| 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 P0121 are 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 see scheme 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. see scheme 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 circuit. Possible causes are
- Vacuum sensor circuit is open or shorted.
- Defective vacuum sensor.
- Defective ECM.
Diagnostic Aids
After confirming DTC P1430, if Toyota hand-held tester is available, use hand-held tester to access CURRENT DATA to confirm vacuum sensor pressure. If vacuum sensor pressure is zero psi, HCLS circuit may be shorted. If vacuum sensor pressure is 18.85 psi (1.3 kg/cm 2 ) or more, VC circuit may be open or shorted, HCLS circuit may be open or E2 circuit may be open. Using hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.
Scheme 326
- If Toyota hand-held tester is available, go to next step. If Toyota hand-held tester is not available, go to step, 3.
- Connect hand-held tester to Data Link Connector (DLC) No. 3. see scheme 2 Turn ignition on and then turn hand-held tester on. Using hand-held tester, access CURRENT DATA and read vacuum sensor pressure. If vacuum sensor pressure is not the same as the atmospheric pressure, go to next step. If vacuum sensor pressure is the same as the atmospheric pressure, problem is intermittent. Check for defective connections or intermittent problem in wiring between ECM and vacuum sensor. ECM is located behind glove box. see scheme 3 Vacuum sensor is located at passenger's side front corner of the engine and contains Black 3-pin electrical connector with Brown, Violet/White and Yellow/Red wires. (Scheme 326)
- Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 3 Ensure ignition is on. Using voltmeter, check voltage between terminals No. 2 (Yellow/Red wire) and No. 18 (Brown wire) at ECM electrical connector E8. see scheme 7 This is the VC and E2 terminals on ECM. Voltage should be 4.5-5.5 volts. If voltage is within specification, go to next step. If voltage is not within not specification, replace ECM.
- Ensure ignition is on. Using voltmeter, check voltage between body ground and terminal No. 14 (Violet/White wire) at ECM electrical connector E9. see scheme 7 This is the HCLS terminal on ECM. Voltage should be 3.3-3.9 volts. If voltage is not within specification, go to next step. If voltage is within specification, replace ECM.
- Check for open and short in wiring harness and electrical connectors between vacuum sensor and ECM. See WIRING DIAGRAMS article. Vacuum sensor is located at passenger's side front corner of the engine and contains Black 3-pin electrical connector with Brown, Violet/White and Yellow/Red wires. (Scheme 326) If wiring harness and electrical connectors are okay, replace vacuum sensor. If wiring harness or electrical connector is defective, repair as necessary.