Nissan 240SX/Altima 1993-1998 Repair Guide

Engine Control Module (ECM)

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OPERATION



The Engine Control Module (ECM) performs many functions. The module receives data from various engine sensors and computes the required fuel flow rate necessary to maintain correct air/fuel ratio throughout the entire engine operational range.

Based on the data received and information programmed into the ECM's memory, the ECM generates output signals to control relays, actuators and solenoids. The module automatically senses and compensates for any changes in altitude when driving the vehicle.

The ECM consists of a microcomputer, inspection lamps, a diagnostic mode selector, and connectors for signal input, signal output, power supply and ground. The unit is located under the center console, at the firewall on the Altima, and in the passenger's side kick panel on the 240SX.

REMOVAL & INSTALLATION



See Figure 1



Click image to see an enlarged view

Fig. Fig. 1: On the Altima, the ECM is located behind an access panel at the front of the console

Electrostatic Discharge (ESD) can ruin sensitive electronic components. Always wear a grounding strap or discharge electricity to a good ground prior to handling any electronic components.

  1. Disconnect the negative battery cable.
  2.  
  3. On the Altima, remove the center console.
  4.  
  5. On the 240SX, remove the passenger's side kick panel.
  6.  
  7. Label and disconnect the ECM electrical harness.
  8.  
  9. Remove the ECM mounting screws.
  10.  
  11. Carefully remove the ECM from the vehicle.
  12.  

To install:
  1. Position the ECM in the vehicle and tighten the mounting screws securely.
  2.  
  3. Connect the ECM electrical harness.
  4.  
  5. On the 240SX, install the passenger's side kick panel.
  6.  
  7. On the Altima, install the center console.
  8.  
  9. Connect the negative battery cable.
  10.  
  11. Start the vehicle and verify proper operation.
  12.  
  13. Read and clear the ECM trouble code memory.
  14.  

 
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