Diagnostic Notes

DIAGNOSTIC NOTES
Before using this section you should have reviewed Checking the Basics and performed the On-Board Diagnostics procedures and made any necessary repairs, as directed by the On-Board Diagnostics system.

^ Several of the following symptom procedures call for a careful visual/physical check. This step is very important. It can lead to correcting a problem without further checks and can save valuable time.
^ Certain basic faults can be undetectable by the self-diagnostic system and in some cases can actually interfere with the self-checking and fault memory operation. Low battery voltage, for example, can cause erroneous faults to set in control unit fault memories or can cause a system to go into "limp home mode" or open loop operation without setting a fault in memory. On the other hand, system fault memories are cleared whenever the control unit or the battery is disconnected. Therefore, all fault memories should be read prior to any vehicle power interruption or troubleshooting.

DIAGNOSTIC CHARTS
The diagnostic charts contain groups of possible causes for each symptom. These procedures are not necessarily described in the order in which they should be performed. Proceed in a logical order, easiest to check or most likely cause first.