Data Link Connector "Scan Tools"

DATA LINK CONNECTOR "SCAN TOOLS"
The Engine Control Module (ECM) can communicate a variety of information through data link connector terminal "2". This data is transmitted at a high frequency which requires a "Scan tool" for interpretation. There are several "Scan tools" available for reading this information.

With an understanding of the data which the tool displays, and knowledge of the circuits involved, the tool can be very useful in obtaining information which would be more difficult or impossible to obtain with other equipment.

"Scan tools" do not make the use of diagnostic charts unnecessary, nor can they indicate exactly where a problem is in a particular circuit. Trouble Tree Charts incorporate diagnosis procedures using a "Scan tool" where possible and most charts require the use of a "Scan tool" when it is applicable.

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 MIS- DIAGNOSIS AND UNNECESSARY PARTS REPLACEMENT.

ECM's have two (2) modes for transmitting information. The following information will describe the system operation in each of the modes.



DATA LIST (FO)
On engines that can be monitored in the "Open" mode, certain parameters can be observed without changing the engine operating characteristics. The parameters capable of being read vary with engine families. Most "Scan tools" are programmed so that the system will go directly into the data link connector mode if the "Open" mode is not available.