Using Diagnostic Tables
Using Diagnostic Trouble Code TablesWhen diagnosing powertrain problems, you will almost certainly need to use the diagnostic procedures found under Powertrain Management. These diagnostic procedures are mostly in the form of tables. At the beginning of each Diagnostic Trouble Code (DTC) will be a circuit diagram, descriptions and notes about the condition or DTC diagnosed in the table. Reading this Diagnostic Support Information will help you understand the DTC or condition and what the table is trying to accomplish. Below are explanations of the diagnostic support information and tables for DTC(s).
Circuit Diagram
The circuit diagram of the diagnostic support information will show the circuits and components involved in setting the DTC. This diagram may be used as a reference when circuit checks are required in the table. If more detailed circuit information is required, Diagrams / Electrical may be referenced.
Circuit Description
The circuit description explains the sensor and/or circuits involved in setting the DTC. It also gives a brief description of when the DTC is set.
Test Conditions
The test conditions are the conditions that must be met before the PCM will test for a failure. These conditions are generally set up so that an input or system may be reliably checked and not give a false failure indication.
Failure Condition
The failure conditions are the conditions that must be met for the DTC to set. Failure conditions are checked only after the test conditions (described above) have been met. If they are true, then an input or system failure is present and the DTC is set.
Action Taken When The DTC Sets
The actions taken are the steps the PCM takes after the DTC is set. These actions serve one of three purposes:
1. To inform the driver of the problem.
2. To preserve the driveability of the vehicle.
3. To prevent the failure from causing any damage to the vehicle.
Conditions For Clearing The MIL / DTC
These are the conditions that must be met for the Malfunction Indicator Lamp (MIL) to go OFF and / or the DTC to clear.
Diagnostic Aids
Most tables have one result which reads Fault not present. This means that the conditions that were present when the DTC set are no longer there. Sometimes, with the help of snapshot on DTC set data or information from the driver, the problem may still be identified or at least narrowed down to a short list of possible intermittent failures. When this is true, the Diagnostic Aids may explain what to look for and which direction to head in looking for an intermittent failure.
Test Description
The Test Descriptions are explanations of the reason certain checks are done and what the check is supposed to uncover. This information is numbered and corresponds to the steps on the table. If you are performing a check and wonder why the check is being made or what the check is supposed to find, note the circled number next to the check you are performing. Refer to the information under Test Description that has the same number for an explanation.