AITO M5 Front Motor Controller Precision Test Guide

Fault Background

The AITO M5's electric drive system precision test (HW165 front drive) divides motor controller-related DTCs into ten test groups A~J, each following a unified "pre-check → clear codes and retest → fuse/relay → point-to-point power circuit measurement → replace part" procedure. Core measurement points: VCU connector CC50/CC51 (power lines M1/G4, always-on lines L1/M2/M3, enable line L2, CAN lines B1≈2.3V/B2≈2.7V), front motor controller connector BC14 (pins 1/10/12 battery voltage, pins 2/11 ground), front motor oil pump connector BC05 (pin 1 to ground battery voltage, continuity with BC14-17 <1Ω), fast charge CC1-PE resistance 1000Ω. The code families cover CAN BusOff, VCU communication, DC voltage sensor, cooling circuit, oil pump, etc. This article is compiled as a maintenance guide.

Test Framework and Pre-checks

Unified procedure: ①Pre-check (whether the corresponding connector is normal + whether the software version is latest + status of related components) → ②Connect diagnostic scan tool, clear DTCs, then re-read whether DTCs still exist (if not reproduced = intermittent fault) → ③Check fuses and relays (replace with new same capacity) → ④Measure power circuit point-to-point voltage/resistance according to group → ⑤Repair fault point or replace part, test system operation normal.

Test A: U007788 CAN BusOff / U029387 VCU Communication Abnormal

• A1: Check whether battery voltage, VCU connector, and software version are normal;
• A2: Clear codes with diagnostic scan tool → Do DTCs still exist after re-read?
• A3: Fuses and relays → Replace with new same capacity and test;
• A4 Power lines: Power on → Disconnect VCU connector CC50 → Measure whether terminals M1 and G4 have battery voltage — if abnormal, repair open or short circuit in VCU power circuit and main relay control lines LF10C (RD), VUAG4 (GN);
• A5 Always-on lines: Disconnect VCU connector CC51 → Measure whether terminals L1, M2, M3 have battery voltage — if abnormal, repair open or short circuit in VCU always-on circuit LF33C (GN-BK), LF33A (GN-BK);
• A6 Enable line: Measure whether terminal L2 of CC51 has battery voltage — if abnormal, repair VCU enable power circuit IF23 (GN-YE);
• A7 Ground: Measure terminals L3, L4, M4 of CC51 to ground;
• A8 CAN lines: Measure terminal B1 of CC51 approximately 2.3V, terminal B2 approximately 2.7V (CAN_H/CAN_L recessive levels).

Test B: DC Voltage Sensor Code Family

P3B0B96 DC voltage sensor fault / P3B0C96 DC voltage sensor warning (and P3B0000/P3B0519/P3B0619 family): Check motor connector and software version → Clear codes and read DTCs → Check whether terminals 1, 10, 12 of front motor controller BC14 wiring harness connector have battery voltage, and terminals 2, 11 (ground side) → If abnormal, repair circuit or replace part according to results.

Test C/I: Fast Charge CC1-PE Resistance

P3B0117/P3B0216 (Group C) and P3B2917/P3B2A16/P3B2C0D (Group I): Check whether the fast charge socket assembly and on-board charger connector are normal → Clear codes and retest → Measure whether the resistance between CC1 and PE is 1000Ω — if abnormal, check the corresponding circuit of the fast charge socket/charger.

Test D: Cooling Circuit Code Family

P3B1698/P3B1C4B/P3B2498/P3B2698: Check whether the drive motor water pump circuit is normal → Check whether the four-way control valve assembly circuit is normal → Clear codes and retest → Check whether the four-way control valve assembly is blocked — repair or replace according to inspection results.

Tests E~H: Controller Power and Body Code Families

• Group E B111717/B111716, Group F P3B0F96/P3B1096/P3B1196/P3B1296/P3B1396/P3B1417/P3B1516, Group G P3B1796/P3B1847/P3B1996/P3B1F96, Group H P3B2096/P3B2196/P3B2300/P3B3662/P3B3762/P0A0A001: All follow the "check motor connector + software version → clear codes and retest → measure battery voltage on terminals 1/10/12 of BC14 connector, ground on terminals 2/11" procedure, repair circuit or replace motor controller according to results.

Test J: Oil Pump and Communication Code Family

P3B2D00/P3B2E00/P3B2F00/P3B3400/P3B3500/U010987: Check battery voltage, front drive motor oil pump connector, front drive motor connector → Clear codes and retest → Check whether terminal 1 of front motor oil pump wiring harness connector BC05 to ground has battery voltage → Check terminal 3 of BC05 to ground → Check whether the resistance between terminal 17 of motor controller connector BC14 and terminal 2 of oil pump connector BC05 is <1Ω — repair or replace part according to results.

Key Parameter Quick Reference

Safety Warnings

• This article is for technical reference. The electric drive system is a high-voltage component; precision testing must be performed by technicians who have received high-voltage training and authorization for this vehicle model. Follow high-voltage discipline when measuring high-voltage-related terminals.
• Confirm the vehicle is in power-down state before disconnecting connectors for measurement; battery voltage measurement is on the low-voltage side; high-voltage side terminals are strictly prohibited from being measured while energized.
• Replacement fuses must use the same capacity specification; after replacing relays, system operation must be retested.

Maintenance Insights

The most valuable part of this precision test is the "point-to-point measurement table" — each code family A~J converges the fault to connector terminal-level voltage/resistance criteria: VCU's power (M1/G4), always-on (L1/M2/M3), enable (L2), ground (L3/L4/M4), CAN (B1/B2 at 2.3V/2.7V recessive levels) — five lines measured completely at once; motor controller BC14's 1/10/12 power + 2/11 ground is the common endpoint for four code families E~H; oil pump BC05 and BC14-17 <1Ω continuity is the decisive line for oil pump communication. Three rules worth remembering: Each group has "clear codes and retest" first — if not reproduced, it's an intermittent fault, don't rush to disassemble; CAN lines have specific voltage values (B1≈2.3V/B2≈2.7V), which are the standard recessive levels for CAN_H/CAN_L, deviation indicates bus issue; fast charge CC1-PE fixed at 1000Ω — this is the standard resistance of the national standard CC circuit, directly testing whether "charging gun recognition" is normal. Finally, process discipline: fuses/relays are always before connector measurements — high-current protection devices are the cheapest fault points, eliminate them first before measuring.

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【This article is for reference only】