Monitors, Trips, Drive Cycles and Readiness Codes

DTC TEST DESCRIPTIONS
The self-diagnostic tests run to determine if a subsystem has passed or failed a specified test. After a test is performed the PCM/TCM will record test PASS/FAIL criteria for display with a Scan fool. Each code will have three records and are as follows:
- LAST TEST - Indicates whether the diagnostic reported a test passed or failed the last time it ran. (Even if it was not this ignition cycle.) possible display: PASSED, FAILED, NOT RAN.
- THIS IGNITION - Indicates if diagnostic test has run this ignition cycle and the results of that test(s). Possible display: PASSED, FAILED, PASS & FAIL NOT RAN.
- SINCE CLEAR - Indicates if diagnostic test has run since DTCs were cleared and the results of that test(s). Possible display: PASSED, FAILED, PASS & FAIL NOT RAN HISTORY.

TRIP
A "TRIP" is defined as an ignition key On. Run. Off cycle in which all the criteria were met for a given diagnostic test to run. During any given drive cycle key On-Run-key Off, criteria may or may not have been met to perform all diagnostic tests. No "TRIP" will occur for a given diagnostic until the vehicle is driven in such a manner as to meet all enable criteria. If a test is desired on a particular subsystem to determine if it "passes" or "fails" refer to the specific DTC for test parameters. The parameters are calibrated conditions the PCM/TCM requires in order to perform the test. If a test has not been run, monitor the Scan tool pass/fail code status at the time the parameters have been met.
Last Test Failed - Indicates that the last time a diagnostic test was performed on a particular system or sub-system it failed. A problem may no longer exist, but since another test has not been run, the fault still appears failed. A status will remain between ignition cycles if a test was not run and did not pass prior to turning Off the ignition.
MIL Requested - Indicates whether a diagnostic code is requesting the MIL to be illuminated.
It is important to remember the DTC as well as any stored freeze Frame/failure record will be erased if a clear code command is issued to the PCM/TCM. DTCs and freeze frame/failure records will also be erased if 40 passes have been recorded without any faults. The emission DTCs (type A or B) will use a separate counter from the non-emission (type C) DTCs.

Warm Up Cycle
A warm-up cycle is defined as engine temperature reaching a minimum of 71°C (160°F) and a rise in temperature of at least 22°C (40° F) over the course of a trip.