Test D: The Electronic Automatic Temperature Control (EATC) Module Does Not Respond To The Diagnostic Tool

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

D1-D2:

D2-D3:

Normal Operation
The EATC module communicates with the diagnostic tool through the standard corporate protocol (SCP) communication network, circuits 914 (TN/OG) and 915 (PK/LB). Check the SCP circuits 914 (TN/OG) and 915 (PK/LB) between the EATC module C228a 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 the SCP network circuits, damage to the DLC C251, the EATC module C228a, or a problem in the in-line connectors.

Possible Causes
- SCP data plus circuit 914 (TN/OG) open
- SCP data minus circuit 915 (PK/LB) open
- EATC C228a
- EATC