Test J: The Dual Automatic Temperature Control (DATC) Module Does Not Respond To The Diagnostic Tool

PINPOINT TEST J: THE DUAL AUTOMATIC TEMPERATURE CONTROL (DATC) MODULE DOES NOT RESPOND TO THE DIAGNOSTIC TOOL

J1:

J2-J3:

Normal Operation
The DATC module communicates with the diagnostic tool through the medium speed controller area network (CAN), circuits 2180 (WH/BK) and 2181 (BK/YE). The medium speed CAN is not designed to operate under single point fault conditions. If either circuit is shorted to voltage or the high speed CAN data plus is shorted to ground, module-to-module and module-to-tester communication is not possible. If the medium speed CAN data minus is shorted to ground or an open exists on either bus line, module-to-module and module-to-tester communication is marginal at best. The medium speed CAN bus may remain operational when one of the two termination resistors are not present. The total resistance values must not be more than 5 ohms. If the resistance is more than 5 ohms there is an open in one of the medium speed CAN circuits, damage to the data link connector (DLC) C251, damage to the DATC module connector, or damage to an in-line connector.

Possible Causes
- medium speed CAN circuit 2180 (WH/BK) or 2181 (BK/YE) open
- DATC module C228a
- DATC module