What Does U1305 Mean?
The Class 2 communication network has detected a short circuit on the serial data bus. This code indicates a specific module or network segment is experiencing a short condition affecting data transmission.
Common Causes
38%
Damaged wiring harness with Class 2 data wire shorted to power or ground
28%
Internally failed control module creating a hard short on the Class 2 network
18%
Trailer wiring or towing accessories improperly connected causing data bus short
16%
Corroded or damaged connector terminals allowing cross-circuit shorting
Diagnostic Steps
1
Step 1: Measure Class 2 data line voltage at DLC while monitoring for proper signal activity (should be 0-7V pulsing)
2
Step 2: Disconnect trailer connections and aftermarket accessories to rule out external causes
3
Step 3: Isolate the short by disconnecting control modules sequentially and monitoring for voltage restoration
4
Step 4: Inspect underbody wiring harnesses for damage from road debris or contact with exhaust components
5
Step 5: Perform resistance testing on the Class 2 circuit with all modules disconnected to locate short location
Estimated Repair Cost
$150 - $1,000
Parts + labor, varies by vehicle and location
The Class 2 communication network has detected a short circuit on the serial data bus. This code indicates a specific module or network segment is experiencing a short condition affecting data transmission.
The most common cause of U1305 (Class 2 Data Link Shorted) is: Damaged wiring harness with Class 2 data wire shorted to power or ground
Typical repair costs for U1305 range from $150 to $1,000, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Network failure may disable airbag systems, ABS, stability control, and other safety-critical systems. Vehicle may not start or may enter limp mode.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U1305 to identify the root cause.
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Quick Info
Category
Network
System
Network Communications
Difficulty
Type
Manufacturer
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