Diagnosis & Repair
- Access ECM behind bottom center of instrument panel, in front of console. Turn ignition on. Backprobing ECM connector, measure voltage between terminals No. 1 (Yellow wire) and No. 9 (Brown wire) at ECM E5 connector. See Figure. If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, replace ECM and retest.
- Backprobing ECM connector, measure voltage between terminals No. 7 (Blue/Yellow wire) and No. 9 (Brown wire) at ECM E5 connector. Disconnect vacuum hose from vapor pressure sensor. Sensor is located in left side of engine compartment, near shock tower. Voltage reading should be as follows:
- 2.9-3.7 volts with no vacuum applied.
- 4.2-4.8 volts with .22 psi (1.5 kPa) applied.
- 1.3-2.1 volts with .59 in. Hg (2.0 kPa) applied.
If voltage is as specified, replace ECM and retest. If voltage is not as specified, go to next step.
- Check for an open or short in wiring harness between vapor pressure sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, replace vapor pressure sensor.