Quick Answer
C0691 means: DTC C0691 indicates a communication failure between the vehicle's control modules.
Can I drive with C0691? Address immediately to avoid further electrical issues.
Common Questions
What does C0691 mean and how does it affect my car?
C0691 indicates a communication failure between vehicle control modules. This can lead to malfunctioning electronic components, dashboard issues, and even safety concerns if left unresolved.
What are the most common causes of C0691 and how much does it cost to fix?
Common causes include damaged wiring (60% likelihood), faulty BCM (20% likelihood), with repair costs ranging from $150 to $600 based on the issue.
Can I drive my car with C0691 or should I stop immediately?
It is advisable to address C0691 as soon as possible. Driving with this code can lead to further electrical malfunctions that may compromise safety.
How can I diagnose C0691 myself using GeekOBD APP?
Use GeekOBD APP to scan for trouble codes, check freeze frame data, and monitor live data to identify any irregularities in system performance.
What vehicles are most commonly affected by C0691?
C0691 commonly affects Chevrolet and GMC models from 2008 to 2018, including Silverado and Sierra trucks, and Equinox crossovers.
How can I prevent C0691 from happening again?
Regular maintenance, including inspecting wiring and connections, can help prevent C0691. Consider using protective measures against corrosion and wear.
What is C0691?
DTC C0691 refers to a specific issue related to the communication between the vehicle's control modules, particularly in systems such as the body control module (BCM) and the instrument panel cluster (IPC). This code typically appears in models from manufacturers such as Chevrolet and GMC, especially those produced between 2008 and 2018. When C0691 is triggered, it indicates that there is a problem with the data communication line. This can lead to various malfunctions, such as the failure of the dashboard lights, issues with power windows, or problems with the vehicle's locks. In practice, this means that you might experience inconsistent behavior from electronic components that rely on this communication. Ignoring this code can lead to further complications, including more extensive electrical issues and potentially even safety hazards if critical systems fail. If you see the C0691 code on your OBD2 scanner, it's essential to address it promptly to ensure the continued reliability and safety of your vehicle.
System: C - Chassis (ABS, Steering, Suspension)
Symptoms
Common symptoms when C0691 is present:
- The check engine light may illuminate and remain on, indicating a need for diagnostics.
- You might experience erratic behavior from dashboard gauges, such as speedometer fluctuations or unresponsive indicators during operation.
- Power accessories like windows and locks may not function properly, leading to inconvenience and potential safety concerns.
- The vehicle's lighting system may act inconsistently, with some lights not activating or turning off unexpectedly.
- In some cases, the vehicle may also exhibit intermittent starting issues, making it unreliable.
Possible Causes
Most common causes of C0691 (ordered by frequency):
- The most common cause of C0691 is a faulty or damaged wiring harness, which occurs in about 60% of cases. This can stem from wear and tear or exposure to harsh environmental conditions.
- Another prevalent cause is a malfunctioning body control module (BCM), typically accounting for around 20% of occurrences. A BCM issue can arise from software glitches or hardware failures.
- Corrosion at connector terminals can lead to communication failures, especially in older vehicles. Regular inspections and maintenance can help prevent this issue.
- Less commonly, a bad instrument panel cluster can trigger this code. This is particularly serious as it affects vital information displayed to the driver.
- Rarely, issues with the vehicle's main computer (ECM/PCM) can result in a C0691 code, which may require extensive diagnostic procedures to resolve.
C0691 Repair Costs
Cost Breakdown by Repair Type
Wiring Harness Replacement
Replacing damaged wiring can resolve communication issues and restore functionality.
- Total: $150 - $300
- Success rate: 90%
Body Control Module Repair/Replacement
Repairing or replacing the BCM to ensure proper communication between systems.
- Total: $300 - $600
- Success rate: 85%
Money-Saving Tips for C0691
- Start with the most common and least expensive repairs first
- Use GeekOBD APP to confirm diagnosis before replacing expensive parts
- Consider preventive maintenance to avoid future occurrences
- Compare prices for OEM vs aftermarket parts based on your needs
- Address the issue promptly to prevent more expensive secondary damage
Diagnostic Steps
Professional C0691 Diagnosis Process
Follow these systematic steps to accurately diagnose C0691. Each step builds on the previous one to ensure accurate diagnosis.
Step 1: Step 1: Initial visual inspection - Begin by checking for obvious signs of damage such as frayed wiring, loose connections, or corrosion (5-10 minutes)
Step 1: Initial visual inspection - Begin by checking for obvious signs of damage such as frayed wiring, loose connections, or corrosion (5-10 minutes).
Step 2: Step 2: Use an OBD2 scanner with GeekOBD APP - Connect your device and retrieve all diagnostic trouble codes along with freeze frame data to understand the context of the fault (10-15 minutes)
Step 2: Use an OBD2 scanner with GeekOBD APP - Connect your device and retrieve all diagnostic trouble codes along with freeze frame data to understand the context of the fault (10-15 minutes).
Step 3: Step 3: Component testing - Utilize a multimeter or specific diagnostic tools to test the affected components, like the BCM and IPC, to identify faults (20-30 minutes)
Step 3: Component testing - Utilize a multimeter or specific diagnostic tools to test the affected components, like the BCM and IPC, to identify faults (20-30 minutes).
Step 4: Step 4: System function test - After any repairs, verify the proper operation of all systems and clear the codes to see if they return (10-15 minutes)
Step 4: System function test - After any repairs, verify the proper operation of all systems and clear the codes to see if they return (10-15 minutes).
Step 5: Step 5: Road test verification - Drive the vehicle under various conditions to confirm that the issue is resolved and the code does not reappear (15-20 minutes)
Step 5: Road test verification - Drive the vehicle under various conditions to confirm that the issue is resolved and the code does not reappear (15-20 minutes).
Important Notes
- Always verify the repair with GeekOBD APP after completing diagnostic steps
- Clear codes and test drive to ensure the problem is resolved
- Address underlying causes to prevent code recurrence
Real Repair Case Studies
Case Study 1: 2015 Chevrolet Silverado C0691 Repair
Vehicle: 2015 Chevrolet Silverado, 85,000 miles
Problem: Customer reported dashboard gauges malfunctioning intermittently.
Diagnosis: Diagnostic scan revealed C0691. Visual inspection showed frayed wiring near the BCM.
Solution: Replaced damaged wiring and secured connections; cleared codes.
Cost: $250 (including parts and labor)
Result: Issue resolved, gauges functioning normally post-repair.
Case Study 2: 2018 GMC Terrain C0691 Communication Failure
Vehicle: 2018 GMC Terrain, 40,000 miles
Problem: Check engine light on, power windows not operating.
Diagnosis: C0691 indicated communication error; BCM tested and confirmed faulty.
Solution: Replaced BCM with new unit; updated software.
Cost: $550 (parts and labor included)
Result: All systems restored to normal operation, no codes returned.