ECI - Self-Diagnosis/Test Connector Location
84mitsubishi02NO. STB-84-14-013
DATE June, 1984
MODEL 1984 Starion; 1984 Turbo Cordia/Tredia
SUBJECT:
ECI SELF-DIAGNOSIS TEST PROCEDURE
Figure 1:
Figure 2:
NEW SELF-DIAGNOSIS CONNECTOR LOCATION
In 1984 Starions and Turbo Cordia/Tredia models built since December, 1983, the ECI self-diagnosis connector has been relocated to a more convenient location under the hood. Figure 1 shows the location for Starion. Figure 2 shows the location for Cordia/Tredia. On earlier 1984 models, the connector is under the dash near the ECI computer. (1983 models do not have the self-diagnosis feature.)
Although the self-diagnosis system and procedure are completely designed in the 1984 Starion and Cordia/ Tredia Service Manuals, the procedures in the Service Manuals are designed for the ECI checker. This bulletin presents a procedure for performing the self-diagnosis test with a LED test light or a high-impedance voltmeter.
WHAT IS SELF-DIAGNOSIS?
Self-diagnosis is the ability of the ECI computer to tell you when a sensor output signal is or has been outside its specified range. The self-diagnosis signal is available any time the ignition is ON.
The self-diagnosis circuitry has a "memory." This means that if a sensor voltage has been out of the specified range any time in the past, the memory of that "failure" is retained, until erased. For example, if a sensor is disconnected any time the ignition is ON, a failed code is retained in memory even though the ignition switch is turned OFF and ON again, and the disconnected sensor may have been re-connected and is in good working order.
The exception to this "memory" feature is the oxygen sensor. The memory of any failure mode of this sensor is erased every time the ignition is turned OFF.
FIGURE 3:
HOW TO READ THE SELF-DIAGNOSIS SIGNAL
The self-diagnosis circuit generates a series of 12-V blips. Each blip or series of blips corresponds to a failure code for one of the eight sensors which feed information to the ECI computer. The blips are of 0.4 second duration. They can be read easily by a LED test light or a high-impedance analog voltmeter. Each series of blips is separated by a two-second interval, and when all failure codes have been given, the series repeats. In the illustration below, Fig. 3, the computer is generating signals for codes 1 and 8.
Each voltage blip produces one blink of the LED test light or one swing of the needle of the analog voltmeter. The sequence will repeat as long as the ignition switch is ON. The chart below shows the self-diagnosis codes and their meanings.
WHEN TO PERFORM A SELF-DIAGNOSIS TEST
If the engine starts hard or not at all, if idle is unstable, or if driveability is poor and basic engine checks (ignition, fuel) show no malfunction, then perform the self-diagnosis test.
Figure 4:
HOW TO PERFORM THE SELF-DIAGNOSIS TEST
1. You will need a LED test light or a high-impedance analog (not digital) voltmeter for the selfdiagnosis test. (An ordinary test light or low-impedance voltmeter can conduct enough current to damage sensitive electronic circuitry, and their use must be avoided.) You can make a LED test light for about $2.00 with materials and circuitry shown in Fig. 4.
Figure 5:
Figure 6:
2. Locate the self-diagnosis connector, or remove cowl kick panels and underdash trim to reach the A-16 terminal cavity in the ECI computer connector. (The A-16 terminals is the self-diagnosis terminal on all 1984 models.)
Connect the voltmeter or LED test light to the selfdiagnosis connector as shown in Fig. 5 or to the A-16 terminal (+) and ground (-) as shown in Fig. 6.
3. Turn the ignition ON and observe the LED test light or voltmeter. Count the number of blinks of the light or swings of the needle and refer to the chart on page 2 to determine which sensor circuit is out of specifications. NOTE:
If you get a code 1, the computer is OK. To test the oxygen sensor, warm up the engine and then drive long enough to get the oxygen sensor working. Then, without shutting off the engine, conduct the self-diagnosis test.
If you get a code 8, it could mean that the engine has been raced with the car stationary. Disconnect the battery for 15 seconds or more to erase the memory, and then try the test again.
NOTE: To avoid damaging the ECU, be sure the ignition is OFF before disconnecting the battery.
When you have completed the self-diagnosis test, perform the necessary repairs or replacements and then disconnect the battery for 30 seconds. Reconnect the battery and perform the self-diagnosis test a final time to verify that the repairs have corrected the condition.