49 Readiness Test Tips
Readiness Test Tips- If all of the conditions for running the EVAP Leak Detection Test (see "Enabling Conditions to Run EVAP Leak Detection Test") are not met, the tests will not run and could lead to misdiagnosis.
If the "battery temperature" valve displayed on the scan tool is too high, you can blow cool air on the PCM with a fan to cool the PCM sensor that estimates battery temperature. If "battery temperature" is too low, try warning the PCM by blowing warm air on it. However, do not expose the PCM to extreme temperatures or the PCM could be damaged.
- If the Readiness Test does not complete or if you want to quickly determine if a fault condition is still present, you can perform a quick check of the EVAP system as follows. The readiness test will not complete, because purge will not take place, but you will be able to see if the PCM detects any problems that could set DTC 184, 187, 160, or 161.
Connect a test light, logic probe, or voltmeter between the LDP solenoid control terminal (E-40, terminal 3) and B+ by backprobing into the connector with the harness connected to the LDP.
When the PCM energizes the LDP solenoid, you will hear a click from the LDP and your tester will indicate that the solenoid is turned on. (You can also touch the LDP and feel the solenoid clicking.) Refer to the EVAP Leak Detection Test Sequence chart. Compare the LDP solenoid activity with the monitor sequence in the chart. As each section of the test runs, this indicates that the previous section passed successfully. By watching to see which tests complete, you can see if any conditions are present that the PCM considers abnormal.
- When performing the above quick check procedure, if the engine coolant temperature (ECT) reading on the scan tool is not within ± 5.6°C (10°F) of "battery temperature" reading, it may be necessary for the vehicle to sit several hours to cool sufficiently. Or you can save time by substituting an inexpensive resistor for the ECT sensor to bring the reading into the required range. This will also allow you to run the test repeatedly (if necessary) since the resistor provides a consistent ECT reading within the required temperature range.
Insert a resistor as follows to change the coolant temperature reading to meet required monitor conditions:
a. Turn the ignition switch to OFF.
b. Disconnect the coolant temperature sensor.
c. Note the battery temperature reading on the scan tool.
d. The chart lists three resistor values that will cover the temperature range for the EVAP leak detection test to run. Select a resistor value that will bring the ECT reading to within ± 5.6°C (10°F) of the battery temperature reading.
CAUTION: To prevent damaging the connector, use only a 1/2 watt resistor (Radio Shack or equivalent) which has the correct lead diameter to properly fit into the connector terminals.
e. Bend the resistor leads so they are parallel and spaced the same distance apart as the coolant temperature sensor terminal pins.
f. Insert the resistor leads into the ECT harness connector in place of the ECT.
g. Turn the A/C on at maximum setting so that the cooling fan will come on when the engine is running. If the vehicle is not equipped with A/C, use a jumper wire between the cooling fan and B+ to activate the fan.
h. Turn the ignition switch to ON and confirm that the engine coolant temperature (ECT) reading on the scan tool is within 10°F of "battery temperature" reading. Clear any DTCs from PCM memory that may have set. Then continue with the Readiness Test procedure. 48 Readiness Test