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Technical Description of OBD-II Trouble Code
The circuit controlling the Cooling Fan 2 Relay is experiencing high voltage
What does that mean?
This is a generic powertrain diagnostic trouble code (DTC) that applies to most vehicles manufactured from 1996 onwards. The specific steps for repairing this issue may vary depending on the make and model of the vehicle.
The electric motors that operate the fans responsible for cooling the engine’s radiator are controlled by the powertrain control module (PCM). The PCM turns the fans on and off based on readings from the engine coolant temperature sensor (ECT). When the ECT reaches a certain temperature, the PCM activates the fans. When the ECT cools down to a predetermined temperature, the PCM turns the fans off.
The PCM controls the cooling fans by sending a ground signal to the cooling fan relay. When the fans are not commanded on, the voltage on the signal circuit is high, approximately equal to the battery voltage. Conversely, when the fans are commanded on, the voltage is close to zero. DTC P0694 is triggered when the PCM detects that the voltage remains high when the cooling fan 2 is commanded on.
Symptoms & Severity of Code
Symptoms of a P0694 code may include:
If the cooling fans are not operational, there is a high likelihood of the engine overheating. Therefore, caution should be exercised when driving the vehicle under conditions that can trigger this DTC. It is recommended to have the issue repaired as soon as possible.
Causes
Possible causes for this code to be triggered are:
Diagnostic and Repair Procedures
In my experience, a faulty cooling fan relay is the most common cause of this DTC. One simple way to check the relay is to locate it and visually inspect other relays that are identical to it. Then, switch the two relays. Clear the codes and operate the vehicle. If the code does not reappear, replace the relay. If the code reappears, there may be a potential issue with the PCM.
Note: It is crucial to ensure that the relay being switched is identical in every way. Installing an incorrect relay could cause damage to the PCM. Some relays from Nissan, for example, may appear similar but have slight differences in color and can damage the PCM if plugged into the same socket.
Professional Service
While we always recommend seeking mechanical solutions for this issue, if it is not feasible, we offer the option to permanently delete this specific DTC. All other codes will continue to be addressed. If you are interested in this option, please upload your ECU file to our portal.
