Scan Tool Testing and Procedures

The tool manufacturers have developed "Scan" tools to interface with the diesel electronic control system, through the ALDL. It supplies a visual reading of most inputs to the ECM and some outputs. Review the tool instruction manual to understand its operation and limitations.

When the tool is connected to the ALDL and cigarette/cigar lighter connector or 12 volts, there should be a visual instruction displayed. If there is no display, or tool reads "No DATA" or "No ALDL," refer to "ECM Check" diagnosis and tool instructions to be sure that 6.2L diesel engine is available in the tool.

With the tool in the code position, the display window will indicate any code stored in the ECM memory. Referring to the applicable code chart, the tool will "Scan" an input to determine if a specific circuit is operating properly.