Code 3, Map Sensor
- Turn off ignition. Remove "EFI/ECU" fuse in under-hood relay panel for 10 seconds to reset ECU. Start engine. Warm engine to operating temperature (cooling fan comes on). Check if warning light is on. If not on, problem is intermittent. Test drive and check light again.
- If light is on, turn ignition off. Connect test harness between MAP sensor and sensor harness. Turn ignition on. Measure voltage between Red (pos.) and Green (neg.) terminals. If reading is about 5 volts, go to step 4). If not, measure voltage between Red (pos.) terminal and ground. If voltage is still not 5 volts, go to step 3). If voltage is about 5 volts, repair open in Green/White wire between ECU terminal A16 and MAP sensor.
- Turn ignition off. Connect system checker harness between ECU and ECU connectors. Measure voltage between terminal A7 (pos.) and A16 (neg.) with ignition on. If voltage reading is about 5 volts, repair open Yellow/White wire between ECU terminal A7 and MAP sensor. If voltage is not about 5 volts, substitute a known good ECU. If condition is rectified, replace original ECU.
- Measure voltage between White (pos.) and Green (neg.) terminals. If reading is not about 3 volts, replace MAP sensor or repair short in White/Blue wire between ECU terminal A6 and MAP sensor.
- If measured voltage is about 3 volts, turn ignition off. Connect system checker harness between ECU and ECU connectors. Turn ignition on. Measure voltage between terminals A6 (pos.) and A16 (neg.). If there is not about 3 volts present, repair open White/Blue wire between ECU terminal A6 and MAP sensor.
- If there is about 3 volts present, substitute a known good ECU. If condition is rectified, replace original ECU.