U1116: PCM Lost SCP Bus Communication with BMS
The U1116 code indicates that the Powertrain Control Module (PCM) has detected invalid data or a loss of communication on the Standard Corporate Protocol (SCP) J1850 VPW bus from the Battery Monitoring Sensor (BMS) or the Smart Charge electrical energy management system. This fault prevents the PCM from properly managing the alternator charging strategy and battery state of charge, leading to potential charging system issues.
1. Commonly Affected Makes
2. Most Common Causes
- Faulty or disconnected Battery Monitoring Sensor (BMS)
- Open or short circuit in the SCP bus wiring (typically orange/black and yellow/black wires)
- Internal PCM failure in the SCP communication driver
- Bad battery: sulfated, loose terminals, or excessive corrosion
- Alternator with defective internal regulator (Smart Charge system)
3. Symptoms You Will Notice
- Battery warning light illuminated on the dashboard
- Erratic charging system behavior or battery not charging properly
4. Step-by-Step Diagnosis
Scan for additional codes and verify U1116 is present
Inspect battery condition, terminals, and connections for corrosion or looseness
Check BMS connector and wiring for damage or disconnection
Test SCP bus wiring for continuity, shorts, and proper voltage
If wiring is okay, suspect faulty BMS or PCM; perform manufacturer-specific tests
5. Frequently Asked Questions
Is it safe to drive?▼
You can usually drive short distances, but the battery may not charge correctly, leading to a dead battery or stalling. It's best to diagnose and repair promptly.
How much does it cost to fix?▼
Repair costs range from $100 for a loose connection or terminal cleaning to $500+ for a new BMS sensor or PCM replacement, depending on the vehicle.