Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC U1300: Class 2 Circuit (Short To Ground): Description
Body Control Module (BCM) interfaces with other vehicle systems using class 2 serial data line. DTC U1300 will set when BCM detects a short to ground in class 2 serial data line circuit No. 1132 (Purple wire). No driver warning message will be displayed.
DTC U1300 will clear when BCM does not detect short to ground in circuit No. 1132 (Purple wire) and BCM monitors its own transmitted message. If conditions for malfunction no longer exist, history DTC will clear after 100 consecutive ignition cycles. DTC U1300 will also clear when scan tool is used to clear codes.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.