Toyota Celica 1994-1998 Repair Guide

Engine Control Module (ECM)

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OPERATION



The ECM receives signals from various sensors on the engine. It will then process this information and calculate the correct air/fuel mixture under all operating conditions. The ECM is a very fragile and expensive component. Always follow the precautions when servicing the electronic control system.

PRECAUTIONS



See Figure 1


CAUTION
Work must be started after 90 seconds from the time the ignition switch is turned to the LOCK position and the negative battery cable has been disconnected. The SRS is equipped with a back-up power source so that if work is started within 90 seconds of disconnecting the negative battery cable, the SRS may deploy. When the negative terminal cable is disconnected from the battery, memory of the clock and radio will be canceled. Before you start working, make a note of the contents memorized by the audio memory system. When you have finished working, reset the audio systems and adjust the clock. Never use a back-up power supply from outside the vehicle.



Do not permit parts to receive a severe impact during removal or installation. Always handle all fuel injection parts with care, especially the ECM. DO NOT open the ECM cover!
 
Before removing the fuel injected wiring connectors, terminals, ect., first disconnect the power by either disconnecting the negative battery cable or turning the ignition switch OFF .
 
Always check the diagnostic trouble code before disconnecting the terminal cable from the battery.
 
Do not be careless during troubleshooting as there are numerous amounts of transistor circuits; even a slight terminal contact can induce troubles.
 
When inspecting during rainy days, take extra caution not to allow entry of water in or on the unit. When washing the engine compartment, prevent water from getting on the fuel injection parts and wiring connectors.
 



Click image to see an enlarged view

Fig. Fig. 1: DO NOT drop the ECM!

REMOVAL & INSTALLATION



See Figure 2

The ECM is located under the dash on the drivers side near the center console.

  1. Disconnect the negative battery cable. Wait at least 90 seconds once the negative battery cable id disconnected to perform work on the vehicle to hinder air bag deployment.
  2.  



Click image to see an enlarged view

Fig. Fig. 2: Location view of the Electronic Control Module (ECM)


CAUTION
Work must be started after 90 seconds from the time the ignition switch is turned to the LOCK position and the negative battery cable has been disconnected. The SRS is equipped with a back-up power source so that if work is started within 90 seconds of disconnecting the negative battery cable, the SRS may deploy. When the negative terminal cable is disconnected from the battery, memory of the clock and radio will be canceled. Before you start working, make a note of the contents memorized by the audio memory system. When you have finished working, reset the audio systems and adjust the clock. Never use a back-up power supply from outside the vehicle.

  1. Remove any necessary trim panel to gain access to the ECM floor mat bracket bolts.
  2.  
  3. Remove the ECM floor mat bracket bolts.
  4.  
  5. Locate the ECM and release the lock, then pull out the connector. Pull on the connectors only!
  6.  
  7. Unbolt the ECM from its mounting area.
  8.  

To install:
  1. Install the ECM floor mat bracket bolts.
  2.  
  3. Fully insert the connector, then check that it is locked.
  4.  
  5. Install any necessary trim panel. Reconnect the negative battery cable.
  6.  
  7. Start engine and check for proper operation.
  8.  

 
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