U1341 SCP Bus Invalid Vehicle Speed Data
The U1341 code indicates that a control module (such as the PCM, ABS module, or instrument cluster) has detected invalid or missing vehicle speed data on the SCP (Standard Corporate Protocol) J1850 communication bus. This Ford-developed network operates at 41.6 kbps and was used in Ford, Lincoln, and Mercury vehicles before CAN bus became standard. The vehicle speed signal is critical for transmission operation, cruise control, ABS, and speedometer display. When data is corrupted, incomplete, or not received within the expected time, the code is set.
1. Commonly Affected Makes
2. Most Common Causes
- Faulty PCM that generates the speed signal
- ABS module internal failure in speed data generation or transmission
- Defective or damaged vehicle speed sensor (VSS)
- Open or short circuit in SCP bus wiring (SCP+ and SCP- circuits)
- Incorrect or missing SCP bus termination resistor
- Instrument cluster internal data processing failure
- Corroded or loose connections in SCP bus connectors
- Electromagnetic interference affecting SCP signal integrity
- Faulty internal software in one of the SCP network modules
3. Symptoms You Will Notice
- Speedometer inoperative or erratic
- Transmission shifting issues (harsh or delayed shifts)
- Cruise control inoperative
- ABS warning light illuminated
- Check Engine Light on
4. Step-by-Step Diagnosis
Scan all modules for related codes and note which modules report U1341
Inspect SCP bus wiring and connectors for damage, corrosion, or loose pins
Check SCP bus termination resistor (typically 120 ohms) at the ends of the bus
Test vehicle speed sensor (VSS) output and wiring
Monitor SCP bus traffic with a scope or scan tool to verify speed data integrity
Perform module communication tests to isolate the faulty module
5. Frequently Asked Questions
Is it safe to drive?▼
The vehicle may be driven short distances, but symptoms like erratic transmission shifting or inoperative ABS can compromise safety. It is recommended to diagnose and repair promptly.
How much does it cost to fix?▼
Repair costs vary widely: from $50-$200 for a VSS replacement to $500-$1500 for module replacement or wiring repairs, plus diagnostic fees.