Scan Tool Usage

NOTE: Before connecting scan tool to vehicle, diagnostic system should be checked to determine if system is operating properly and if information received will be accurate. This is done by performing ON-BOARD DIAGNOSTIC SYSTEM CHECK. If vehicle does not pass diagnostic check, information received may be invalid.

Scan tool is a specialized tool which, when plugged into DLC, can be used to diagnose on-board computer control systems by providing instant access to circuit voltage information without need to crawl under dash or hood to backprobe sensors and connectors.

Scan tool cuts down diagnostic time dramatically by furnishing input data (voltage signals) which can be compared to specification parameters. See SCAN TOOL CCM DATA . They may also furnish information on output device (solenoids and motors) status. However, status parameters only indicate output signals have been sent to devices by control module; they do not indicate whether devices have responded properly to signal. Verify proper response at output device using a voltmeter or test light.

A problem may exist even if trouble codes are not present. About 80 percent of driveability problems occur without trouble codes. Sensors that are out of calibration will not set a trouble code but will cause driveability problems.

Using a scan tool is the easiest method of checking sensor specifications and other data parameters. Tool is also useful in finding intermittent wiring problems by wiggling wiring harnesses and connections (key on, engine off) while observing data parameters. See SCAN TOOL CCM DATA .

NOTE: If erroneous voltage signals are suspected, verify tool information using a digital voltmeter and wiring schematic. If non-existent codes are displayed, DO NOT use scan tool for diagnosis. Contact tool manufacturer for additional information.