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Randall C
Randall C, ASE Master Tech
Category: Chevy
Satisfied Customers: 12787
Experience:  ASE Master, L1, 32 years, Diagnostic / Electrical Specialist
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What is the meaning of the trouble code- U1301 What is the

Resolved Question:

What is the meaning of the trouble code- U1301? What is the Class 2 device? Can this cause intermittent loss of ignition?
Submitted: 7 years ago.
Category: Chevy
Expert:  Randall C replied 7 years ago.
hello, there is a delay getting info on my end. What is the year, model, engine of the vehicle?
Customer: replied 7 years ago.

The Year is 2001. The model is a Silverado 2500 HD. The Engine is an 8.1 Vortec

Expert:  Randall C replied 7 years ago.

Thanks, XXXXX XXXXX finally come through :) Let me check a couple things. back shortly

 

Expert:  Randall C replied 7 years ago.

The complicated version is below. basically you are losing communication between computers. this is very difficult to trace and requires a scanner and hope it is happening at the time. i wish i could give you a 100% reason/answer but can not. this type of code really does mean a tech needs to scan engine and follow many wires.

 

CIRCUIT DESCRIPTION
Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. In addition to this, Node Alive messages are transmitted by each module on the class 2 serial data circuit about once every two seconds . When the module detects no messages and a high voltage on the Class 2 serial data link for approximately three seconds , U1301 is set and the setting of all other class 2 serial communication DTCs is inhibited.

CONDITIONS FOR RUNNING THE DTC

  • Voltage supplied to the module is in the normal operating voltage range.
  • The vehicle power mode requires serial data communication to occur.

CONDITIONS FOR SETTING THE DTC

  • No valid class 2 messages are detected on the class 2 serial data circuit.
  • The voltage level detected on the class 2 serial data circuit is high.
  • The above conditions are met for approximately 3 seconds .

ACTION TAKEN WHEN THE DTC SETS

  • The module inhibits the setting of all other class 2 DTCs.
  • The module uses default values for all parameters received on the class 2 serial data circuit.

CONDITIONS FOR CLEARING THE DTC

  • A current U1301 will clear when a valid class 2 message is detected on the class 2 serial data circuit or at the end of the current ignition cycle.
  • A history U1301 will clear upon receipt of a scan tool Clear DTCs command.

DIAGNOSTIC AIDS

  • This DTC cannot be retrieved with a current status. Diagnosis of a current U1301 is accomplished via the symptom, Scan Tool Does Not Communicate with a Class 2 Device. Refer to Scan Tool Does Not Communicate with Class 2 Device. See: Scan Tool Testing and Procedures
  • An intermittent condition is likely to be caused by a short to voltage on the class 2 serial data circuit. Use the Scan Tool Does Not Communicate with a Class 2 Device procedure in order to isolate an intermittent condition. Refer to Scan Tool Does Not Communicate with Class 2 Device. See: Scan Tool Testing and Procedures

 

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