Preliminary Procedures

Prior to any hard part diagnosis, various system checks are appropriate.

• Check to see if the "Service Engine Soon" lamp is working. If this lamp fails to light when the ignition is turned on and the engine is not running, the problem could be in the power supply circuits to these systems. The "Self-Diagnostic Check" will bring about the appropriate diagnostic chart.
• Can the "Service Mode" be accessed? If the CRT is not operable, self-diagnostics are not possible. In this case, the "Self-Diagnostic System Check" will bring about the appropriate diagnostic chart.
• Is there a service code displayed? If a trouble code is identified using self-diagnostics, a problem has been detected by the system which can be corrected by following the appropriately numbered fault code. Codes with the prefix "E" are ECM codes. Codes with the prefix "B" are BCM codes.
• Do a visual check of the entire system. Check the suspected wiring and components. Be sure to inspect hoses that are difficult to see beneath the compressor, generator, etc. Inspect all the related wiring for disconnects, burned or chafed spots, pinched wires or contact with sharp edges or hot exhaust manifolds.