Description and Use

Data Link Connectors (DLC):

DATA LINK CONNECTOR SCAN TOOLS
The control module will communicate a variety of information through the underdash DLC connector terminal "M". This data is transmitted at a high frequency which requires a TECH 1 diagnostic scan tool for interpretation. There are several other scan tools available for displaying this same information. Refer to manufacturers instructions for diagnostic test and code extraction. The information contained within this section is described for use of a TECH 1 scan tool.
The TECH 1 scan tool can be very useful in obtaining information which would be difficult or impossible to obtain with other equipment.
TECH 1 and other scan tools do not make the use of diagnostic charts unnecessary, or indicate exactly where a problem is in a particular circuit.

NOTE: A special 12 to 16 pin harness adapter is necessary for some applications. This adapter is available for the TECH 1 scan tool as harness adapter part #3000053.

SCAN TOOL USE WITH INTERMITTENTS
In some scan tool applications, the data update rate makes the scan tool less effective than a voltmeter 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 operating, while observing the readouts.
The TECH 1 scan tool can be plugged in with data displayed while driving the vehicle when the malfunction indicator lamp turns "ON" momentarily or when engine driveability is momentarily poor
If the problem is related to certain parameters that can be checked by the TECH 1 scan tool, this should be done 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 display each parameter, for any period of time to observe any change in the readings which might indicate an intermittent operation.
The TECH 1 scan tool is used 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 locate the fault.
The TECH 1 scan tool has the ability to save time in diagnosis and prevent the replacement of good parts. The key to using the TECH 1 scan tool successfully for diagnosis is in the technician's ability to understand the system he is trying to diagnose, as well as an understanding of the TECH 1 scan tool's operation and limitations. The technician should use the tool manufacturer's operating manual to become familiar with the tool's operation.

NOTE: A scan 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.

DATA DEFINITIONS
The TECH 1 scan tool data definitions describe the tools display for the different selector positions, including what units of measurement are being displayed, and the range of possible values for each display. This information will assist in tracking down emission or driveablity problems, since the displays can be viewed while the vehicle is being driven. For additional information, refer to the Diagnostic System Check.
Testing and Inspection

TYPICAL SCAN DATA VALUES
This is a list of signals that can be monitored by a scan tool, describing units of measurement along with the specified normal operating range for each displayed value. For additional information, refer to the Typical Scan Data Values. Scan Tool Data List