SCP Bus Communication Failure
Diagnostic trouble code U1070 indicates a failure in the SCP (Standard Corporate Protocol) communication bus, which is Ford's proprietary implementation of the SAE J1850 protocol operating at 41.6 kbps via pulse-width modulation on DLC pins 2 and 10. This code sets when a receiving module (such as the PCM, ICM, or instrument cluster) detects that expected engine data messages on the SCP bus are missing, corrupted, or out of range, preventing proper serial communication between control modules.
1. Commonly Affected Makes
2. Most Common Causes
- Faulty PCM that interrupts SCP transmission
- Open or short circuit in the SCP bus wiring (SCP+ and SCP- circuits)
- SCP bus terminal resistance out of specification (should be approximately 120 ohms)
- Defective engine sensor module with faulty SCP data output
- Electromagnetic interference corrupting bus signals
- Corroded or loose DLC connector pins 2 or 10
- Faulty instrument cluster or module expecting engine data
3. Symptoms You Will Notice
- Check Engine Light illuminated
- Erratic gauge readings or no communication with scan tool
4. Step-by-Step Diagnosis
Verify DLC connector pins 2 and 10 for damage or corrosion
Measure resistance between SCP+ and SCP- at the DLC; should be about 60 ohms (two 120-ohm terminators in parallel)
Check for voltage on SCP+ (should pulse around 0-5V) and SCP- (around 5V) with a scope
Inspect SCP bus wiring for opens, shorts, or chafing
Test each module on the bus by disconnecting one at a time and monitoring resistance/communication
If wiring and resistance are good, suspect a faulty PCM or other module
5. Frequently Asked Questions
Is it safe to drive?▼
The vehicle may still be drivable, but you may experience performance issues or lack of critical data. It's recommended to diagnose and repair promptly to avoid further problems.
How much does it cost to fix?▼
Costs vary widely depending on the root cause: from $50-$150 for a wiring repair to $500-$1000+ for a PCM replacement. Diagnostic fees typically range $100-$200.