| WARNING | Read service precautions before proceeding with service procedure. See SERVICE PRECAUTIONS . |
| CAUTION | If Engine Control Module (ECM) replacement is instructed in following test, always ensure ECM electrical connectors and ground circuits are okay. If either are defective, repair and repeat testing to confirm ECM malfunction. |
Note. If DTCs P1430, P1431, P0110, P0115, P0120 and P0121are output simultaneously, the E2 sensor ground circuit at terminal No. 18 (Brown wire) at ECM electrical connector E8 may be open. See WIRING DIAGRAMS article. For ECM electrical connector terminal identification (Схема №7) It may be necessary to check Brown wire between splice I7 and terminal No. 18 at ECM electrical connector E8. Splice I7 is located behind passenger's side of instrument panel. (Схема №10)
Circuit Description
Vacuum sensor provides input signals to ECM for controlling the Hydrocarbon Adsorber Catalyst (HCAC) system. DTC is set if a problem exists with the vacuum sensor. Possible causes are
- Defective vacuum sensor.
- Defective vacuum line for vacuum sensor.
Diagnostic Aids
If problem exists with by-pass valve for HCAC system, it is possible that DTC P1431 will be set before DTC P1436 and DTC P1437. Using Toyota hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.