P0691 2014 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 2014 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 2014 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 2014 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 2014 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 2014 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 2014 GMC Sierra Code
1. What does the OBDII code P0691 mean on a 2014 GMC Sierra?
The P0691 code indicates a low voltage issue in the cooling fan speed output circuit, which affects the proper operation of the cooling fan.
2. What are the common symptoms of the P0691 code in a 2014 GMC Sierra?
Common symptoms include engine overheating, an illuminated check engine light, cooling fan not functioning, and possible A/C performance issues.
3. What causes the P0691 code to occur in a 2014 GMC Sierra?
Typical causes include a faulty cooling fan relay, damaged wiring or connectors in the cooling fan circuit, a defective cooling fan motor, or a malfunctioning Powertrain Control Module (PCM).
4. Can I drive my 2014 GMC Sierra with the P0691 code?
Driving with the P0691 code is not recommended, as it can lead to engine overheating and potential damage if the cooling fan is not operating properly.
5. How do I diagnose the P0691 code on my 2014 GMC Sierra?
Diagnosis involves checking the cooling fan relay, inspecting wiring and connectors for damage, testing the cooling fan motor, and using a multimeter to measure circuit voltage.
6. How can I fix the P0691 code on a 2014 GMC Sierra?
Repairs may include replacing a faulty cooling fan relay, repairing damaged wiring, replacing the cooling fan motor, or reprogramming or replacing the PCM if necessary.
7. Is the cooling fan relay a common culprit for the P0691 code?
Yes, a faulty cooling fan relay is a common cause of the P0691 code and should be one of the first components inspected.
8. Will clearing the P0691 code with a scanner fix the issue?
Clearing the code may temporarily turn off the check engine light, but the underlying issue causing the low voltage must be resolved to prevent the code from returning.
9. How much does it cost to repair the P0691 code on a 2014 GMC Sierra?
Repair costs vary depending on the cause, ranging from $50 for a new relay to $500 or more if the cooling fan motor or PCM needs replacement.
10. Can a bad PCM cause the P0691 code in a 2014 GMC Sierra?
While less common, a malfunctioning PCM can cause the P0691 code if it fails to properly control the cooling fan circuit.
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