P0691 2016 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 2016 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 2016 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 2016 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 2016 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 2016 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 2016 GMC Sierra Code
1. What does the OBDII code P0691 mean on a 2016 GMC Sierra?
P0691 indicates a low voltage issue in the cooling fan speed output circuit, which can affect the cooling fan's operation.
2. What are the symptoms of a P0691 code on a 2016 GMC Sierra?
Symptoms may include an illuminated check engine light, engine overheating, an inoperative cooling fan, or unusual fan operation.
3. What causes the P0691 code on a 2016 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 failing powertrain control module (PCM).
4. Can I drive my 2016 GMC Sierra with a P0691 code?
Driving with this code is not recommended as it may lead to engine overheating, which can cause severe engine damage.
5. How do I diagnose the P0691 code on my 2016 GMC Sierra?
Start by inspecting the cooling fan relay, wiring, and connectors for damage or corrosion. Test the cooling fan motor and verify the circuit voltage with a multimeter.
6. How can I fix the P0691 code on a 2016 GMC Sierra?
Repairs may involve replacing a faulty cooling fan relay, repairing damaged wiring, replacing the cooling fan motor, or reprogramming the PCM if necessary.
7. What tools are needed to troubleshoot the P0691 code?
You’ll need an OBDII scanner, multimeter, and possibly wiring diagrams to diagnose and repair the issue.
8. How much does it cost to fix a P0691 code on a 2016 GMC Sierra?
Repair costs vary, but replacing a cooling fan relay may cost $50-$150, while a fan motor replacement could cost $300-$600, depending on labor rates.
9. Can a dirty or corroded connector cause the P0691 code?
Yes, corroded or dirty connectors can disrupt the cooling fan circuit and trigger the P0691 code.
10. Does a P0691 code always mean the cooling fan motor is bad?
No, the issue could also stem from the relay, wiring, or PCM rather than the cooling fan motor itself. Proper diagnosis is essential.
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