Diagnosis & Repair
WARNING: This page is about a different car, the 2002 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.
- 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 at driver's side of instrument panel. See Figure. 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 Figure. 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. See Fig 1.
- Remove glove box for access to ECM with electrical connectors still installed on ECM. See Figure. 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 Figure. 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 Figure. 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. See Fig 1. If wiring harness and electrical connectors are okay, replace vacuum sensor. If wiring harness or electrical connector is defective, repair as necessary.