AITO M5 VCU Precision Test Guide

Fault Background

The VCU precision test for the AITO M5 covers approximately 57 test groups from A to BE, serving as a comprehensive vehicle diagnostic outline from the VCU perspective: high-voltage interlock family (P0A0A00, three wiring harnesses checked segment by segment), brake and chassis family (PC14↔FCR06-38 continuity), communication loss family (U-type 87/86 pairs—communication loss + Checksum/Counter, covering GCU/BMS/OBC/DCDC/MCUF/MCUR/GSM/EPB/CCU/PTC/IC/BCM/iBooster/IVI), pedal collision self-check family, thermal management family (expansion valve/four-way valve/three-way valve/temperature sensors/coolant level/four water pumps), motor family (stall/overtemperature/overcurrent/bus overvoltage/IGBT bridge). The unified approach remains the same: pre-checks → clear codes and retest → circuit point-to-point checks → component replacement. This article is organized as a service guide.

Test Framework

Unified approach: ① Pre-checks (connectors, battery and traction battery charge, etc., test conditions) → ② Clear DTCs with diagnostic scan tool → Re-power and read DTCs; if not reproduced = intermittent fault → ③ Perform circuit point-to-point checks by group (resistance/voltage/continuity) → ④ Repair fault point or replace corresponding component, then verify system operation.

High-Voltage Interlock Family (Test A)

P0A0A00 High-voltage interlock fault: Pre-check connectors of battery pack front high-voltage harness assembly, PTC-compressor high-voltage harness assembly, generator three-phase high-voltage harness assembly for looseness → Clear codes and retest → With vehicle powered down, disconnect connectors one by one and check high-voltage interlock signal for short to ground / short to power / open circuit—if abnormal, replace the corresponding high-voltage harness assembly → If all normal, check other modules and circuits for fault point repair.

Brake and Chassis Family (Tests B~E)

• Group B C007501 Brake pedal fault / C05CC01 Brake pressure sensor fault / C002103 Brake pedal invalid fault: Check brake pedal connector → Clear codes and retest → Disconnect brake pedal connector PC14 and ESC connector FCR06, measure continuity between terminal 2 of PC14 and terminal 38 of FCR06—if abnormal, replace brake pedal (refer to pedal bracket assembly);
• Group C C041601 EBD fault / C056301 ABS fault / C041602 ABS vehicle speed invalid / C041603 ESC and vehicle speed consistency fault: Diagnose along EBD/ABS/ESC vehicle speed signal path;
• Groups D~E: ACU/ESC related codes (U015187 ACU communication loss, U012287 ESC communication loss, etc.) follow the communication family approach.

Communication Loss Family (Tests F~W)

U-type codes appear in pairs: 87 communication loss + 86 Checksum/Counter. Coverage: ACU (U0151), ESC (U0122), EPS (U0131), EMS (U0100), GCU (U0311), BMS (U0111), OBC (U019B), DCDC (U0298), MCUF (U0110), MCUR (U0292), GSM (U0103/104 static/dynamic), EPB (U0159/0243 static/dynamic), CCU (U016B/0456 static/dynamic), PTC (U016E/0166 static/dynamic), IC (U0155), BCM (U0140), iBooster (U0318), IVI (U0156). Group W U007788 PT CAN BusOff: Check PT CAN bus and termination resistor path. Approach: Pre-check connectors → Clear codes and retest → CAN circuit continuity check → Replace corresponding module.

Pedal, Collision, and VCU Self-Check Family (Tests X~Z)

• Group X P160D11 Accelerator pedal 1 fault / P160DF1 Accelerator pedal 2 fault / P100062 Accelerator pedal consistency fault / P160D09 Both accelerator pedal circuits invalid fault: Check accelerator pedal connector and software version → Clear codes and retest → Pedal circuit point-to-point check → Replace pedal/VCU;
• Group Y P100007 Collision fault: Diagnose along collision signal path (SRS→VCU hardwire);
• Group Z P162F44 VCU_E2 self-check fault / P160445 VCU_Ram fault / P16A61C VCU voltage feedback fault / P162FF2 VCU_E2 write fault / P16074B VCU overtemperature fault / P100EF0~2 VCU_ATIC232/280/239 communication loss / P100DF0 VCU operation fault / U029387 VCU message loss / U029383 Checksum error / U029382 Counter fault: VCU board-level and message code family; after clearing codes and retesting, replace VCU based on results.

Thermal Management Family (Tests AE~AP)

• Group AE P1008F1 Battery expansion valve power supply fault / F2 fault / F3 overtemperature / F4 response fault / P100887 communication loss: Diagnose expansion valve circuit;
• Group AF P100787 Four-way valve communication loss / P1007F1 stall / F2 overcurrent / F3 overvoltage / F4 overtemperature / P100786 Checksum; Group AL Lin1 three-way valve (P1006xx) and Lin7 three-way valve (P1005xx) same family: Diagnose six-code groups: stall/overcurrent/overvoltage/overtemperature/communication loss/Checksum;
• Group AG P100412/P100411 Battery inlet water temperature sensor short to power/short to ground: Disconnect sensor connector RCR05 and VCU connector CC52, measure resistance between terminal 1 of RCR05 and terminal C4 of CC52 <1Ω (power circuit VUCC4) → Measure terminal 2 for continuity to ground (ground circuit) → If abnormal, replace sensor;
• Group AH P1C4312/P1C4311 Battery outlet water temperature sensor short to power/short to ground: Disconnect RCR07 and CC51, measure resistance between terminal 1 of RCR07 and terminal H3 of CC51 <1Ω and voltage 5V (power circuit VUBH3) → Terminal 2 continuity to ground → Replace sensor;
• Group AI P100B12/P100B11/P100B01 Coolant level sensor short to power/short to ground/low level: Diagnose coolant level circuit;
• Groups AM~AP: Motor water pump (P1004xx), generator water pump (P1003xx), battery water pump (P1002xx), air conditioning water pump (P1001xx)—each pump has six-code group (frequency/idle/current/overtemperature/voltage/heartbeat signal) diagnosed along the circuit.

Motor Family (Tests AY~BE)

• Group AY P190000 Motor stall fault; Group AZ P190100/P190200 Motor/IGBT temperature high derating warning, P191300 IGBT overtemperature fault, P190A00/P190B00/P191B00 derating and overtemperature family;
• Group BA P191100 Motor forward overspeed fault;
• Group BB B111717/B111716 Auxiliary power supply overvoltage/undervoltage + P191C00/P191D00/P191E00 U/V/W phase current sensor fault + P192000/P192100/P192200 Three-phase zero-drift fault;
• Group BC P192400~P192600 U/V/W software overcurrent + P192700~P192900 hardware overcurrent + P192B00 DC overcurrent + P192C00 Three-phase unbalance + P192D00 Phase loss;
• Group BD P192A00 Bus overvoltage (hardware) fault; Group BE P192E00~P193400 U/V/W IGBT drive high/low side fault—All motor family faults converge with "pre-check → clear codes and retest → motor controller circuit check → replace motor/controller".

Key Parameter Quick Reference

Safety Warnings

• This article is for technical reference. VCU precision tests must be performed by trained and authorized technicians for this vehicle model; high-voltage interlock checks must follow high-voltage safety protocols.
• Power down the vehicle before disconnecting connectors for measurement; never short-circuit the high-voltage interlock loop.
• VCU board-level codes (Ram/E2/voltage feedback/operation fault) have no circuit repair path; replace VCU per procedure and retest.

Repair Insights

The most valuable part of this comprehensive vehicle precision test outline is the "communication loss family pairing rule": All U-type codes appear as 87 communication loss + 86 Checksum/Counter pairs—87 indicates "message not received", 86 indicates "message received but data corrupted"; the diagnostic paths differ: the former checks physical link (wiring harness/CAN termination resistor), the latter checks interference sources and module power. Communication codes covering 17 modules (GCU/BMS/OBC/DCDC/MCUF/MCUR/GSM/EPB/CCU/PTC/IC/BCM/iBooster/IVI/ACU/ESC/EPS/EMS) make this manual a diagnostic index for the entire vehicle CAN topology. The thermal management family also has patterns: each water pump has a six-code group (frequency/idle/current/overtemperature/voltage/heartbeat), each valve has a five-code group (stall/overcurrent/overvoltage/overtemperature/communication)—the "overcurrent+overvoltage+overtemperature" triple code points to driver-side short circuit, while "heartbeat/communication" codes point to LIN link issues. On the measurement side, the two temperature sensor criteria are most practical: inlet RCR05-1↔CC52-C4 <1Ω (pure power supply), outlet RCR07-1↔CC51-H3 <1Ω and 5V (power + reference)—the outlet adds a 5V reference voltage criterion. Finally, remember the convergence for the VCU self-check family (Group Z): Ram/E2/voltage feedback/operation faults are all board-level codes; replace VCU directly.

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【This article is for reference only】