Limitations

Terminal "E" or "M" of the underdash ALDL connector allows access to a variety of computer sensor circuit information, using several types of aftermarket scanners. Understanding the function of the circuit can be useful in obtaining information that might otherwise prove time consuming or impossible to obtain using other test procedures.

Serial Data access can be useful in obtaining information regarding intermittent malfunctions, since the tool can be installed and the vehicle is monitored while operating under the conditions where the malfunction may occur. If the malfunctions seem to be related to specific functions that are monitored by the access tool, the system can be checked in the applicable positions, under the actual operating conditions. If the malfunction is not related to any specific area, the system can be monitored in all tester positions for a period of time, or under a group of operating conditions. This allows the technician to observe the system and monitor changes in tester readings that may indicate a system malfunction.

For complete information regarding the operation of Scan tools, refer to specific scan tool instructions.