Toyota Corolla 1988-1997 Repair Guide

Electronic Control Module (ECM)



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.


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 .
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.


See Figure 1

  1. Disconnect the negative battery cable.

On models with an airbag, wait at least 90 seconds from the time that the ignition switch is turned to the LOCK position and the battery is disconnected before performing any further work. Refer to Drive Train for all air bag warnings.

  1. Remove any necessary trim panel to gain access to the ECM floor mat bracket bolts.
  3. Remove the ECM floor mat bracket bolts.

Click image to see an enlarged view

Fig. Fig. 1: Remove the floor mat bracket attached to the side of the ECM

  1. Locate the ECM and release the lock, then pull out the connector. Pull on the connectors only!
  3. Unbolt the ECM from its mounting area.

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