P279E – Signal Circuit Range/Performance of the Four-Wheel Drive System

P279E Possible Causes

Faulty all-wheel drive transfer chain
All-wheel drive range circuit wiring harness open or shorted
Poor electrical connection in the all-wheel drive range circuit

How to Fix Code P279E

Check the “Possible Causes” listed above. Visually inspect the wiring harness and related connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

Possible Symptoms

Check engine light illuminated (or service engine soon warning light)

P279E Meaning

The Transmission Control Module (TCM) monitors the signal from the all-wheel drive range signal circuit. The TCM sets the OBDII code when the all-wheel drive transfer range signal circuit signal is outside factory specifications.

P279F – Low All-Wheel Drive Range Signal Circuit

P279F Possible Causes

Faulty all-wheel drive transfer chain
Four-wheel drive range harness is open or shorted
Poor electrical connection in the four-wheel drive range circuit

How to Fix Code P279F

Possible Symptoms

Check Engine Light illuminated (or Service Engine Soon warning light)

P279F Meaning

The Transmission Control Module (TCM) monitors the signal from the four-wheel drive range signal circuit. The TCM sets the OBDII code when the four-wheel drive transfer range signal circuit signal is outside factory specifications.

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The company has developed two prototype vehicles to showcase the potential of their conversion kits: a second-generation Ram and a Toyota Land Cruiser 79-Series. These models serve as technological demonstrators, highlighting how diesel engines can be paired with electric motors to enhance fuel efficiency and reduce emissions. The converted pickups maintain their rugged capabilities while gaining the benefits of electric power, such as instant torque and quieter operation.

Broad Compatibility Across Decades

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Environmental and Economic Benefits

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As the automotive world shifts toward electrification, Edison Motors’ conversion kits offer a pragmatic transition path for diesel-dependent sectors like agriculture, construction, and remote transport. This innovation could accelerate the adoption of electric vehicle technology in regions where infrastructure for fully electric vehicles is still developing, ensuring that sustainability progresses without leaving traditional industries behind.

P27A0 – High Traction Range Signal Circuit

P27A0 Possible Causes

Faulty all-wheel drive powertrain
Four-wheel drive range harness is open or shorted
Poor electrical connection in the four-wheel drive range circuit

How to Fix Code P27A0

Possible Symptoms

Check engine light illuminated (or service engine soon warning light)

P27A0 Meaning

The Transmission Control Module (TCM) monitors the signal from the four-wheel drive range signal circuit. The TCM sets the OBDII code when the four-wheel drive transmission range signal circuit signal is outside factory specifications.

P2600 – Open Coolant Pump Control Circuit

Symptoms and Severity

The severity is generally serious due to its impact on the cooling system. Since it is typically an electrical failure, the PCM cannot fully compensate for it. Partial compensation usually means the cooling fans run all the time (100% duty cycle).

Symptoms of a P2600 code may include:

Malfunction indicator light illuminated
Overheating
The air conditioning system not working properly

Causes

Potential causes for setting this code are as follows:

Open in the coolant pump circuit – likely
Faulty coolant pump – electrically failed open circuit – likely
Failed PCM – unlikely

Diagnostic and Repair Procedures

A good starting point is always to check the Technical Service Bulletins (TSBs) for your specific vehicle. Your issue may be a known problem with a known fix published by the manufacturer and can save you time and money during diagnosis.

Next, locate the B coolant pump (CP-A) on your specific vehicle. This pump is typically found mounted at the front of the engine, on top of the engine, inside the wheel wells, or against the firewall. Once located, visually inspect the connector and wiring. Look for scratches, rubbing, bare wires, burns, or melted plastic. Disconnect the connector and carefully inspect the terminals (the metal parts) inside the connector. See if they appear burnt or have a greenish tint indicating corrosion. Use electrical contact cleaner and a plastic-bristled brush if cleaning the terminals is necessary. Let it dry and apply electrical grease where the terminals make contact.

If you have a scan tool, clear the diagnostic codes from memory and see if the P2600 code returns. If it does not, the connections were likely your problem.

For this particular code, this is the most common area of concern, as are the relays/connections to the relays, with a pump failure being the second most common.

If the code returns, we will need to test the pump and related circuits. Typically, there are 2 wires at each coolant pump. First, disconnect the harness going to the coolant pump. With a digital volt-ohm meter (DVOM), connect one meter lead to one terminal of the pump. Connect the remaining meter lead to the other pump terminal. It should not be open or shorted. Check the resistance specifications for your specific vehicle. If the pump motor is open or shorted (infinite resistance or no resistance/0 ohms), replace the coolant pump.

If this test passes, with a DVOM, check that you have 12V at the coolant pump power circuit (red lead to the pump power circuit, black lead to a good ground). With a scan tool that can activate the coolant pump, turn on the coolant pump. If there is no 12 volts at the pump, repair the wiring from the PCM or relay to the pump, or possibly a faulty PCM.

If that checks out, verify the coolant pump ground circuit. Connect a test light to the positive 12V battery terminal (red terminal) and touch the other end of the test light to the ground circuit going to the coolant pump circuit ground. Using the scan tool to actuate the coolant pump, check if the test light illuminates each time the scan tool actuates the pump. If the test light does not illuminate, it would indicate a circuit problem. If it does light up, wiggle the wire harness going to the pump to see if the test light flickers, indicating an intermittent connection.

If all previous tests have passed and you continue to get a P2600, it would most likely indicate a failing coolant pump, although a faulty PCM cannot be ruled out until the coolant pump has been replaced. If in doubt, seek assistance from a qualified automotive diagnostician. PCMs need to be programmed or calibrated to the vehicle to be installed properly.

Other similar coolant pump codes include P261A, P261B, P261C, and P261D.

P2601 Coolant Pump Control Circuit Performance

Symptoms and Severity

Severity is generally high due to its impact on the cooling system. Since it can be an electrical or mechanical failure, the PCM cannot fully compensate for it. Partial compensation usually means the cooling fans run continuously (100% duty cycle).

Symptoms of a P2601 code may include:

Malfunction indicator light illuminated
Overheating
Air conditioning system not functioning properly

Causes

Potential causes for this code being set are:

Open circuit in the coolant pump – likely
Coolant pump failure – inoperative (mechanically or electrically) – probable
PCM failure – unlikely

Diagnostic and Repair Procedures

A good starting point is always to check the technical service bulletins (TSBs) for your specific vehicle. Your issue might be a known problem with a published manufacturer fix, which can save time and money during diagnosis.

Next, locate the B coolant pump (CP-A) on your specific vehicle. This pump is typically mounted at the front of the engine, on top of the engine, inside the wheel wells, or against the firewall. Once located, visually inspect the connector and wiring. Look for scratches, rubbing, exposed wires, burns, or melted plastic. Disconnect the connector and carefully inspect the terminals (the metal parts) inside. Check if they appear burnt or have a greenish tint indicating corrosion. Use electrical contact cleaner and a plastic-bristled brush if terminal cleaning is needed. Allow to dry and apply electrical grease where the terminals make contact.

If you have a scan tool, clear the diagnostic codes from memory and see if the P2601 code returns. If not, connections were likely your issue.

For this particular code, this is the most common area of concern, along with relay/relay connections, with pump failure being the second most common.

If the code returns, we’ll need to test the pump and related circuits. Typically, there are 2 wires for each coolant pump. First, disconnect the harness going to the coolant pump. With a digital volt ohm meter (DVOM), connect one meter lead to one pump terminal. Connect the remaining meter lead to the other pump terminal. It should not be open or shorted. Check the resistance specifications for your specific vehicle. If the pump motor is open or shorted (infinite resistance or no resistance/0 ohms), replace the coolant pump.

If this test passes, use a DVOM to verify you have 12V at the coolant pump power circuit (red lead to pump power circuit, black lead to a good ground). With a scan tool capable of activating the coolant pump, turn on the coolant pump. If there’s no 12 volts at the pump, repair the wiring from the PCM or relay to the pump, or possibly a faulty PCM.

If that checks out, verify the coolant pump is properly grounded. Connect a test light to the positive 12V battery terminal (red terminal) and touch the other end of the test light to the ground circuit going to the coolant pump circuit ground. Using the scan tool to activate the coolant pump, check if the test light illuminates each time the scan tool activates the pump. If the test light does not illuminate, it would indicate a circuit problem. If it lights up, wiggle the wiring harness going to the pump to see if the test light flickers, indicating an intermittent connection.

If all previous tests pass and you continue to get a P2601, it would most likely indicate a failing coolant pump, although a faulty PCM cannot be ruled out until the coolant pump has been replaced. When in doubt, seek assistance from a qualified automotive diagnostician. PCMs need to be programmed or calibrated to the vehicle to be installed correctly.

Other similar coolant pump codes include P261A, P261B, P261C, and P261D.

P2602 Coolant Pump A Control Circuit Low

Symptoms

and Severity

The severity is generally high due to its impact on the cooling system. Since it is typically an electrical failure, the PCM cannot fully compensate for it. Partial compensation usually means the cooling fans run continuously (100% duty cycle).

Symptoms of a P2602 code may include:

Malfunction indicator light illuminated
Overheating
Air conditioning system not functioning properly

Causes

Potential causes for this code are as follows:

Open circuit in the coolant pump – likely
Failed coolant pump – likely
Failed PCM – unlikely

Diagnostic and Repair Procedures

A good starting point is always to check the Technical Service Bulletins (TSBs) for your specific vehicle. Your issue might be a known problem with a published fix from the manufacturer, which can save time and money during diagnosis.

Next, locate the B coolant pump (CP-A) on your specific vehicle. This pump is typically mounted at the front of the engine, on top of the engine, inside the wheel wells, or against the firewall. Once located, visually inspect the connector and wiring. Look for scratches, rubbing, exposed wires, burns, or melted plastic. Disconnect the connector and carefully inspect the terminals (the metal parts) inside. Check if they appear burnt or have a greenish tint indicating corrosion. Use electrical contact cleaner and a plastic-bristled brush if terminal cleaning is necessary. Allow it to dry and apply electrical grease where the terminals make contact.

If you have a scan tool, clear the diagnostic codes from memory and see if the P2602 code returns. If it does not, the connections were likely the issue.

For this particular code, the most common area of concern is the relays and relay connections, with pump failure being the second most common.

If the code returns, we will need to test the pump and related circuits. Typically, there are 2 wires for each coolant pump. First, disconnect the harness going to the coolant pump. With a digital volt-ohm meter (DVOM), connect one meter lead to one terminal of the pump. Connect the remaining meter lead to the other pump terminal. It should not be open or shorted. Check the resistance specifications for your specific vehicle. If the pump motor is open or shorted (infinite resistance or no resistance/0 ohms), replace the coolant pump.

If this test passes, use a DVOM to check for 12V at the coolant pump power circuit (red lead to the pump power circuit, black lead to a good ground). With a scan tool capable of activating the coolant pump, turn on the coolant pump. If there is no 12 volts at the pump, repair the wiring from the PCM or relay to the pump, or possibly a faulty PCM.

If that is okay, check the coolant pump ground circuit. Connect a test light to the positive 12V battery terminal (red terminal) and touch the other end of the test light to the ground circuit going to the coolant pump circuit ground. Using the scan tool to activate the coolant pump, check if the test light illuminates each time the scan tool activates the pump. If the test light does not illuminate, it would indicate a circuit problem. If it does light up, wiggle the wiring harness going to the pump to see if the test light flickers, indicating an intermittent connection.

If all previous tests pass and you continue to get a P2602, it would most likely indicate a faulty coolant pump, although a faulty PCM cannot be ruled out until the coolant pump has been replaced. If in doubt, seek assistance from a qualified automotive diagnostician. PCMs need to be programmed or calibrated to the vehicle to be installed correctly.

Other similar coolant pump codes include P261A, P261B, P261C, and P261D.

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Redefining the Pickup for City Living

The automotive landscape is evolving, and the 2025 Hyundai Santa Cruz stands at the forefront of this transformation. Designed for those who need utility without the bulk of a traditional truck, this vehicle masterfully blends the comfort of an SUV with the functionality of a pickup. Its sleek, car-like profile and manageable size make it ideal for navigating tight urban streets and parking with ease, offering a driving experience that larger trucks simply cannot match.

Versatility Meets Modern Design

Under the hood, the Santa Cruz is expected to feature efficient yet capable engine options, providing ample power for daily commutes and weekend getaways. The innovative integrated bed is not just for show; it’s a practical space with features like a lockable tonneau cover and an available power outlet, perfect for securing gear or powering tools for a spontaneous project. The interior continues this theme of smart design, with a spacious, tech-forward cabin that prioritizes passenger comfort and connectivity, making every journey enjoyable.

Why It Appeals to Non-Truck Buyers

Many drivers are hesitant to commit to a conventional pickup due to its often cumbersome nature and rugged ride quality. The Santa Cruz directly addresses these concerns by delivering a smooth, refined ride akin to a premium crossover, coupled with a versatile bed that handles everything from grocery runs to outdoor adventure gear. It’s the ideal solution for active individuals and small families who require occasional hauling capacity without sacrificing daily drivability or fuel efficiency.

In a market saturated with similar options, the 2025 Hyundai Santa Cruz carves out a unique niche. It proves that you don’t need a massive vehicle to be prepared for anything, offering a compelling alternative that combines style, practicality, and innovation in one attractive package.

P2603 High Coolant Pump Control Circuit A

Symptoms and Severity

Symptoms of a P2603 code may include:

Malfunction indicator light on
Overheating
The air conditioning system not working properly

Causes

Potential causes for this code being set are as follows:

Open in the coolant pump circuit – likely
Coolant pump failure – likely
PCM failure – unlikely

Diagnostic and Repair Procedures

A good starting point is always to check the Technical Service Bulletins (TSBs) for your specific vehicle. Your issue may be a known problem with a known fix released by the manufacturer and can save you time and money during diagnosis.

Next, locate the B coolant pump (CP-A) on your specific vehicle. This pump is typically found mounted at the front of the engine, on top of the engine, inside the wheel wells, or against the firewall. Once located, visually inspect the connector and wiring. Look for scratches, rubbing, bare wires, burns, or melted plastic. Disconnect the connector and carefully inspect the terminals (the metal parts) inside the connector. See if they appear burnt or have a greenish tint indicating corrosion. Use electrical contact cleaner and a plastic bristle brush if cleaning the terminals is necessary. Let it dry and apply electrical grease where the terminals make contact.

If you have a scan tool, clear the diagnostic codes from memory and see if the P2603 code returns. If it does not, the connections were likely your problem.

For this particular code, this is the most common area of concern, as are the relays/connections to the relays, with pump failure being the second most common.

If the code returns, we will need to test the pump and related circuits. Typically, there are 2 wires at each coolant pump. First, disconnect the harness going to the coolant pump. With a digital volt ohm meter (DVOM), connect one meter lead to one terminal of the pump. Connect the remaining meter lead to the other pump terminal. It should not be open or shorted. Check the resistance specifications for your specific vehicle. If the pump motor is open or shorted (infinite resistance or no resistance/0 ohms), replace the coolant pump.

If that checks out, verify the coolant pump ground circuit. Connect a test light to the positive 12V battery terminal (red terminal) and touch the other end of the test light to the ground circuit going to the coolant pump circuit ground. Using the scan tool to actuate the coolant pump, check if the test light illuminates each time the scan tool actuates the pump. If the test light does not illuminate, it would indicate a problem with the ground circuit. If it does light up, wiggle the wiring harness going to the pump to see if the test light flickers, indicating an intermittent connection.

If all previous tests have passed and you continue to get a P2603, it would most likely indicate a faulty coolant pump, although a faulty PCM cannot be ruled out until the coolant pump has been replaced. If in doubt, seek assistance from a qualified automotive diagnostician. PCMs need to be programmed or calibrated to the vehicle to be installed correctly.

Other similar coolant pump codes include P261A, P261B, P261C, and P261D.

P2604 Intake Air Heater A Circuit Performance

Code Severity and Symptoms

The severity of this code is normally moderate, but can be severe depending on the specific malfunction.

Symptoms of a P2604 diagnostic code may include:

Engine does not start
Longer than normal starting time
Check engine light illuminated
Rough idle in cold weather
Engine stalls

Causes

Generally, potential causes for this code include:

Faulty heating element relay
Defective heating element
Faulty temperature sensor
Corroded or damaged connector
Damaged or restricted air duct
Faulty or damaged wiring
Faulty blower motor
Faulty PCM

What are the most common repairs?

Replacement of the heating element
Replacement of the temperature sensor
Replacement of the heating element relay
Cleaning corrosion from connectors
Repairing or replacing wiring
Replacement of damaged air ducts
Replacement of the blower motor
PCM replacement

Diagnostic and Repair Procedures

The first step in the troubleshooting process for any malfunction is to search for Technical Service Bulletins (TSBs) for the specific vehicle by year, model, and powertrain. In some circumstances, this can save you considerable time in the long run by pointing you in the right direction.

The intake air heater circuit may not operate automatically if the ambient air or engine temperature is above the manufacturer’s set limit. The circuit should activate if it is commanded “ON” with a scan tool, or if power is manually applied.

Basic Steps

Check the heating element, does it turn “ON”
NOTE: Do not touch the heating element or heat shield
Check the blower motor, does it turn “ON”
Visually inspect the circuit connections and wiring for obvious faults
Visually inspect the condition of the air ducts for obvious faults
Check electrical connections for security and corrosion

Advanced Steps

Advanced steps become very vehicle-specific and require appropriate advanced equipment to perform accurately. These procedures require a digital multimeter and the specific vehicle technical references. Voltage requirements will be highly specific to the vehicle’s year, model, and diesel engine.

Specific Checks:

Note: On applications equipped with mass air flow sensors, the intake air temperature sensor is integrated into the sensor body. Consult the technical data to determine the correct pins associated with the sensor.

Specific checks should be performed using the troubleshooting guidelines for the specific vehicle using the technical manual or online reference material. These steps will guide you through the process of checking the power and ground for each component in the intake air heater circuit in the correct order. If voltage is correct for a component that is not functioning, that component is likely faulty and needs replacement. If power is not available to operate the circuit, continuity checks may be necessary to identify faulty wiring or components.

I hope the information in this article has helped point you in the right direction to correct your intake air heater circuit malfunction issue. This article is strictly informational, and the technical data and service bulletins specific to your vehicle should always take priority.