AITO M5 Rear Motor Controller Precision Test Guide

Fault Background

The AITO M5's rear motor controller precision test (HW200) splits the DTC families into nine groups A~I, sharing the same framework as the front drive (HW165)—pre-checks → clear codes and retest → fuses/relays → connector point-to-point measurements → component replacement—but the DTC families and connectors are completely different: the rear motor controller uses the CC66 wiring harness connector (terminals 10 and 11), the rear motor oil pump uses the CC67 connector (terminals 1, 3, and 2); fuse details: front compartment electrical box LF10 (10A)/LF33 (10A) + LRELAY2 VCU main relay + cabin electrical box IF23 (10A). The DTC families cover overspeed, overcurrent, phase loss, active discharge, IGBT over-temperature, resolver, driver chip, SBC, ADC, self-test failure, and 60+ other codes. This article is organized as a service guide.

Test Framework and Fuse Details

Unified procedure: ①Pre-checks (connectors/software version/battery voltage) → ②Clear codes with diagnostic scan tool → re-read DTC still present? If not reproducible = intermittent fault → ③Replace fuses and relays with same rating → ④Connector point-to-point measurements → ⑤Repair fault point or replace component, verify system operates normally.

Fuses and relays (A3): Front compartment electrical box fuses LF10 (10A), LF33 (10A) and LRELAY2 VCU main relay; cabin electrical box fuse IF23 (10A).

Test A: VCU Communication and Five-Wire Measurement

U029387 VCU communication anomaly / U007788 CAN BusOff: Check battery voltage, VCU connector, software version → clear codes and retest → fuses/relays → A4: Power on, disconnect VCU connector CC50, measure terminals M1 and G4 for battery voltage (if abnormal, repair VCU power circuit and main relay control line LF10C (RD), VUAG4 (GN)) → A5: Disconnect CC51, measure L1/M2/M3 (constant power LF33C/LF33A) → A6: Measure L2 (enable IF23) → A7: Measure L3/L4/M4 to ground → A8: Measure B1 approx. 2.3V / B2 approx. 2.7V (CAN).

Test B: Motor Operating State DTC Family

P3B4000 Motor overspeed / P3B4519 AC RMS overcurrent / P3B4619 AC instantaneous hardware overcurrent / P3B4700 Output imbalance / P3B4800 Output phase loss / P3B6200 Active discharge fault / P3B6700 Forward rotation over-limit derating / P3B6800 Reverse rotation over-limit derating / P3B7662 Torque verification error / P3B7762 Torque verification fault: Check motor connector and software version → clear codes and retest → Disconnect rear motor controller CC66 wiring harness connector, measure terminals 10 and 11 (power/ground point-to-point) → repair or replace component based on results.

Test C/D: Bus Voltage and Temperature DTC Families

• Group C P3B4117 DC software overvoltage / P3B4216 DC software undervoltage / P3B6917 Bus overvoltage derating / P3B6C00 SOA derating: Check on-board charger connector → clear codes and retest → troubleshoot corresponding circuits;
• Group D P3B5698 IGBT over-temperature / P3B6498 Motor over-temperature derating / P3B5C4B Motor over-temperature / P3B6698 IGBT over-temperature derating: Check motor connector and software version → clear codes and retest → troubleshoot cooling circuit and temperature signals.

Test E/F: Power Supply and Sensor DTC Families

• Group E P3B4317 Low-voltage power supply overvoltage / P3B4416 Low-voltage power supply undervoltage / P3B7831 Ignition signal loss fault / P3B4982 Ignition signal loss fault: Check motor connector and software version → clear codes and retest → measure CC66 connector terminals 10/11;
• Group F P3B4A17 DC instantaneous overvoltage / P3B4B96 DC voltage sensor fault / P3B4C96 DC voltage sensor warning / P3B4D96 AC current sensor fault / P3B4E96 Drive power supply fault / P3B4F96 Backup power supply fault / P3B6A16 DC voltage sensor fault: Same procedure as above, replace component based on results.

Test G/H: Driver Stage and Board-Level DTC Families

• Group G P3B5096 5V power supply fault / P3B5196 High-voltage auxiliary supply fault / P3B5296 High-side driver fault / P3B5396 Low-side driver fault / P3B5417 Driver chip overvoltage / P3B5516 Driver chip undervoltage / P3B5796 Driver chip fault / P3B5847 SBC fault / P3B5996 Resolver fault / P3B5A96 IGBT temperature sensor anomaly / P3B5B96 Motor temperature detection fault: Check motor connector and software version → clear codes and retest → measure CC66 connector terminals 10/11 → repair or replace motor controller based on results;
• Group H P3B5D96 Motor temperature detection anomaly / P3B5E4B Driver board over-temperature / P3B5F96 Driver board temperature detection fault / P3B6096 External ADC chip fault / P3B6196 Internal communication fault / P3B6300 Self-test failure / P3B6598 Driver board over-temperature derating / P3B6B00 MCU inverse-time derating: Same procedure as above.

Test I: Rear Motor Oil Pump DTC Family

P3B6D00 Motor temperature detection anomaly / P3B6E00 Driver board over-temperature / P3B6F00 Driver board temperature detection fault / P3B7000 External ADC chip fault / P3B7100 Internal communication fault / P3B7200 Self-test failure / P3B7300 Driver board over-temperature derating / P3B7400/P3B7500 MCU inverse-time derating / U010987: Check motor oil pump connector → clear codes and retest → Disconnect rear motor oil pump CC67 wiring harness connector, measure terminal 1 (battery voltage to ground) → measure terminal 3 to ground → Disconnect CC67 and rear motor controller CC66 connectors, measure resistance between terminal 2 of CC67 and terminal 3 of CC66 (continuity to determine open circuit) → repair or replace component based on results.

Key Parameter Quick Reference

Safety Warnings

• This article is for technical reference. The rear motor controller is a high-voltage component; precision testing must be performed by technicians who have received high-voltage training for this vehicle model and are authorized. Never measure high-voltage terminals while energized.
• Before disconnecting connectors for measurement, confirm the vehicle is in the power-down state; replace fuses only with the same rating and specification.
• Active discharge fault (P3B6200) and self-test failure (P3B6300/P3B7200) point to internal controller issues; follow the procedure to replace the component and retest system operation.

Repair Insights

The rear drive HW200 DTC families are more complete than the front drive, exposing the layered architecture of the motor controller entirely in the codes: operation layer (overspeed/overcurrent/phase loss/torque verification Group B), bus layer (software overvoltage/undervoltage/SOA derating Group C), sensor layer (DC/AC current/temperature sensors Group F), driver layer (high/low-side drivers, driver chip overvoltage/undervoltage, SBC Group G), board-level layer (ADC/internal communication/self-test failure Group H)—from the code name you can determine which layer of the controller architecture the fault is in; driver layer and board-level layer codes basically converge to "replace the motor controller." On the measurement side, remember three points: terminals 10/11 of CC66 are the rear drive controller's "power + ground" point-to-point (corresponding to front drive BC14 terminals 1/10/12+2/11); CC67 oil pump connector three-terminal three-step measurement (terminal 1 voltage → terminal 3 to ground → terminal 2 ↔ CC66-3 continuity); fuse trio LF10/LF33/IF23 + LRELAY2 main relay—for CAN BusOff and VCU communication anomalies, check these three first before measuring wires. Finally, follow the front drive discipline: clear codes and retest first; do not disassemble components for intermittent faults.

---

【This article is for reference only】