AutoCodes – Chevrolet – P0691 Chevrolet

P0691 Chevrolet Code - Cooling Fan 1 Control Circuit Low

Quick Answer

The engine cooling fan system is composed of electric cooling fan and a cooling fan control module. Common causes include Faulty Cooling Fan 1 Relay, Cooling Fan 1 Relay harness is open or shorted, Cooling Fan 1 Relay 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 Chevrolet indicates Cooling Fan 1 Control Circuit Low.
Common causes: Common causes include Faulty Cooling Fan 1 Relay, Cooling Fan 1 Relay harness is open or shorted, Cooling Fan 1 Relay 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.

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Code Popularity 5,041

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jul 19, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0691 Chevrolet Description

The engine cooling fan system is composed of electric cooling fan and a cooling fan control module. The Engine Control Module (ECM) controls the fan speed by sending a Pulse Width Modulated (PWM) signal to the cooling fan control module. The cooling fan control module varies the voltage drop across the cooling fan motor in relation to the pulse width modulated signal, allowing the cooling fan to operate at variable speeds. The cooling fan speed is affected by many different operating conditions and the ECM will adjust the duty cycle based on cooling system requirements.
Generally, the ECM will operate the cooling fan at specific percentages but, may scale the percentages either higher or lower in response to generator demand. The percentages at which the cooling fan operates may vary between vehicle lines and engines.
The cooling fan control module is thermally protected to prevent module damage in the case of a short circuit condition in the cooling fan motor. The scan tool output control is only capable of operating the cooling fan in the speed percentages allowed by the ECM. When multiple cooling fan speed requests are received, the ECM operates the fan at the highest of the 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.

**Cooling Fan design may vary

OBDII Code P0691 Chevrolet - Cooling Fan 1 Control Circuit Low - AutoCodes.com — P0691 Chevrolet Code - Cooling Fan 1 Control Circuit Low

What does this mean?

What are the Possible Causes of the DTC P0691 Chevrolet?

Faulty Cooling Fan 1 Relay
Cooling Fan 1 Relay harness is open or shorted
Cooling Fan 1 Relay circuit poor electrical connection
Faulty Cooling Fan 1
Faulty Cooling Fan Control Module
Faulty Engine Control Module (ECM)

How to Fix the DTC P0691 Chevrolet?

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 Chevrolet 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.

Need more information about the P0691 Chevrolet code?

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Need Help with the Code?

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Information for Specific Chevrolet Models

P0691 2014 Chevrolet Silverado — Cooling Fan Speed Output Circuit Low Voltage
P0691 2015 Chevrolet Silverado — Cooling Fan Speed Output Circuit Low Voltage
P0691 2016 Chevrolet Silverado — Cooling Fan Speed Output Circuit Low Voltage
P0691 2017 Chevrolet Silverado — Cooling Fan Speed Output Circuit Low Voltage
P0691 2018 Chevrolet Silverado — Cooling Fan Speed Output Circuit Low Voltage

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0691 Chevrolet Code

1. What are the common symptoms of OBDII code P0691 in a Chevrolet related to the Cooling Fan 1 Control Circuit Low?

- Common symptoms may include overheating of the engine, illuminated Check Engine Light, and decreased cooling fan operation.

2. What are the possible causes of OBDII code P0691 in a Chevrolet indicating Cooling Fan 1 Control Circuit Low?

- Potential causes may include a faulty cooling fan relay, damaged wiring or connections in the cooling fan circuit, or a malfunctioning engine control module (ECM).

3. How can I diagnose OBDII code P0691 in my Chevrolet for Cooling Fan 1 Control Circuit Low?

- Diagnose the code by checking the cooling fan relay, inspecting the wiring and connectors for any damage, and testing the ECM for proper functionality using a scan tool.

4. Can a malfunctioning coolant temperature sensor trigger OBDII code P0691 indicating Cooling Fan 1 Control Circuit Low in a Chevrolet?

- Yes, a faulty coolant temperature sensor can cause the cooling fan to operate improperly, leading to the triggering of code P0691.

5. What are some tips for repairing OBDII code P0691 related to Cooling Fan 1 Control Circuit Low in a Chevrolet?

- Repair tips may include replacing the cooling fan relay, repairing any damaged wiring or connectors, and reprogramming or replacing the ECM if necessary.

6. Is it safe to continue driving my Chevrolet with OBDII code P0691 indicating Cooling Fan 1 Control Circuit Low?

- It is not recommended to drive the vehicle with this code active as it can lead to engine overheating and potential damage.

7. How urgent is it to address OBDII code P0691 in a Chevrolet related to Cooling Fan 1 Control Circuit Low?

- It is important to address this code promptly to prevent engine overheating and potential costly repairs.

8. Can resetting the ECM clear OBDII code P0691 for Cooling Fan 1 Control Circuit Low in a Chevrolet?

- Resetting the ECM may temporarily clear the code, but it is essential to diagnose and repair the underlying issue to prevent the code from reoccurring.

9. Are there any preventive measures to avoid OBDII code P0691 in a Chevrolet related to Cooling Fan 1 Control Circuit Low?

- Regularly inspecting the cooling fan system, maintaining proper coolant levels, and addressing any cooling system issues promptly can help prevent this code.

10. Will driving at lower speeds or in cooler weather affect OBDII code P0691 in a Chevrolet indicating Cooling Fan 1 Control Circuit Low?

- Driving conditions can impact the cooling fan's operation, potentially affecting the triggering of the code. It is best to address the underlying issue regardless of driving conditions.