Normal Operation
WARNING: This page is about a different car, the 2005 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.
The PCM communicates with the diagnostic tool through controller area network (CAN) circuits 1827 (WH/LG) and 1828 (PK/LG). If one of the CAN circuits become shorted to ground or voltage, or if some but not all termination resistors are lost, communications can continue. Check circuits 1827 (WH/LG) and 1828 (PK/LG) between the PCM C175b 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 1827 (WH/LG) and 1828 (PK/LG), damage to the DLC C251, damage to the PCM C175b, or a problem with the in-line connector.