Alliance/Encore L4-1721cc 105 CID (1985)
Manifold Pressure/Vacuum Sensor: Testing and Inspection
Renix Throttle Body Fuel Injection (TBFI), Early Type System
1.
Inspect MAP hose and connections at throttle body and sensor. Repair as necessary.
2.
With ignition switch On and engine Off, check MAP sensor output voltage at MAP sensor connector terminal B (marked on sensor body). Output
voltage should be 4 to 5 volts.
3.
Test ECU connector terminal J2-12 for voltage. Voltage should be the same as recorded in step 2. If not, repair wire harness as necessary between
sensor and ECU connectors.
4.
Check MAP sensor supply voltage at MAP sensor connector terminal C (marked on sensor body). Supply voltage should be 4.5 to 5.5 volts.
5.
Test ECU connector terminal J2-2 for voltage. Voltage should be the same as recorded in step 4. If not, repair wire harness as necessary between
sensor and ECU connectors.
6.
Test MAP sensor ground circuit at MAP sensor connector terminal A (marked on sensor body) and ECU connector terminal J2-13. Repair wire
harness as necessary.
7.
Test MAP sensor ground circuit again at ECU connector terminals J1-F and J2-13 with an ohmmeter. If an open circuit is indicated, inspect sensor
ground connection on flywheel/flexplate housing and repair as necessary. If ground connection is satisfactory, replace ECU. If ECU connector
terminal J2-13 indicates 12 volts, repair condition before replacing ECU.
