P0696 Cooling Fan 3 Relay Control Circuit High

The P0696 – Cooling Fan 3 Relay Control Circuit High diagnostic trouble code (DTC) indicates that the engine control module has detected higher-than-expected voltage in the control circuit for Cooling Fan 3.

The cooling fan system is responsible for controlling engine temperature and, on many vehicles, helping maintain proper temperatures for the air-conditioning system. Modern vehicles can use multiple electric cooling fans or several fan-speed stages. The exact meaning of “Fan 3” depends on the vehicle's electrical design.

P0696 is an electrical circuit code. It does not automatically mean that the cooling fan motor itself has failed.

What Does P0696 Mean?

In simple terms:

The ECU sees too much voltage in the Cooling Fan 3 relay control circuit.

A simplified system can look like:

ECU → Fan Relay Control → Cooling Fan Relay → Cooling Fan → Ground

The ECU monitors the electrical behavior of the relay control circuit.

If the voltage is higher than the expected value, the ECU can store P0696.

The exact voltage threshold varies by manufacturer.

What Is Cooling Fan 3?

“Cooling Fan 3” does not necessarily mean that the vehicle physically has a third separate fan.

Depending on the vehicle, it can refer to:

• A third cooling fan

• A third fan relay

• A high-speed fan stage

• A specific relay within a multi-relay fan system

• A particular control circuit

For example, a vehicle might use:

Fan 1 → Low speed

Fan 2 → Medium speed

Fan 3 → High speed

Another vehicle may use three separate fans.

Therefore, the vehicle-specific wiring diagram is important.

What Causes P0696?

Possible causes include:

• Faulty cooling fan relay

• Stuck relay contacts

• Short to battery voltage

• Damaged relay control wiring

• Incorrectly installed wiring

• Corroded connector

• Faulty cooling fan control module

• ECU driver circuit problem

• Incorrect relay

• Aftermarket electrical modification

• Wiring harness damage

The cooling fan motor itself can also be involved indirectly, but P0696 specifically concerns the relay control circuit being too high.

Can a Bad Cooling Fan Relay Cause P0696?

Yes.

A relay with internally stuck or damaged contacts can produce abnormal voltage in the control circuit.

Possible relay problems include:

• Contacts welded together

• Internal coil failure

• Incorrect relay installation

• Internal short

• Corrosion

• Mechanical sticking

The relay should be tested rather than replaced automatically.

Can a Short to Battery Cause P0696?

Yes.

A control wire that should normally be switched or controlled by the ECU may be contacting battery voltage.

For example:

Battery voltage → Damaged control wire → Fan relay control circuit

This can cause the ECU to detect a voltage level that is higher than expected.

Inspect the harness carefully for:

• Chafing

• Melted insulation

• Pinched wires

• Incorrect repairs

• Contact with power wires

Can a Bad ECU Cause P0696?

Yes, but it is less common.

The ECU may use an internal transistor or driver to control the fan relay.

If that driver circuit fails, the control circuit may behave abnormally.

However, the ECU should only be considered after:

• Relay testing

• Wiring inspection

• Voltage testing

• Connector inspection

• Power and ground checks

have been completed.

Can a Cooling Fan Control Module Cause P0696?

Yes, depending on the vehicle.

Some vehicles use a dedicated cooling fan control module rather than having the ECU control the relay directly.

A failure in this module can cause abnormal relay-control voltage.

Symptoms of P0696

Possible symptoms include:

Check Engine Light

The MIL may illuminate when the ECU detects the fault.

Cooling fan not operating correctly

The affected fan or fan stage may not operate when required.

Fan running continuously

A control fault can sometimes cause the fan to remain active.

Engine overheating

If the required fan stage does not operate, coolant temperature can rise.

Air-conditioning problems

Cooling fans are often required for proper A/C condenser cooling.

A/C performance decreases

The air conditioner may become less effective, especially at low vehicle speeds.

Fan operating at the wrong speed

The cooling system may remain on low speed or fail to switch to a higher speed.

Can P0696 Cause Overheating?

Yes.

This is one of the main reasons the code should not be ignored.

If Cooling Fan 3 is required for high-temperature operation and it cannot be controlled correctly, engine coolant temperature can rise.

Overheating can cause serious engine damage.

If the temperature gauge rises above normal, stop the vehicle and investigate the cooling system.

Can P0696 Cause the Fan to Run Continuously?

It can.

The exact behavior depends on how the fan control system is designed.

Some vehicles enter a fail-safe strategy when a fan-control fault is detected.

This can result in:

• Continuous fan operation

• High-speed fan operation

• Fan operation after the engine is switched off

However, not every vehicle will behave this way.

Can P0696 Affect the Air Conditioner?

Yes.

The engine cooling fans also help remove heat from the A/C condenser.

If fan control is abnormal, the vehicle may experience:

• Poor A/C cooling at idle

• Reduced cooling at low speed

• A/C compressor cycling

• A/C system shutdown

The exact symptoms depend on the vehicle.

Can P0696 Cause a Dead Battery?

Potentially.

If a cooling fan remains running after the engine is switched off, it can discharge the battery.

For example:

Fan relay stuck → Cooling fan remains active → Battery continues to discharge

If you find that the cooling fan runs continuously after shutting off the engine, the relay and control circuit should be inspected promptly.

Can a Blown Fuse Cause P0696?

A blown fuse usually causes a loss of power rather than a high control-circuit voltage, so it is not the most direct explanation for P0696.

However, a fuse or relay problem can alter the behavior of the fan-control circuit.

Check the relevant fuses and power supply as part of the diagnosis.

Can a Bad Cooling Fan Motor Cause P0696?

It can be related, but it is not the first component to suspect from the code alone.

A failed motor can cause excessive current, no current, or abnormal fan operation.

However, P0696 specifically points toward a high relay control circuit condition.

The relay control circuit should therefore be tested before replacing the motor.

How Is P0696 Diagnosed?

A systematic electrical diagnosis is important.

1. Scan all control modules

Check for:

• Stored DTCs

• Pending DTCs

• Cooling-system codes

• Temperature-sensor codes

• Communication codes

Other codes may explain why the fan system is behaving incorrectly.

2. Identify Cooling Fan 3

Use the vehicle wiring diagram to determine exactly what “Fan 3” represents.

3. Inspect the fuse and relay box

Look for:

• Corrosion

• Water intrusion

• Melted plastic

• Damaged terminals

• Incorrect relay installation

4. Test the relay

Verify the relay coil and switching contacts according to manufacturer specifications.

5. Check the control voltage

Measure the voltage at the relay control circuit.

Compare the reading with the manufacturer's specification.

6. Check for a short to battery voltage

Inspect the control wire for unwanted battery voltage.

7. Inspect the wiring harness

Look for:

• Chafing

• Pinched wires

• Melted insulation

• Broken wires

• Previous repairs

8. Test the fan motor

Verify that the fan operates correctly when commanded.

9. Check the cooling fan control module

If the vehicle uses one, verify its power, ground, input, and output circuits.

10. Check the ECU

Only after the external circuit has been verified should an ECU driver failure be considered.

Can a Multimeter Diagnose P0696?

Yes.

A multimeter is useful for checking:

• Relay coil resistance

• Control-circuit voltage

• Battery voltage

• Voltage drop

• Continuity

• Shorts to power

• Shorts to ground

However, the measurement must be interpreted according to the vehicle's wiring design.

Can a Scan Tool Help?

Yes.

A capable scan tool can provide useful information such as:

• Engine coolant temperature

• Fan command

• Fan duty cycle

• Fan status

• Relay activation

• Related DTCs

Some vehicles also allow an active test, where the technician commands the cooling fan on and off.

This can make diagnosis considerably easier.

What If P0696 Appears With a Coolant Temperature Sensor Code?

This combination is important.

The ECU may activate cooling fans based on coolant temperature.

If the temperature sensor is reporting an incorrect value, fan operation can become abnormal.

Therefore, if P0696 appears with a coolant-temperature-related DTC, diagnose both systems together.

What If the Fan Runs All the Time?

Check:

• Fan relay

• Relay control wire

• Cooling fan control module

• ECU command

• Coolant temperature sensor

• Short to battery

• Shorted relay contacts

A stuck relay is a common possibility, but it should be confirmed.

What If the Fan Does Not Run?

Check:

• Fan fuse

• Fan relay

• Fan motor

• Relay power supply

• Relay control circuit

• Fan ground

• Fan control module

• ECU command

Do not assume that P0696 automatically means the fan motor is defective.

What If P0696 Appears After Engine Repair?

Inspect the wiring around the engine bay.

Cooling-fan wiring is exposed to:

• High temperatures

• Vibration

• Water

• Road debris

A harness may have been pinched, incorrectly routed, or left disconnected during repair.

What If P0696 Appears After Electrical Work?

Check for:

• Incorrect relay

• Wrong fuse

• Incorrect wiring

• Added accessories

• Modified fan-control wiring

• Poor electrical repairs

An incorrect relay can significantly change the electrical behavior of the control circuit.

Is P0696 a Serious Problem?

It can be.

The primary concern is engine overheating.

If the affected fan or fan stage is required to maintain engine temperature, continued driving can cause:

• Excessive coolant temperature

• Head-gasket damage

• Cylinder-head damage

• Engine damage

If the temperature gauge rises above normal, do not continue driving.

Can You Drive With P0696?

If the engine temperature remains completely normal and the cooling fan operates correctly, a short trip for diagnosis may be possible.

However, monitor the temperature carefully.

Do not continue driving if:

• The engine overheats

• The temperature warning appears

• Steam comes from the engine compartment

• Coolant temperature rises rapidly

• The fan does not operate when required

How Is P0696 Repaired?

The repair depends on the confirmed cause.

Possible repairs include:

• Replacing a faulty fan relay

• Repairing a shorted control wire

• Repairing damaged wiring

• Repairing a connector

• Replacing a damaged terminal

• Repairing the fan control module

• Replacing a defective cooling fan motor

• Correcting incorrect electrical modifications

• Repairing an ECU driver circuit

• Replacing the ECU when internal failure is confirmed

Does P0696 Require Cooling Fan Replacement?

No.

The code identifies a high relay control circuit condition, not necessarily a defective fan motor.

Test the electrical circuit first.

Does P0696 Require Relay Replacement?

Not automatically.

The relay is one of the components that should be tested.

A shorted control wire or ECU driver problem can produce similar symptoms.

Does P0696 Require ECU Replacement?

Usually not.

The ECU should be considered only after the relay, wiring, connectors, fan-control module, power supply, and grounds have been verified.

Common Diagnostic Mistakes

Replacing the cooling fan immediately

The fault may be in the relay control circuit.

Replacing the relay without testing the wiring

A short to battery voltage can cause the replacement relay to behave incorrectly.

Ignoring the cooling fan control module

Some vehicles do not use a simple relay-only system.

Ignoring overheating risk

Even an electrical code can lead to serious mechanical engine damage if the cooling system cannot operate correctly.

Ignoring other DTCs

Coolant-temperature and communication codes can provide important clues.

Replacing the ECU too early

External electrical faults should be eliminated first.

P0695 vs. P0696 vs. P0697

These codes are related but identify different electrical conditions.

P0695 – Cooling Fan 3 Relay Control Circuit Malfunction

General fault in the Cooling Fan 3 relay control circuit.

P0696 – Cooling Fan 3 Relay Control Circuit High

The control circuit voltage is higher than expected.

P0697 – Sensor Reference Voltage "C" Circuit/Open

This is a different circuit entirely and concerns sensor reference voltage rather than cooling-fan relay control.

The important distinction is:

P0695 → General Fan 3 relay control problem

P0696 → Fan 3 relay control circuit voltage too high

P0697 → Sensor Reference "C" circuit open

How Do You Clear P0696?

The correct procedure is:

Scan all modules → Record all DTCs → Identify Cooling Fan 3 → Inspect fuse and relay → Test relay → Measure control voltage → Check for short to battery → Inspect wiring → Test fan motor → Test fan control module → Verify ECU command → Repair the confirmed fault → Clear codes → Perform an active fan test → Road test → Rescan

If P0696 returns, the high-voltage condition in the Fan 3 relay control circuit has not been resolved.

Final Thoughts on P0696

P0696 – Cooling Fan 3 Relay Control Circuit High indicates that the ECU has detected higher-than-expected voltage in the control circuit responsible for Cooling Fan 3.

The actual cause can be a faulty relay, short to battery voltage, damaged wiring, connector problem, cooling fan control module fault, incorrect electrical modification, or, less commonly, an ECU driver failure.

The term “Fan 3” is vehicle-specific. It may refer to a third physical fan, a third relay, or a particular fan-speed stage.

The best diagnostic approach is:

Identify Fan 3 → Check the relay → Measure control voltage → Check for short to battery → Inspect wiring and connectors → Test the fan → Check the fan control module → Verify ECU operation.

Most importantly, do not assume that P0696 means the cooling fan motor needs to be replaced. It is specifically a high control-circuit voltage code, so the relay and its electrical control circuit should be investigated first.