Diagnostic Strategies

The following are some guidelines in using the Test Procedures:

1. Start from the beginning of the catagory you are using. Starting from any other point will give you incorrect results.
2. Always perform the diagnostic sequence in each catagory to determine what test is to be performed.
3. Tests are made up of many steps. Only perform the steps which are required. Performing all steps will give incorrect results.
4. Some steps within a test have reminders. These are to inform you that previous instructions are still required.
5. At the end of each test reconnect all wires and hoses, turn engine off if required, and reinstall any components that were removed for testing.
6. The vehicle being tested must have a fully charged battery.
7. To perform the cold test, the engine must not be started for at least 7 hours.
8. To perform the warm test, the engine must be at normal operating temperature.
9. When checking for voltage or continuity at the logic module connectors, use the back (wire side) of the connector not the front (terminal side). Probing the front will damage the female terminals and cause intermittents and failures due to damaged terminals.
10. Use extreme care when making electrical tests and when disconnecting and re-connecting connectors to prevent accidental grounding, shorting or energizing terminals which are connected to the logic module. Such mistakes can possibly damage the logic module and also can cause a second fault that could make diagnosing the original problem more difficult.
11. Under no circumstance should voltage be checked unless specificially instructed by the test procedure.
12. If the procedure requires you to crank the engine with the coil wire disconnected, make sure that it is grounded or held a quarter inch away from ground to allow sparking. Failure to do this will damage the [1][2]power module.
13. Avoid long checks for fuel flow from the injector to prevent flooding or hydrostatic damage to the engine.
14. Remember, this is a pressurized fuel supply system. After testing make sure all fittings are restored and torqued before starting the engine. Once the engine is started. Check for leaks at all lines that were disconnected.
15. Under no circumstances should a test light be used in place of a voltmeter.
16. If more than one fault code appears review the test indication column for multiple code combinations. If one cannot be found then handle each fault code as a separate failure.
17. Some tests require the use of a digital or analog voltmeter. Make sure you use the correct one or you may see incorrect results. If a test does not specify the type of voltmeter then either one may be used.