Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

Or, hide this message: temporarily or permanently

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