With Generic Scan Tool

Data Link Connectors (DLC)s:

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.

DLC SCAN TOOL
The underdash Data Link Connector connector allows access to a variety of computer sensor circuit data. This data is transmitted at a high frequency which requires a Tech 1 Diagnostic Computer (scan) tool (or equivalent) for interpretation. Understanding the function of the scan tool can be useful in obtaining information that might otherwise prove time consuming or impossible to obtain using other test methods.

The Tech 1 scan tool does not make the use of diagnostic trouble code charts unnecessary, nor can it indicate exactly where a problem is in a particular circuit. These charts incorporate diagnosis procedures using a Tech 1 scan tool where possible and most charts require the use of a Tech 1 when it is applicable.

CAUTION: A 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 SCAN TOOL 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 allows manipulation of wiring harnesses or components under the hood with the engine not running, while observing the Tech 1 readout.

The Tech 1 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, 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 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 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 has the ability to save time in diagnosis and revent the replacement of good parts. The key to using the Tech 1 successfully for diagnosis lies in the technician's ability to understand the system being diagnosed as well as an understanding of the Tech 1 operation and limitations. The technician should read the tool manufacturer's operating manual to become familiar with the tool's operation.