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Home >> Lexus >> 2006 >> RX 400h AWD >> Repair and Diagnosis >> Hybrid/Electric Powertrain >> Testing and Diagnosis >> Hybrid Vehicle Control (P310) - RX400H - DTC P0A7A-309 Through P0AA7-727 >> DTC P0AA1-224 Hybrid Battery Positive Contactor Circuit Stuck Closed; DTC P0AA2-225 Hybrid Battery Positive Contactor Circuit Stuck Open >> Description

DTC P0AA1-224 Hybrid Battery Positive Contactor Circuit Stuck Closed; DTC P0AA2-225 Hybrid Battery Positive Contactor Circuit Stuck Open: Description

The SMRs (System Main Relays), installed in the HV relay assembly, connect and disconnect the highvoltage power supply circuit in accordance with requests from the HV control ECU. To ensure a reliable operation, there are three SMRs in total (one for the negative side and two for the positive side).

Fig 1: Hybrid Battery Positive Contactor Circuit Diagram
G04112236Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

To connect, SMR1 and SMR3 turn on initially. Then, SMR2 turns on and SMR1 turns off. This process protects the circuit from the high-voltage surge current by allowing the limit current to flow via the resistor. To disconnect, SMR2 and SMR3 turn off in that order. The HV control ECU checks that the relays have turned off properly.

The HV control ECU monitors operation of the SMRs (CON1, CON2, CON3) to check for malfunctions.

DTC DETECTION CONDITION - TROUBLE AREA CHART

DTC No. INF Code DTC Detection Condition Trouble Area
P0AA1 224 Open or +B short in SMR1 (CON1) circuit
  • Wire harness or connector
  • HV relay assembly
  • HV control ECU
P0AA2 225 Short to GND in the SMR1 (CON1) circuit
  • Wire harness or connector
  • HV relay assembly
  • HV control ECU