Table Layout

When diagnosing the Catera engine, you will almost certainly need to use the diagnostic procedures here. These diagnostic procedures are mostly in the form of tables. In the supporting text for each diagnostic table is a circuit diagram (in most cases), a circuit description. the conditions under which the ECM will run the diagnostic, the conditions that will cause the DTC to set, a description of the action taken (MIL operation. default actions), any diagnostic aids and any test descriptions which elaborate on the certain steps in the table. Reading the supporting text will help you to understand the DTC or the condition and what the trouble chart is trying to accomplish. The following are definitions of the facing page information:

Circuit Diagram
The circuit diagram will show the circuits and the components that are involved in setting the DTC. You may use this diagram as a reference when the circuit checks are required in the table. If more detailed circuit information is required. refer to Diagrams at the component or system level for a more detail.

Circuit Description
The circuit description explains the operation of the system and/or the affected circuits.

Conditions For Running the DTC
The Conditions For Running the DTC are the conditions that must be met before the ECM will test a particular system or circuit.

Conditions For Setting the DTC
The Conditions For Setting the DTC are the conditions that cause the diagnostic to fail. These conditions are checked only after the test conditions (described above) have been met.

Action Taken When The DTC Sets
A DTC may or may not illuminate the MIL, depending on the DTC type (refer to DTC Type). The ECM may also use a default strategy in order to compensate for the problem. These actions serve the following purpose:
- To preserve the driveability of the vehicle
- To prevent the failure from causing any damage to the vehicle

Diagnostic Aids
Most trouble charts 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 the Freeze Frame data or the 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 will explain what to look for and which direction to head in looking for an intermittent failure.

Test Description
The Test Descriptions are further explanations of why certain checks are done and what the check is supposed to uncover. The notes are numbered and correspond to the steps on the trouble chart. If you are performing a check and wonder why the check is being made or what the check is supposed to find. refer to the note under Test Description that has the same number for an explanation. Note: not all of the steps are supported.

Diagnostic Table
The diagnostic tables are an organized and systematic approach to diagnosing a DTC. The diagnostic table consists of five separate columns: the step number, the action, the value, yes, and no. The step number indicates which step is being performed. The action column contains all of the necessary information about how to perform a certain test. The last sentence in each action block will always be a question. You can only answer the question yes or no. The answer to the question will dictate which column you will go to next, yes or no. The yes or no answer to each test will lead you to the next step to be performed or to a particular action to take. Most of the boxes will have a Go to Step X statement. If a yes or no block does not have a Go to Step X statement, the text inside will be the last step taken on the trouble chart because this step will either be a solution or a Fault Not Present condition.
Always begin with step 1 at the top of the diagnostic table unless there is a note or caution above the diagnostic table. (Some tables will have notes at the top to warn of possible damaging conditions or existing conditions that may hamper the diagnosis.) Never skip steps or jump ahead in the diagnostic table. Always go where the Yes or No box instructs you to go. Taking short cuts often leads to misdiagnosis. When a problem is found. make the necessary repairs and then verify the repair.

Verify Repair
The last few steps of the diagnostic table are intended to verify any repairs that have been made. This is one of the places that you will be instructed to clear the DTCs. Then the vehicle should be run within the Conditions For Running the DTC. and then rechecked for the DTCs. Additional DTCs that may have been set should have been written down during the OBD System Check. At this point. if the DTC did not re-set. continue on to the next DTC, if any multiple DTCs were stored.