Technical Description of OBD-II Trouble Code
The control circuit for Cooling Fan 2 is experiencing low voltage
What does that mean?
This is a generic powertrain diagnostic trouble code (DTC) that applies to all 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 used to cool the engine’s radiator are controlled by the powertrain control module (PCM), which receives input from the engine coolant temperature sensor (ECT). When the ECT reaches a certain temperature, the PCM activates the fans. Once the ECT cools 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, close to the battery voltage. Conversely, when the fans are commanded on, the voltage is near zero. DTC P0693 is triggered when the PCM detects a low voltage when Cooling Fan 2 is off.
Symptoms & Severity of Code
Symptoms of a P0693 code may include:
If the conditions that trigger this DTC are present, there is a high likelihood that the engine may overheat due to the cooling fans not functioning properly. Therefore, caution should be exercised when driving the vehicle, and the issue should be addressed as soon as possible.
Causes
Possible causes for this code to be triggered are:
Diagnostic and Repair Procedures
In my experience, a blown cooling fan fuse is the most common cause of this DTC. Checking the fuse is as simple as locating it, removing it, and visually inspecting it. Usually, you can determine if a fuse is good or not by visual inspection. If the fuse is indeed blown, try replacing it with the correct amperage fuse. If the fuse blows again, the next question to consider is when it blew.
If the fuse failed immediately after replacement, there may be a direct short between the fuse and the relay. If it failed when the engine reached operating temperature, the most likely cause is a frozen cooling fan motor. With the engine and ignition key off, try to spin the fan blades by hand. They should rotate freely. If they do not, the fan motor is frozen and needs to be replaced. If the fuse is intact, the problem is likely the cooling fan relay. If replacing the relay does not resolve the issue, a faulty PCM may be suspected.
Exercise caution when working around components that are not only hot but also in motion.
