ECI System - Voltmeter Check Procedure: Overview

84mitsubishi02

NO. STB-84-14-014

DATE July, 1984

MODEL 1983, 1984 Starion; 1984 Turbo Cordia/Tredia
SUBJECT:

1983, 1984 ECI SYSTEM VOLTMETER CHECK PROCEDURE
USE OF VOLTMETER TO TEST ECI SYSTEM

The ECI system on 1983 and 1984 Starions and 1984 Turbo Cordia/Tredia models can be checked using a multimeter or any high-impedance voltmeter. This method is useful when checking the ECI system without unplugging the computer (and consequently erasing the memory) or when the ECI checker is not available.

Figure 1:

VOLTMETER PROBES AND CONNECTIONS

To perform the tests in this bulletin, voltages will be measured right at the computer which is on the right cowl kick panel. Make up a set of thin probes from stiff wire to attach to your voltmeter and insert into the tops of the connectors on the computer as shown in Figure 1. You don't have to unplug the connectors, but you may findit convenient to remove the computer from the kick panel to make it easier to reach the connector terminals.
CAUTION: Short-circuiting the positive (+) probe between a connector terminal and ground could damage the vehicle wiring, the sensor, the ECU, or all three. Use care to prevent this! Insulate the exposed part of the probe with insulating material as a precaution.

Figure 2:

Figure 3:

TEST PROCEDURE
1. Remove the right side kick panel and the trim panel below the glovebox to reach the computer terminal connectors.
2. Attach the black lead of your voltmeter to a good ground - the computer box is good.
3. Refer to the appropriate ECI Voltmeter Check Charts I and II for the car you are checking. Note the connector terminal callouts in the right column. Insert the positive probe into each connector terminal in turn. Switch the ignition from OFF to ON, and compare the voltage with that shown in the chart. For example, when the probe is on terminal A1, the voltmeter should read between 0 and 0.6V as shown in Fig. 2 with the accelerator closed, and 4-5V when the accelerator is open.
4. Proceed until you have checked all the terminals in Chart 1, or until a voltage is found that is out of specification. If you obtain a voltage reading out of specification, go to Step 5. If all voltages are within specification, go to Step 6.
5. When you find a voltage that is out of specification (except TPS), measure sensor voltage output at the sensor terminal of the same color wire as in the computer terminal for that sensor. Fig- ure 3 shows a typical example. This tells you whether the voltage variation is in the sensor or in connectors and wiring.

Correct any loose connections, replace sensors as required, and then disconnect the battery for 30 seconds to erase the computer's memory of the malfunction. Re-check the appropriate terminal to verify that the malfunction has been corrected.

NOTE:
If the TPS voltage is out of specification, remember that the TPS produces a failure signal if the throttle is blipped when shutting down the engine. Restart the engine and then let it stop it stop without depressing the accelerator. Measure the TPS voltage at the computer, and, if necessary, at the sensor connector.
6. Perform the checks in Chart II. If an out-ofspecification voltage is found, locate the sensor and measure its output right at the connector. If OK, then you know the wiring or connector is the source of the discrepancy.

NOTE If the oxygen sensor voltage is out of specification, drive the car until it is warm enough to activate the oxygen sensor and then without shutting off the engine, measure the voltage output of the oxygen sensor at the computer.
7. Correct connections and replace sensors as required, and then disconnect the battery for 30 seconds to erase the computer's memory of the malfunction. Re-check the appropriate terminal to verify that the malfunction has been corrected.

NOTE:
To prevent damage to the computer, be sure the ignition switch is OFF before disconnecting the battery cable.

It is not necessary to perform the tests in any prescribed sequence. We recommend beginning with the "ignition OFF-ON" series and ending with the "IDLE" series. For convenience, begin with connector "A" and then go to connector "B"