Fault code P2602 – coolant pump “A” control circuit low

Fault code P2602 is called “Coolant Pump “A” Control Circuit Low” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.

Technical description and explained code P2602

This diagnostic trouble code (DTC) is a generic code. Error P2602 is considered a generic code because it applies to all makes and models of vehicles. Although the specific repair steps may vary slightly depending on the model.

Fault code P2602 – coolant pump

When the PCM (transmission control module) detects a problem in the auxiliary coolant pump control circuit, it records code P2602. The check engine light also illuminates. This code can be detected by a number of supporting control modules, not just the PCM.

At lower speeds, the engine cannot push as much coolant through the system as may be needed to prevent overheating. Thus, to keep the cooling system from overheating. The coolant pump works by electronically circulating through the system. This occurs when the vehicle is idling or running at low rpm.

If code P2602 is stored, in the PCM memory, it indicates the following problem. The coolant pump circuit is operating outside the manufacturer’s settings.

Troubleshooting actions may vary depending on the manufacturer, coolant pump type, and wire colors.

Symptoms of vehicle malfunctions

The main signal that an error P2602 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

  1. Check engine control lamp on the control panel will light up (the code will be written to the ECM memory as a fault).
  2. The engine may be overheating.
  3. The air conditioning system is not working properly.

Driving while overheating can cause irreparable damage to the engine, which may cost significant money to repair. There is a good chance that your car will overheat more and more often. Especially at low speeds, until you solve the P2602 problem.

Factors that can cause this error code

The error code P2602 can mean that one or more of the following problems have occurred:

  • Shorted, broken wiring or connectors in the coolant pump wiring harness.
  • Open or loose ground wire.
  • Defective coolant pump.
  • Failed PCM is unlikely.

How to fix or reset OBD-2 code P2602

Some suggested steps for troubleshooting and fix the error code P2602:

  1. Repair or replace wiring and harness connectors to pump.
  2. Reconnect or repair loose or broken ground wires.
  3. Replacement of the coolant pump.
  4. Replace faulty PCM.

Diagnose and repair of problems

The first thing to do is to check the technical service bulletins (TSB) for your particular vehicle. Your P2602 problem may be a known problem with a known fix issued by the manufacturer. This can save you time and money during diagnosis.

Then locate the coolant pump on your particular vehicle. This actuator is usually mounted at the front of the engine. On top of the engine, inside the wheel arches or against the bulkhead.

Wiring test

Once found, visually inspect the connector and wiring. Look for scratches, scuffs, exposed wires, burn spots, or melted plastic. Disconnect the connector and carefully inspect the terminals inside the connector.

Look to see if they look burnt or have a green tint indicating corrosion. If you need to clean the terminals, use an electrical contact cleaner and a plastic-bristle brush. Allow to dry and apply electrical grease to the contact areas of the terminals.

If you have a diagnostic scanner, clear the diagnostic trouble codes from the memory and see if code P2602 returns. If it doesn’t, the problem is most likely wiring related.

Pump check

If the P2602 code returns, we will need to test the pump and its associated circuits. There are usually 2 wires on each pump. First, disconnect the harness going to the coolant pump.

Using a digital multimeter, connect one lead of the meter to one terminal on the pump. Connect the remaining meter lead to the other terminal on the pump. It should not be open or shorted.

Check the resistance characteristics for your particular vehicle. If the pump is shorted, the resistance will be infinite or nonexistent. If so, replace the coolant pump.

If this test is passed, use a multimeter to make sure you have 12 volts applied to the coolant pump supply circuit. Red wire to drive power circuit, black wire to ground.

With a diagnostic tool that can activate the coolant pump, turn on the drive. If there is no 12 volts on the drive, repair the wiring from the PCM or relay to the pump. Also in this case, the PCM may be faulty.

If all is well, make sure you have a good ground connection at the coolant pump. Connect the test lamp to the plus end of the 12V battery (red lead). And touch the other end of the test lamp to the ground circuit. The coolant pump ground circuit.

Using the diagnostic tool to actuate the coolant pump. Check to see if the indicator light illuminates each time the diagnostic tool powers the pump.

If the indicator light does not come on, it indicates a faulty circuit. If it lights up, jiggle the wiring harness going to the pump. To see if the check lamp blinks, indicating an intermittent connection.

If all of the previous tests are passed and you continue to get error P2602. You most likely have a faulty coolant pump. Although a failed PCM cannot be ruled out until the coolant pump is replaced.

If you’re not sure, get help from a qualified automotive diagnostician. The PCM must be programmed or calibrated for the specific vehicle in order to properly install it.

On which vehicles does this problem occur most frequently

Fault code P2602 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • Audi
  • Citroen
  • Ford
  • Honda (Accord, Vezel)
  • Jeep (Grand Cherokee)
  • Lexus
  • Mercedes-Benz (Sprinter)
  • Nissan
  • Ssangyong (Kyron, Rexton)
  • Toyota

Fault code P2602 can sometimes be found with other errors. The most common are the following: P2600, P2601, P2603, P261A, P261B, P261C, P261D.


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