Normal Operation
WARNING: This page is about a different car, the 2004 Mercury Mountaineer and 2004 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.
The PCM 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 PCM C175b 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 3125 (RD/YE) and 3126 (TN/YE), damage to the DLC C251, damage to the PCM C175b, or a problem in the in-line connectors.