Continuous Monitor Test

Fig. 35 Self-test code output format. Continuous monitor test:

The continuous monitor test service codes are separated from the quick test Key-ON, Engine-OFF codes by a single separator pulse, Fig. 35. The service codes that were displayed (repeated) in both the continuous test and on demand test are repaired. The service code(s) displayed in the continuous test are considered the intermittent service codes. This test is intended as an aid in diagnosing intermittent failures in the sensor input circuits. The self-test output is energized whenever the continuous test mode senses a fault (malfunction) and de-energized when the system is satisfactory. To test, connect a volt-ohmmeter or STAR tester onto the self-test output. During the Key-ON, Engine-OFF continuous monitor test, when entering this mode, verify self-test is not activated and turn ignition key to RUN position. The self-test output will be activated whenever a continuous fault (malfunction) is detected and if the fault duration is long enough, a fault code will be stored.
During the engine running continuous monitor test, this mode of testing is entered approximately 2 minutes after the service codes from the engine running portion of the Quick Test. The engine running test can be entered only 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 stop the engine).
The continuous monitor test provides a means to enter this mode of self-test and then attempts to re-create the intermittent failure (tap, move, wiggle the harness and/or the suspected sensor).
If the volt-ohmmeter/STAR tester indicates a fault (short or open) 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 carefully.
2. Enter continuous monitor test.
3. Lightly tap on the sensor.
4. Push and/or pull on the sensor harness electrical connector (do not disconnect).
5. Test and wiggle (shake) harness electrical connector forcefully, working from the sensor electrical connector toward the dash panel and from the dash panel to the processor in short sections.
6. If the volt-ohmmeter or STAR tester has not given a positive indication of an intermittent failure, disconnect sensor from harness electrical connector. Remove terminals from connector, and visually inspect terminals at both ends for corrosion, bad crimps and/or improperly seated terminals.
7. After inspection is completed, connect electrical connector onto sensor.
8. Carefully disconnect harness electrical connector from processor.
9. Inspect terminals. Only remove terminals associated with the sensor being inspected.
10. If the volt-ohmmeter or STAR tester does not give a positive indication of an intermittent failure, connect electrical connector onto processor and erase (clear) the continuous test service codes.
11. To erase (clear) the continuous 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 cleared.