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Shawn, Auto Service Technician
Category: Ford
Satisfied Customers: 3756
Experience:  16 years experience Ford,Nissan and Honda dealership in all areas
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How do I fix a U1900 code?

Resolved Question:

How do I fix a U1900 code?

Submitted: 6 years ago.
Category: Ford
Expert:  Shawn replied 6 years ago.

The most common cause of the trouble code U1900 is a possible defective instrument cluster or an issue with the trailer brake controller, the other possibilities are below, if you need I can send test procedures in order to determine the cause.

Normal Operation

The high speed CAN (Controller Area Network) has an unshielded twisted pair cable, circuits 1908 (WH) and 1909 (BK). The anti-lock brake system (ABS) module, the instrument cluster, the power train control module (PCM) and the trailer brake controller are all on the CAN. The total resistance values from the module to the data link connector (DLC) must not be more than 5 ohms. If the resistance is more than 5 ohms there is an open in one of the CAN circuits, damage to the DLC C251, damage to one of the communications network module connectors, or damage to an in-line connector.

Possible Causes

  • CAN circuit 1908 (WH) open, short to ground, or short to voltage.
  • CAN circuit 1909 (BK) open, short to ground, or short to voltage.
  • DLC C251
  • ABS module
  • ABS module C135
  • instrument cluster
  • instrument cluster C220b
  • PCM
  • PCM C175b or C1381b
  • trailer brake controller
  • trailer brake controller C2142b

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