The EEC-IV system may be interrogated for stored codes using the Quick Test
procedures. These tests will reveal faults immediately present during the test
as well as any intermittent codes set within the previous 80 warm up cycles.
If a code was set before a problem self-corrected (such as momentarily loose
connector), the code will be erased if the problem does not reoccur within 80
warm-up cycles.
In 1991 the EEC-VI system check from 2 digit codes to 3 digit codes. These
codes are obtained the same way and the system functions the same. All of the
test procedures apply to both versions of the ECA.
The Quick Test procedure is divided into 2 sections, Key On Engine Off (KOEO)
and Key On Engine Running (KOER). These 2 procedures must be performed correctly
if the system is to run the internal self-checks and provide accurate fault
codes. Codes will be output and displayed as numbers on the hand scan tool,
i.e. 23. If the codes are being read through the dashboard warning lamp, the
codes will be displayed as groups of flashes separated by pauses. Code 23 would
be shown as two flashes, a pause and three more flashes. A longer pause would
occur between codes. If the codes are being read on an analog voltmeter, the
needle sweeps indicate the code digits in the same manner as the lamp flashes.
In all cases, the codes 11 or 111 are used to indicate PASS during testing.
Note that the PASS code may appear, followed by other stored codes. These are
codes from the continuous memory and may indicate intermittent faults, even
though the system does not presently contain the fault. The PASS designation
only indicates the system passes all internal tests at the moment.
CAUTION
To prevent injury and/or property damage, always block the drive wheels, firmly
apply the parking brake, place the transmission in P or N and turn all the electrical
loads off before performing the Quick Test procedures.
- Specific instructions for the use of the tester are included with the tester.
- Plug the tester connectors into the vehicle self-test connectors.
- Set the switches on the tester to the appropriate settings for type of EEC
system and for fast or slow mode. The same information is contained in fast
or slow mode, but the fast mode is 100 times faster than the slow and is for
use with the Super Star Tester.
- Turn on the tester power and depress the test button. Turn ON the vehicle
ignition key.
- The tester will read the codes as they exist.
- Connect the tester as in the KOEO test and start and warm the engine to
normal operating temperature.
- Turn the engine off and depress the test button so it stays in the test
position.
- Restart the engine and the tester will read any existing codes. The tester
will display an engine I.D. code, then on some vehicles a Dynamic Response
code. The final display will be the service codes.
- Turn the vehicle ignition switch to OFF. Set the range of the analog voltmeter
to 0-15 volts.
- Connect the positive lead of an analog voltmeter to the positive of the
battery.
- Connect the negative lead of the voltmeter to the Self-Test Output pin of
the Self-Test connector.
- Connect a jumper wire between the Self-Test Input connector and the Signal
Return pin of the Self-Test connector.
- The needle will sweep 3 times for a code digit of 3, for example. If the
code is 123, the needle will sweep once, pause for 2 seconds, sweep twice,
pause for 2 seconds, then sweep three times. There will be a 4 second pause
between codes. The method of readout of 2 digit codes is similar to the three
digit code readout, but only 2 sets of sweeps will occur.
- The continuous memory codes will be displayed first, then there will be
a 6 second pause, a single sweep, anther 6 second pause then the KOEO codes
will be displayed.
- Connect a jumper wire between the Self-Test Input (STI) connector and the
Signal Return pin of the Self-Test connector.
- This will output the codes to the MIL or Check Engine light on the instrument
panel.
- The light will flash 3 times for a code digit of 3, for example. If the
code is 123, the light will flash once, pause for 2 seconds, flash twice,
pause for 2 seconds, then flash three times. There will be a 4 second pause
between codes. The method of readout for 2 digit code is similar to the three
digit code readout, but only 2 sets of sweeps will occur.
- The continuous memory codes will be displayed first, then there will be
a 6 second pause, a single flash, another 6 second pause, then the KOEO codes
will be displayed.
Once entered, this mode allows the technician to attempt to recreate the intermittent
faults by wiggling or tapping components, wiring or connectors. The test may
by performed during either KOEO or KOER procedures. The test requires the use
of either an analog voltmeter or a hard scan tool.
To enter the continuous monitor mode during KOEO testing, turn the ignition
switch ON. Activate the test, wait 10 seconds, then deactivate and reactivate
the test; the system will enter the continuous monitor mode. Tap, move, or wiggle
the harness, component, or connector suspected of causing the problem; if a
fault is detected, the code will store in the memory. When the fault occurs,
the dash warning lamp will illuminate, the STAR tester will light a red indicator
(and possible beep) and the analog monitor needle will sweep once.
To enter this mode in the KOER test:
- Start the engine and run it at 2000 rpm for two minutes. This action warms
up the oxygen sensor.
- Turn the ignition switch to OFF for 10 seconds.
- Start the engine.
- Activate the test, wait 10 seconds, then deactivate and reactivate the test;
the system will enter the continuous monitor mode.
- Tap, move, or wiggle the harness, component, or connector suspected of causing
the problem; if a fault is detected, the code will store in the memory.
- When the fault occurs, the dash warning lamp will illuminate, the STAR tester
will light the red indicator (and possibly beep) and the analog meter needle
will sweep once.
This testing mode allows the operator to energize the de-energize most of the
outputs controlled by the EEC-IV system. Many of the outputs may be checked
at the component by listening for a click or feeling the item move or engage
by a hand placed on the case. To enter this check:
- Enter the KOEO test mode.
- When all codes have been transmitted, depress the accelerator all the way
to the floor and release it.
- The output actuators are now all ON. Depressing the throttle pedal to the
floor again switches all the actuator outputs OFF.
- This test may be performed as often as necessary, switching between ON and
OFF by depressing the throttle.
- Exit the test by turning the ignition switch OFF, disconnecting the jumper
at the diagnostic connector or releasing the test button on the scan tool.
