Manifold Pressure/Vacuum Sensor: Testing and Inspection

Fig. 3 ECU connector terminal identification:

Fig. 6 Manifold Absolute Pressure (MAP) sensor terminal identification:

1. Check vacuum hose connectors at throttle body and sensor, and repair as necessary.
2. Using a suitable voltmeter, check MAP sensor output voltage at MAP electrical connector terminal B, Fig. 6, with ignition switch in the On position, engine off. Output voltage should be 4 to 5 volts. If voltage is not as indicated, check ECU terminal C-6 for a voltage reading of 4 to 5 volts to ensure wiring is satisfactory, Fig. 3. If wiring is satisfactory, check ECU with diagnostic tester M.S. 1700.
3. With ignition switch in the On position, check MAP sensor supply voltage at MAP electrical connector C. Voltage reading should be 4.5 to 5.5 volts. If voltage is not as indicated, check for voltage reading of 4.5 to 5.5 volts at ECU electrical connector terminal C-14 to ensure wiring is satisfactory. If wiring is satisfactory, check ECU with diagnostic tester M.S. 1700.
4. Using an ohmmeter, check MAP sensor ground circuit at sensor connector terminal A and ECU connector terminal D-3. Repair wiring a necessary, if continuity does not exist. If wiring is satisfactory, but continuity does not exist proceed to step 5.
5. Check MAP sensor ground circuit at ECU, by connecting an ohmmeter between ECU electrical terminals D-3 and B-11. If continuity does not exist, check for defective ground wire connection at right hand side of cylinder block. If ground is connection is satisfactory, replace ECU. If terminals D-3 is shorted to 12 volts, correct this condition before installing replacement ECU.