Toyota Cressida and Van 1983-1990

Electronic Control Unit (ECU)

Print

OPERATION





Click image to see an enlarged view

Fig. Fig. 1 The Electronic Control Unit (ECU) on the Van is located in the drivers side pillar



Click image to see an enlarged view

Fig. Fig. 2 The Electronic Control Unit (ECU) on the Cressida is located under the passenger's side dash

The ECU 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 ECU is a very fragile and expensive component. Always follow the precautions when servicing the electronic control system.

PRECAUTIONS





Do not permit parts to receive a severe impact during removal or installation. Always handle all fuel injection parts with care, especially the ECU. DO NOT open the ECU cover!
 
Before removing the fuel injected wiring connectors, terminals, etc., 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 tasnsistor 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.
 

ECU Connectors Voltage


Click image to see an enlarged view

Fig. Fig. 3 Voltage specifications at the ECU connectors-1983-84 Cressida



Click image to see an enlarged view

Fig. Fig. 4 Voltage specifications at the ECU connectors -1985-88 Cressida



Click image to see an enlarged view

Fig. Fig. 5 Voltage specifications at the ECU connectors -1989-90 Cressida



Click image to see an enlarged view

Fig. Fig. 6 Voltage specifications at the ECU connectors -1984-85 Van



Click image to see an enlarged view

Fig. Fig. 7 Voltage specifications at the ECU connectors -1986-89 Van

The EFI circuit can be checked by measuring the resistance and the voltage at the wiring connectors of the ECU. The following list should be followed before making the ECU inspection:

  1. Perform all voltage measurements with the connectors attached.
  2.  
  3. Verify that the battery voltage is 11 volts or more when the ignition switch is turned OFF.
  4.  
  5. The testing probes must not make contact with the ECU Ox and Vf terminals.
  6.  
  7. Remove the glove box, turn the ignition switch to the ON position and measure the voltage at each terminal.
  8.  

ECU Connectors Resistance


Click image to see an enlarged view

Fig. Fig. 8 Resistance specifications at the ECU connectors-1985-88 Cressida



Click image to see an enlarged view

Fig. Fig. 9 Resistance specifications at the ECU connectors-1989-90 Cressida



Click image to see an enlarged view

Fig. Fig. 10 Resistance specifications at the ECU connectors-1983-85 Van



Click image to see an enlarged view

Fig. Fig. 11 Resistance specifications at the ECU connectors-1986-89 Van



Click image to see an enlarged view

Fig. Fig. 12 When testing the resistance of the ECU, the test probe should be carefully inserted into the wiring connector from the wiring side. Do not damage the connector

Be sure not to touch the ECU terminals. The tester probe should be inserted into the wiring connector from the wiring side.

  1. Remove the glove box. Unplug the wiring connectors from the ECU.
  2.  
  3. Measure the resistance between each terminal of the wiring connector.
  4.  

REMOVAL & INSTALLATION



  1. Disconnect the negative battery cable.
  2.  
  3. Locate the ECU and release the lock, then pull out the connector. Pull on the connectors only!
  4.  
  5. Unbolt the ECU from its mounting area.
  6.  

To install:

  1. Mount the ECU on the vehicle in the proper location.
  2.  
  3. Fully insert the connector, then check that it is locked.
  4.  

 
label.common.footer.alt.autozoneLogo