation, reverse rotation, and regenerative braking. On the motor side, a temperature sensor (connector c-141169-1, signal positive/signal ground) and a resolver (connector c-6-1419166-1, excitation +/-, SIN+/-, COS+/-, pin current ≤1A) are fitted. Fault codes are concentrated in the P19xx family: over-temperature/over-voltage/under-voltage/overspeed/power module/resolver/stall/interlock, etc., nearly 30 codes. The troubleshooting for almost every code follows the routine of "clear codes and re-read → cool to room temperature and retest → replace controller or motor". Torque discipline during disassembly is clear (mount M10/M8, three-phase M8, junction box M6, cover M5), and internal assembly has another four levels: 20~26N·m, 9~11N·m, 4.8/6N·m, 5~7N·m. This article is compiled as a maintenance guide.

Working Principle and Connector Definitions

Control principle: ① The motor controller outputs torque via vector control; ② It controls the sequential switching of IGBT switching tubes to achieve motor forward rotation, reverse rotation, and regenerative braking.

Motor assembly interface: Three-phase power harness interface (U/V/W); temperature sensor connector c-141169-1 (signal positive/signal ground); resolver connector c-6-1419166-1—1 excitation +, 2 excitation -, 3 SIN+, 4 SIN-, 7 COS-, 8 COS+, each pin current not exceeding 1A.

Motor controller (IPU) structure: DC bus, harness mounting bolts (to housing) M6, high-voltage distribution, controller mounting holes M8, junction box mounting bolts M5, 14-pin/8-pin/4-pin low-voltage connectors, coolant hose ports, ground wire mounting holes, DC bus fixing bolts M8.

Torque Specification Quick Reference

Discipline: During disassembly and assembly, bolts must be tightened to the specified torque; the sealing ring is installed at the spigot of the motor rear end cover, and the sealing strip must be smooth and wrinkle-free after installation.

Over-Temperature Fault Family

Troubleshooting routine (using P1900/P190C as an example): Clear codes → power on again and re-read; if not reproduced, release the vehicle; if reproduced, wait until cooled to room temperature, then power on, clear codes, and re-read—if fault persists → check the motor temperature sensor connector pins (repair pins if repairable, otherwise replace the motor) → check the motor controller side (replace the motor controller). P1991 is handled separately: cool to room temperature → power on in ON mode, clear codes, and re-read; if still present, replace the motor controller.

Voltage and Power Module Fault Family

Resolver/Stall/Interlock/Communication Fault Family

• P1923 Motor resolver fault (external harness loop fault): Refer to P1918 troubleshooting; P1994 DC current sensor fault also refer to P1918; P1992 Motor temperature sensor fault refer to P1930;
• P1929 Motor stall fault: First check whether there is a condition of motor speed <60 rpm under high torque for >5s (check whether the parking brake or service brake is not released)—if so, rule out human-induced stall; if not, check the low-voltage connector/harness connection reliability → replace the motor controller;
• P191B/P191C Motor overspeed level 1/level 2: Cool to room temperature → clear codes and re-read → if reproduced, check the harness (repair the high-voltage harness if abnormal) → replace the motor;
• P1933 Three-phase input high-voltage interlock fault: Check the high-voltage interlock pins of the three-phase input harness of the motor controller; if no abnormality, replace the motor controller;
• P1931 IPU system fault: Power on, clear codes, re-read; if reproduced, check the low-voltage harness and communication between the controller and the vehicle control unit (replace the low-voltage harness/VCU/controller according to the diagnostic tree);
• P1935 131-frame CAN message (IPU131 CRC) checksum fault: Refer to U1293 troubleshooting;
• Reserved codes (noted as reserved in the manual; if reported, handle per technical support): P1928 Pre-charging fault, P1932 VMS ENABLE signal fault, P1937 Motor actual torque CRC error, P1993 High-voltage sensor fault.

Diagnostic Tools and General Checks

Tools: Diagnostic scan tool (to collect operating data during dynamic system operation); digital multimeter (to check characteristic parameters such as voltage, resistance, and current of the pure electric powertrain).

Transmission oil check: Check oil level with the vehicle level; check for oil leaks (if found, identify and repair the leak source); remove the level plug and check the oil level—oil flowing out of the level hole is normal. Transmission oil change: During maintenance, with the vehicle raised, check oil level and leaks, and replace per specifications.

Key Parameter Quick Reference

Safety Warnings

• This article is for technical reference. The electric drive system is a high-voltage component; disassembly and assembly must be performed by personnel trained on this vehicle's high-voltage system. Disconnect high voltage and verify voltage before working.
• The pin current of the resolver/temperature sensor connectors must not exceed 1A—do not force test with high current ranges.
• Checking the high-voltage interlock pins (three-phase input harness) is mandatory for P1933; never short-circuit the interlock loop.
• Before troubleshooting motor stall, confirm the parking brake/brake status to avoid disassembling the motor under load.

Maintenance Insights

The most notable feature of the P19xx code family is its "graded pairing": over-temperature, over-voltage, under-voltage, and overspeed all appear as level 1/level 2 pairs, and the troubleshooting sequence is fixed—first clear codes and re-read (to rule out history codes and intermittent faults), then cool to room temperature and retest (to rule out hot-state false positives), and only then touch hardware. Hardware replacement also has clear boundaries: harness issues are repaired on the harness, pin issues are repaired on the pins, temperature sensor/resolver faults require motor replacement (sensors are integrated at the motor end), and controller body faults require IPU replacement. Two on-site details worth remembering: P1920 discharge fault is often a "scapegoat code"—if it occurs alongside high-speed power-down, it is normal; only when it appears alone does it need investigation; P1929 stall requires ruling out human factors first (<60 rpm for 5 seconds under high torque is mostly due to the parking brake not released or brake drag), so don't disassemble the motor immediately. Torque memory also follows a pattern: external mounts use M10/M8 coarse threads, electrical connections use M6/M5 fine threads, internal assembly is covered by the 20~26 and 9~11 ranges, and the harness flange "tighten 4.8, standard 6" indicates a soft connection—don't overtighten.

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【This article is for reference only】