Test B: The Electronic Automatic Temperature Control (EATC) Module Does Not Respond to the Diagnostic Tool

PINPOINT TEST B: THE ELECTRONIC AUTOMATIC TEMPERATURE CONTROL (EATC) MODULE DOES NOT RESPOND TO THE DIAGNOSTIC TOOL

B1-B3:

Normal Operation
The EATC module communicates with the diagnostic tool through the medium speed controller area network (CAN), circuits 1827 (WH/LG) and 1828 (PK/LG). Check circuits 1827 (WH/LG) and 1828 (PK/LG) between the EATC module C228 and the data link connector (DLC) C251. 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 DLC C251, damage to the EATC module C228, or a problem in an in-line connector.

Possible Causes
- medium speed CAN circuit 1827 (WH/LG) open
- medium speed CAN circuit 1828 (PK/LG) open
- EATC module
- EATC module C228