| CAUTION | If ECM replacement is instructed in following testing, always ensure ECM connectors and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. |
Circuit Description
MAP sensor detects manifold pressure as a voltage that is supplied to ECM. Signal is used to determine basic injection duration and basic injection advance angle. ECM will operate in fail-safe mode if DTC P0105 is set. DTC is set when ECM detects an open or short in MAP circuit. Possible causes are
- MAP open or short circuit.
- MAP sensor.
- ECM.
Scheme 43
- Connect scan tool to DLC No. 3 connector. (Scheme 43) Turn ignition on. Using scan tool, read MAP sensor value. If reading is same as atmospheric pressure, go to next step. If reading in not same as atmospheric pressure, check component and ECM connections. Problem is intermittent.
- 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. (Scheme 44) 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. 2 (Light Green/Red wire) and No. 9 (Brown wire) at ECM E5 connector. If voltage is 3.3-3.9 volts, replace ECM and retest. If voltage is not 3.3-3.9 volts, go to next step.
- Check for an open or short circuit in wiring harness between MAP sensor and ECM. See appropriate wiring diagram in «WIRING DIAGRAMS»(ref-22399) article. Repair wiring as necessary. If wiring harness is okay, replace MAP sensor and retest.
