What Does U1300 Mean?
The Class 2 data link network has detected a short circuit condition. This prevents proper communication between control modules on the Class 2 serial data bus.
Common Causes
40%
Shorted Class 2 data circuit wire to ground or power, often from chafed insulation or pinched wiring
25%
Damaged or internally shorted control module pulling the data line voltage out of range
20%
Aftermarket accessories or trailer wiring improperly connected to Class 2 circuit
15%
Corroded or damaged connector causing intermittent short to adjacent circuits
Diagnostic Steps
1
Step 1: Measure voltage on the Class 2 data circuit (typically at DLC pin 2) with key on; should be approximately 5-7 volts pulsing
2
Step 2: Disconnect modules one at a time starting with most recently serviced or aftermarket equipment to isolate the short
3
Step 3: Inspect wiring harnesses for visible damage, particularly where harnesses route near sharp edges or moving components
4
Step 4: Use a digital multimeter to check for shorts to ground or power on the Class 2 circuit with all modules disconnected
5
Step 5: Verify proper termination and check for moisture intrusion in connectors along the data bus
Estimated Repair Cost
$150 - $900
Parts + labor, varies by vehicle and location
The Class 2 data link network has detected a short circuit condition. This prevents proper communication between control modules on the Class 2 serial data bus.
The most common cause of U1300 (Class 2 Data Link Shorted) is: Shorted Class 2 data circuit wire to ground or power, often from chafed insulation or pinched wiring
Typical repair costs for U1300 range from $150 to $900, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Loss of communication may disable safety systems including ABS, airbag systems, and stability control. Vehicle may enter reduced power mode or fail to start.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U1300 to identify the root cause.
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Quick Info
Category
Network
System
Network Communications
Difficulty
Type
Manufacturer
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