Federal

ECU Testing:

The Mazda Engine Signal Monitor (#49 9200 162) is used to check ECU terminal voltages. This tool inspects individual terminal voltages as selected with the monitor switch. A high impedance volt/ohm meter can also be used to check these voltages. Aftermarket test units are also available that will read ECU terminal voltages when connected with proper adapters.

To use the Engine Signal Monitor, connect unit between ECU and wiring harness with the correct adapter (#49 G018 903). Place pin number cover sheet (#49 G018 904) on monitor face. Turn select and monitor switches to the desired terminal number for a voltage readout. Conduct tests with engine at operating temperature unless instructed otherwise.


CAUTION: Never apply voltage to terminals "A" and "B" of signal monitor.

ECU TESTING PRECAUTIONS [1]

1. If factory test equipment is not available, use only digital volt/ohm meter with minimum 10Meg ohms internal impedance for testing ECU terminal voltages.
2. Never push circuit tester probes into connectors from ECU side.
3. Before replacing an ECU, check components, wiring harnesses and terminal contacts. If terminal voltage readings are incorrect, check for other possible causes (lower than normal or zero voltage may indicate a short to ground in wiring. Higher than normal voltage may indicate an open circuit in wiring between that terminal and the corresponding input/output device, or a poor connection within a harness connector.) Repair as needed and recheck voltage readings.

[1] For more complete information on special precautions regarding handling and testing of electronic components, see Vehicle Damage Warnings.

ECU PIN VOLTAGE CHART

PART 1

ECU Pin Voltage Chart (Part 1):

PART 2

ECU Pin Voltage Chart (Part 2):

PART 3

ECU Pin Voltage Chart (Part 3):

PART 4

ECU Pin Voltage Chart (Part 4):

DECHOKE CONTROL SYSTEM

Dechoke Control System Testing:

1. Check that coolant temperature is below 0°C (32°F).
2. If not, disconnect water thermosensor and connect a resistor of approximately 10K ohms across harness terminals.
3. Turn ignition switch to "START" and verify that injector operating sounds (clicking) are heard.
4. Depress accelerator pedal fully and turn ignition switch to "START." Check that there are now no injector operating sounds.
5. If not as specified, check wiring, connectors and individual components such as water thermosensor, throttle sensor and injectors.