OBD2 Code U1150: SCP Bus Communication Fault
The U1150 code indicates that a control module has detected invalid or missing data on the SCP (J1850) communication bus, specifically related to the audible warnings system. This protocol is used primarily by Ford Motor Company in older models. The code sets when the receiving module does not get expected information from the module managing audible warnings, or when the data received is corrupt, out of range, or not in the correct format. This can affect functions like seatbelt chime, door ajar alerts, or navigation system sounds.
1. Commonly Affected Makes
2. Most Common Causes
- Faulty audible warnings control module (chime module or instrument cluster)
- Open or short circuit in the SCP (J1850) bus wiring between modules
- SCP bus terminal resistance out of specification (degraded terminators)
- Faulty instrument cluster that integrates chime functions
- Electromagnetic interference corrupting bus signals
- Defective control module transmitting erroneous data on the bus
- Corroded or loose connectors in the communication bus harness
- Low battery voltage or charging system issue affecting module communication
3. Symptoms You Will Notice
- No audible warnings (seatbelt chime, door ajar, headlights on)
- Intermittent or incorrect chime sounds
- Other communication-related issues on the same bus
4. Step-by-Step Diagnosis
Scan for all stored codes and freeze frame data
Inspect SCP bus wiring and connectors for damage, corrosion, or looseness
Check battery voltage and charging system (should be 12.6V+ engine off, 13.5-14.5V running)
Measure SCP bus resistance at the DLC (should be ~60 ohms with two terminators)
Test the audible warnings module (chime module or cluster) per service manual
Check for TSBs related to U1150 for the specific vehicle
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, the vehicle is generally safe to drive, but you may lose audible warnings like seatbelt chime or door ajar alerts. Have it diagnosed soon to prevent further communication issues.
How much does it cost to fix?▼
Diagnosis typically costs $100-$150. Repairs range from $50 for a loose connector to $500+ for a new instrument cluster or chime module, plus labor.