P0691 2015 GMC Sierra 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 2015 GMC Sierra 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 2015 GMC Sierra 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 2015 GMC Sierra?
- 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 2015 GMC Sierra?
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 2015 GMC Sierra 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 2015 GMC Sierra Code
1. What does the OBDII code P0691 mean on a 2015 GMC Sierra?
The P0691 code indicates a low voltage issue 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 2015 GMC Sierra?
Symptoms may include engine overheating, the cooling fan not turning on, an illuminated check engine light, or reduced A/C performance.
3. What causes the P0691 code to appear on a 2015 GMC Sierra?
Common causes include a faulty cooling fan relay, damaged wiring or connectors in the fan circuit, a malfunctioning cooling fan motor, or a failed powertrain control module (PCM).
4. Can I drive my 2015 GMC Sierra with a P0691 code?
It is not recommended to drive the vehicle with this code active, as it may lead to engine overheating and potential damage if the cooling fan is not functioning properly.
5. How do I diagnose the P0691 code on a 2015 GMC Sierra?
To diagnose, check the cooling fan relay, inspect wiring and connectors for damage or corrosion, and test the cooling fan motor for proper operation.
6. How do I fix the P0691 code on a 2015 GMC Sierra?
Repairs may include replacing a faulty cooling fan relay, repairing or replacing damaged wiring, or replacing the cooling fan motor if it has failed.
7. Can a blown fuse cause the P0691 code on a 2015 GMC Sierra?
Yes, a blown cooling fan fuse can interrupt the circuit and trigger the P0691 code.
8. How much does it cost to repair the P0691 code on a 2015 GMC Sierra?
Repair costs can vary but typically range from $50 to $300 depending on whether the issue is with the relay, wiring, or cooling fan motor.
9. Will clearing the P0691 code fix the problem on a 2015 GMC Sierra?
Clearing the code will turn off the check engine light temporarily, but the underlying issue must be resolved to prevent the code from returning.
10. Can a bad PCM cause the P0691 code on a 2015 GMC Sierra?
While rare, a malfunctioning PCM can cause the P0691 code if it fails to properly control the cooling fan circuit.
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