P0691 2018 Chevrolet Silverado Code - Cooling Fan Speed Output Circuit Low Voltage
Quick Answer
The engine cooling fan system is composed of 2 electric cooling fans, fan motors, and 2 control modules. Common causes include Faulty Cooling Fan Control Module, Cooling Fan Control Module harness is open or shorted, Cooling Fan Control Module circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- P0691 2018 Chevrolet Silverado indicates Cooling Fan Speed Output Circuit Low Voltage.
- Common causes
- Common causes include Faulty Cooling Fan Control Module, Cooling Fan Control Module harness is open or shorted, Cooling Fan Control Module circuit poor electrical connection.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code P0691 2018 Chevrolet Silverado Description
The cooling fan speed is affected by many different conditions and the ECM will adjust the duty cycle from 0 - 100 percent based on cooling system requirements. The scan tool output control is only capable of operating the cooling fan increments, between 10 - 90 percent. 90 percent is considered high-speed fan. When multiple cooling fan speed requests are received, the ECM operates the fan at the highest speed requests.
The Diagnostic Trouble Code (DTC) will be set when the commanded state of the driver and the actual state of the control circuit do not match for greater than 5 s.
What are the Possible Causes of the DTC P0691 2018 Chevrolet Silverado?
- Faulty Cooling Fan Control Module
- Cooling Fan Control Module harness is open or shorted
- Cooling Fan Control Module circuit poor electrical connection
- Faulty Engine Control Module (ECM)
How to Fix the DTC P0691 2018 Chevrolet Silverado?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P0691 2018 Chevrolet Silverado code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
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Frequently Asked Questions about P0691 2018 Chevrolet Silverado Code
1. What does OBDII code P0691 mean for a 2018 Chevrolet Silverado?
P0691 indicates low voltage in the cooling fan speed output circuit, which can affect the operation of the cooling fan.
2. What are the common symptoms of code P0691 in a 2018 Chevrolet Silverado?
Symptoms may include engine overheating, reduced cooling fan operation, or the check engine light turning on.
3. What causes code P0691 in a 2018 Chevrolet Silverado?
Common causes include a faulty cooling fan relay, damaged wiring or connectors, or a malfunctioning cooling fan motor.
4. Can driving with code P0691 damage my 2018 Chevrolet Silverado?
Yes, continuing to drive with this code can lead to engine overheating, which can cause severe engine damage.
5. How can I diagnose code P0691 in a 2018 Chevrolet Silverado?
Start by inspecting the cooling fan relay, wiring, and connectors for damage or corrosion, and test the fan motor for proper operation.
6. How do I fix code P0691 on a 2018 Chevrolet Silverado?
Repairs may involve replacing the cooling fan relay, repairing damaged wiring or connectors, or replacing the cooling fan motor.
7. How much does it cost to fix code P0691 on a 2018 Chevrolet Silverado?
The cost varies depending on the issue, but replacing a cooling fan relay typically costs $50-$150, while a cooling fan motor replacement can range from $300-$700.
8. Can a weak battery cause code P0691 on a 2018 Chevrolet Silverado?
Yes, a weak or failing battery can lead to insufficient voltage and trigger this code.
9. Will clearing the code P0691 fix the problem on a 2018 Chevrolet Silverado?
Clearing the code may temporarily turn off the check engine light, but the underlying issue must be repaired to prevent the code from returning.
10. What tools are needed to diagnose code P0691 on a 2018 Chevrolet Silverado?
You’ll need a multimeter to test voltage and continuity, and an OBDII scanner to confirm the code and monitor live data.
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