U1247 SCP Bus Invalid or Missing Primary ID Data
The U1247 code indicates that a control module on the SCP (Standard Corporate Protocol) J1850 VPW network has detected invalid or missing data for a specific Primary ID. This means a transmitting node is either not sending its required periodic message, or the received data fails integrity checks (CRC, length, format), preventing synchronization of shared functions between modules.
1. Commonly Affected Makes
2. Most Common Causes
- Failed or unpowered module responsible for the Primary ID
- Open or short circuit in the SCP bus (+/-) wiring
- Damaged or missing SCP bus termination resistors
- Internal software error in the receiving or transmitting module
- Excessive electromagnetic interference (EMI) on the communication harness
3. Symptoms You Will Notice
- Check Engine Light or other warning lights illuminated
- Malfunction of systems that rely on the missing data (e.g., transmission, ABS, instrument cluster)
4. Step-by-Step Diagnosis
Scan all modules for related codes and check network communication
Inspect SCP bus wiring for opens, shorts, or corrosion
Measure bus termination resistance (should be ~120 ohms total)
Test power and ground at the suspected transmitting module
If wiring and power are OK, replace the module that is not communicating
5. Frequently Asked Questions
Is it safe to drive?▼
The vehicle may still be drivable, but some systems may not function properly. It is recommended to diagnose and repair the issue soon to avoid further problems.
How much does it cost to fix?▼
Diagnosis typically costs $100-$150. Repair costs vary widely: wiring repairs $100-$300, module replacement $200-$800+ depending on the module.