Continuous Monitor Test

Fig. 23 Self-test code output format. Continuous monitor test:

The continuous monitor test service codes are separate from the Quick Test Key-ON, Engine-OFF codes by a single separator pulse, Fig. 23. The continuous monitor codes should never be used for diagnosis until the Key-On, Engine-OFF and Engine Running tests result in a pass code 11.
The service codes that were displayed (repeated) in both the continuous monitor and engine running tests are considered repaired. The unique service code(s) displayed only in continuous monitor test are considered the intermittent service codes. During this mode of testing, inputs to the processor for circuit opens or shorts are monitored. The continuous monitor test codes must be retrieved within 20 engine temperature warm up cycles. On the twenty first engine temperature cycle, the service code will be automatically erased. The continuous monitor codes can also be erased by deactivating quick test while the service codes are being outputted.
The continuous monitor test is intended as an aid in diagnosing intermittent failures in the sensor input circuits. The self-test output is energized whenever the continuous memory mode senses a fault and de-energized when the system is satisfactory. To enter the Key-ON, Engine-OFF continuous monitor test, verify that the self-test is not activated and then turn the ignition switch to RUN position. The self-test output will be activated whenever a continuous fault is detected and, if the duration is long enough, a fault will be stored. The Engine Running continuous monitor test mode is entered approximately 2 minutes after the service codes from the Engine Running portion of the quick test. The Engine Running test can only be entered once per ignition cycle. An alternate quick method (eliminates waiting for self-test to complete its cycle) is to enter the running test, stop, and re-enter (do not switch ignition OFF). The continuous monitor test provides a means of entering this mode of self-test and no attempt to re-create the intermittent failure (tap, wiggle the harness and/or the suspected sensor). If the volt-ohmmeter/STAR tester indicates a fault (short or open circuit) the corresponding service code will be stored. Proceed with the following example on how to use the continuous test systematically.
If a service code 51 was displayed (engine coolant temperature sensor), proceed as follows:
1. Visually inspect the sensor closely.
2. Enter the continuous monitor test, then lightly tap the sensor.
3. Push and/or pull on the sensor harness electrical connector (do not disconnect).
4. Test, then wiggle (shake) harness vigorously, working from the sensor connector toward the dash panel from the dash to the processor. Work in short sections.
5. If the volt-ohmmeter has not given a positive indication of an intermittent fault, carefully disconnect sensor from harness connector. Remove terminals from connector. Inspect terminals at both ends for corrosion, bad crimps and improperly seated terminals.
6. After inspection, connect harness connector onto sensor.
7. Disconnect processor from harness.
8. Inspect terminals, then remove terminals only associated with the sensor being inspected.
9. If the volt-ohmmeter does not give a positive intermittent fault indication, connect and erase the continuous test service codes.
10. To erase the service codes, proceed as follows:
a. Initiate Key-ON, Engine OFF self-test.
b. Remove jumper wire from self-test input terminal as soon as the first service code is received (even if an 11 is the first code).
c. Repeat self-test with jumper wire to verify service codes have been erased.