With Manufacturer's Scan Tool

Data Link Connector (DLC):

READING CODES
The recommended method for reading diagnostic trouble code(s) stored in memory is by using diagnostic scan tool plugged into the Data Link Connector (DLC). On some applications, a Vehicle Interface Module (VIM) may be required to communicate with the vehicle. Follow instructions supplied by tool manufacturer.

DATA LINK CONNECTOR
The provision for communicating is the Data Link Connector. It is usually located under the instrument panel and is sometimes covered by a plastic cover labeled "DIAGNOSTIC CONNECTOR." It is used in the assembly plant to receive information in checking that the engine is operating properly before it leaves the plant. The connector can also be used by the service technician to identify stored trouble codes and to read Powertrain Control Module data using a hand held scan tool.

DLC SCAN TOOLS
The system can communicate a variety of information through the Data Link Connector. This data is transmitted at a high frequency which requires a Tech 1 Diagnostic Computer (or equivalent scan tool) for interpretation. There are several scan tools available for reading this information.
With an understanding of the data which the tool displays, and knowledge of the circuits involved, the tool can be very useful in obtaining information which would be more difficult or impossible to obtain with other equipment.
Tech 1 and scan tools do not make the use of diagnostic trouble code charts unnecessary, nor can they indicate exactly where a problem is in a particular circuit. These charts Incorporate diagnosis procedures using a Tech 1 tool where possible and most charts require the use of a Tech 1 when it is applicable.

NOTE: Tech 1 tool that displays faulty data should not be used and the problem should be reported to the manufacturer. The use of a faulty scan tool can result in misdiagnosis and unnecessary parts replacement.


TECH 1 USE WITH INTERMITTENTS
In some scan tool applications, the data update rate makes the tool less effective than a voltmeter, such as when trying to detect an intermittent problem which lasts for a very short time. However, the Tech 1 Scan Tool allows manipulation of wiring harnesses or components under the hood with the engine not running, while observing the Tech 1 Scan Tool readout.

The Tech 1 scan tool can be plugged in and observed while driving the vehicle under the condition when the Malfunction Indicator Lamp (MIL) (Service Engine Soon/Check Engine) turns "ON" momentarily or when the engine driveability is momentarily poor. If the problem seems to be related to certain parameters that can be checked on the Tech 1 scan tool, they should be checked while driving the vehicle. If there does not seem to be any correlation between the problem and any specific circuit, the Tech 1 Scan Tool can be checked on each position, watching for a period of time to see if there is any change in the readings that indicates intermittent operation.

The Tech 1 Scan Tool is also an easy way to compare the operating parameters of a poorly operating engine with those of a known good one. For example, a sensor may shift in value but not set a diagnostic trouble code. Comparing the sensor's readings with those of a known good vehicle may uncover the problem.
The Tech 1 Scan Tool has the ability to save time in diagnosis and revent the replacement of good parts. The key to using the Tech 1 Scan Tool successfully for diagnosis lies in the technician's ability to understand the system being diagnosed as well as an understanding of the Tech 1 Scan Tool operation and limitations. The technician should read the tool manufacturer's operating manual to become familiar with the tool's operation.