| DETECTED CONDITION | POSSIBLE CAUSE |
| IAP sensor voltage is out of the specified range. 0.1 V ≤ Sensor voltage ≤ 4.8 V NOTE: Note that atmospheric pressure varies depending on weather conditions as well as altitude. Take that into consideration when inspecting voltage. | • Clogged vacuum passage between throttle body and IAP sensor. • Air being drawn from vacuum passage between throttle body and IAP sensor. • IAP sensor circuit open or shorted to ground. • IAP sensor malfunction. • ECM malfunction. |
Inspection
Step 1
1) Lift and support the fuel tank. (5-7)
2) Turn the ignition switch OFF.
3) Check the IAP sensor coupler for loose or poor contacts. If OK, then measure the IAP sensor input voltage.
4) Disconnect the IAP sensor coupler.
5) Turn the ignition switch ON.
6) Measure the voltage at the Red wire (1) and ground.
If OK, then measure the voltage at the Red wire (1) and B/Br wire (2).
- IAP sensor input voltage: 4.5-5.5 V
- ((+) Red - (-) Ground)
- ((+) Red - (-) B/Br)
- 09900-25008: Multi circuit tester set
- Tester knob indication: Voltage (⎓)
Is the voltage OK?
| YES | Go to Step 2 |
| NO | • Loose or poor contacts on the ECM coupler. • Open or short circuit in the Red wire or B/Br wire. |
Step 2
1) Connect the IAP sensor coupler.
2) Insert the needle pointed probes to the lead wire coupler.
3) Start the engine at idle speed.
4) Measure the IAP sensor output voltage at the wire side coupler (between G/B and B/Br wires).
- IAP sensor output voltage: Approx. 2.7 V at idle speed ((+) G/B - (-) B/Br)
- 09900-25008: Multi circuit tester set
- 09900-25009: Needle pointed probe set
- Tester knob indication: Voltage (⎓)
| YES | Go to Step 3 |
| NO | • Check the vacuum hose and the passage of throttle body vacuum for crack or damage. • Open or short circuit in the G/B wire. • Replace the IAP sensor with a new one. |
Step 3
1) Remove the IAP sensor. (4-49)
2) Connect the vacuum pump gauge to the vacuum port of the IAP sensor.
Arrange 3 new 1.5 V batteries in series (1) (check that total voltage is 4.5-5.0 V) and connect (-) terminal to the ground terminal and (+) terminal to the Vcc (2) terminal.
Check the voltage between Vout (3) and ground. Also, check if voltage reduces when vacuum is applied up to 400 mmHg by using vacuum pump gauge.
- 09917-47011: Vacuum pump gauge
- 09900-25008: Multi circuit tester set
- Tester knob indication: Voltage (⎓)
Is the voltage OK?
| YES | • Red, G/B or B/Br wire open or shorted to ground, or poor (10), (16) or (34) connection. • If wire and connection are OK, intermittent trouble or faulty ECM. • Recheck each terminal and wire harness for open circuit and poor connection. |
| NO | If check result is not satisfactory, replace IAP sensor with a new one. |
Output voltage (Vcc voltage 4.5 V, ambient temp. 25°C, 77°F)
| ALTITUDE (Reference) | ATMOSPHERIC PRESSURE | OUTPUT VOLTAGE | ||
| (ft) | (m) | (mmHg) | kPa | (V) |
| 0 | 2000 | 0 | 610 | 760 | 707 | 100 | 94 | Approx. 3.3-3.6 |
| 2001 | 5000 | 611 | 1524 | 707 | 634 | 94 | 85 | Approx. 3.0-3.3 |
| 5001 | 8000 | 1525 | 2438 | 634 | 567 | 85 | 76 | Approx. 2.7-3.0 |
| 8001 | 10000 | 2439 | 3048 | 567 | 526 | 76 | 70 | Approx. 2.5-2.7 |