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Test I

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


Test I1-I2:






Test I2-I3:






Normal Operation
Under normal operation the EATC module communicates with the diagnostic tool through the SCP communications network circuits 914 (TN/OG) and 915 (PK/LB). 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 914 (TN/OG) and 915 (PK/LB) between the EATC module C228b and the data link connector (DLC) C251. Total resistance values must not be more than 5 ohms. If the resistance is more than 5 ohms there is an open in circuit 914 (TN/OG) or 915 (PK/LB), damage to the DLC C251, or damage to the EATC module C228b.

Possible Causes
- circuits 914 (TN/OG) or 915 (PK/LB) shorted to ground or open
- C228b
- DLC C251
- EATC module
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