Mazda 323/626/929/GLC/MX-6/RX-7 1978-1989

Engine Control Unit (ECU)

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OPERATION



As the electronic brain of a closed loop system, the engine control unit receives data from a number of vehicle-mounted sensors. Such data pertains to (but is not limited to) engine speed, coolant temperature, exhaust gas oxygen content, manifold vacuum and throttle valve position. In response to these ongoing inputs, the ECU continually controls the operation of a series of solenoid valves in order to maintain optimal operating conditions. As an example of its many functions, the ECU determines the operating period of the Air/Fuel (A/F) solenoid and controls the air/fuel ratio.


WARNING
The ECU is a very sensitive and EXPENSIVE electronic component. NEVER disconnect power from the ECU (or any computer module) with the ignition key turned ON, as this could destroy the module. This warning includes disconnecting the battery cables. If the cables are removed with the key turned ON, this will remove power from the ECU and quite possibly destroy it.

REMOVAL & INSTALLATION



  1. Disconnect the negative battery cable.
  2.  
  3. Remove the passenger and driver side cover walls from the center console unit.
  4.  
  5. Detach the ECU electrical connectors.
  6.  
  7. Unfasten the mounting bolts/nuts and remove the ECU.
  8.  

To install:
  1. Position the ECU and fasten its mounting hardware.
  2.  
  3. Attach the electrical connectors.
  4.  
  5. Install the passenger and driver side cover walls on the center console unit.
  6.  
  7. Connect the negative battery cable.
  8.  

 
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