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 P261D code may include:
- Malfunction indicator light on
- Overheating
- 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 might be a known problem with a known fix published by the manufacturer and could save you time and money during diagnosis.
Next, locate the B coolant pump (CP-B) 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. Check 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 P261D code returns. If it does not, the connections were likely your problem.
For this particular code, this is the most common area of concern, along with relays/connections to 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 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, 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 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 P261D, 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 correctly.
Other similar coolant pump codes include P2600, P2601, P2602, and P2603.