Toyota Celica/Supra 1971-1985 Repair Guide

Electronic Control Module (ECM)



The ECM receives signals from various sensors on the engine. It then processes this information and calculates 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.

The ECM computer is located below the instrument panel in the left kick panel on 1979-81 Liftbacks, and underneath the glove box area on other fuel injected Celicas and Supras.


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.


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

To install:
  1. Mount the ECM on the vehicle in the proper location.
  3. Fully insert the connector, then check that it is locked.