Test J: The Electronic Automatic Temperature Control (EATC) Module Does Not Respond to The Diagnostic Tool
PINPOINT TEST J: THE ELECTRONIC AUTOMATIC TEMPERATURE CONTROL (EATC) MODULE DOES NOT RESPOND TO THE DIAGNOSTIC TOOLJ1-J2:
J2-J3:
Normal Operation
Under normal operation the EATC module communicates with the diagnostic tool through the controller area network (CAN) circuits 3125 (RD/YE) and 3126 (TN/YE). If one of the bus wires becomes shorted to ground or voltage, or if some but not all termination resistors are lost, communications can continue. Check circuits 3125 (RD/YE) and 3126 (TN/YE) between the EATC module C228b 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 circuit 3125 (RD/YE) and 3126 (TN/YE), damage to the DLC C251, or damage to the EATC module C228b.
Possible Causes
- circuit 3125 (RD/YE) open
- circuit 3126 (TN/YE) open
- DLC C251
- EATC module
- EATC module C228b