Technical Description of OBD-II Trouble Code
Circuit for Cooling Fan Speed Sensor
This powertrain code (DTC) is a generic OBD-II code that applies to all vehicle makes and models (1996-newer). However, the specific repair steps may vary depending on the model.
What does that mean?
Some vehicles have a sensor at the end of the cooling fan that detects movement during vehicle operation. This sensor is used to determine if the fan is running on a fan clutch equipped vehicle or to verify the fan speed commanded by the Powertrain Control Module (PCM) or Engine Control Module (ECM) matches the actual fan speed detected on an electric fan equipped vehicle.
The sensor used is a 3-wire, hall effect sensor that uses a 5-volt reference source from the PCM, a ground wire, and a signal wire to the PCM to determine fan speed. In the case of the P0526 DTC, it means the PCM/ECM has detected a fault with the sensor or wiring.
Note: Be cautious not to touch an electric fan as it may turn on even when the vehicle is not operating. This code is similar to P0527, P0528, and P0529.
Symptoms
Symptoms of a P0526 DTC may include:
Causes
Potential causes of a P0526 code include:
Possible Solutions
Fan clutch equipped – Visually check if the fan is spinning while the engine is operating. If the fan is not spinning, this may be caused by a broken accessory belt or a failed fan clutch assembly. Replace the accessory belt, fan clutch assembly, or cooling fan.
Electrical fan equipped – Visually check if the fan is turning on and off when the PCM/ECM commands the fan to operate at certain temperatures. The fan may be automatically turned on when the air conditioner is turned on. If the fan is not operating, check the electrical harness connector, fuses, or relays that control the electric fan. Some fans may be turned on using an on/off relay or activated by Pulse Width Modulation (PWM) with variable speed fans. Repair the electrical fan circuit, replace the electric fan assembly, motor, or fan module if equipped.
Cooling fan sensor harness – Check for loose connections and damaged wiring that may have come in contact with the cooling fan. Unplug the cooling fan sensor connector and the connector at the PCM, and check for resistance using a Digital Volt Ohm Meter (DVOM) with leads at each end of the power wire, signal wire, and ground (if connected to the PCM/ECM). Some vehicle manufacturers have issued a Technical Service Bulletin (TSB) for replacement of the sensor wiring harness. Replace or repair the harness.
PCM/ECM – Unplug the harness connector at the cooling fan sensor with the vehicle key on/engine off. Check for a 5-volt reference source from the PCM using a wiring diagram for reference, with the DVOM set to the volts scale, with the positive lead on the power wire and the negative lead to a known good ground. Check for ground using the DVOM positive lead connected to a known good power source (battery positive) and the negative lead at the harness ground wire. Replace the PCM/ECM if the reference voltage is not being supplied.
Cooling fan speed sensor – Disconnect the harness connector from the sensor and test for continuity using the DVOM set to the ohms scale between the power and ground wires. There should be resistance present between the two wires.
The Signal wire may only be tested during actual fan operation by back probing the harness connector with the DVOM set to the volts scale or a graphing multimeter with the positive lead on the signal wire and the negative lead to a known good ground, since the hall effect sensor used operates by creating a magnetic field that changes voltage while the fan is spinning. As fan speed increases, the voltage should also increase. It may be necessary to monitor the fan speed using an advanced scan tool to verify that the actual fan speed matches the commanded fan speed. Replace the cooling fan speed sensor if the part has failed.
