P1633 Ford– Meaning, Causes, Symptoms, & Fixes

Your Ford has many codes which can come up when starting it, idling or accelerating. These codes could be related to the engine, the emission systems, or the transmission. Knowing what each code means helps you decide whether to fix it immediately or run your errands first. If the code is associated with a vital component in your car, you should fix it immediately. Code P1633 is one of those codes that can appear at any time. You might run into trouble if you don’t know what it means or how to resolve it. Luckily, we will explain everything you need to know about code P1633 in your Ford.

 Code P1633 meaning

There is a circuit in your Ford called the Keep Alive Memory Circuit (KAMC). This circuit supplies an optimal voltage to the power control module (PCM). Given enough voltage, the PCM continuously records data about your Ford’s drive information. Such data could describe idle control, transmission control, fuel control, etc. So, if such voltage falls below normal, the PCM will not be able to perform that function. This will result in code P1633 being shown in the OBD II system.

 Symptoms of code P1633

 Code P1633 is not associated with many symptoms. However, if you notice the following symptoms in your Ford, there is a high chance that code P1633 will appear.

 1. Check engine light comes on

 The check engine light always comes on when the PCM detects a problem in your Ford. Therefore, it won’t be surprising to observe it when code P1633 exists. However, since it’s a symptom of many other problems, you shouldn’t rely on it completely.

2. The Ford takes a long time to start

 If code P1633 is present, you will notice that your Ford vehicle takes a long time to start after shutting off. For instance, it will take around ten starts to come on. The PCM will reset to factory programming whenever the KAMC voltage falls below the optimal level.

 Code P1633 causes

 Many things can cause the error code P1633 in your Ford vehicle. These things are mostly related to the KAMC. Below are its leading causes.

1. Bad battery

 As already indicated, the KAMC receives voltage from the battery. If the battery goes bad, the voltage that reaches this circuit will be low, resulting in code P1633. Your car’s battery can get defective due to old age, overheating, short circuits and overcharging.

2. Faulty fuse

There is a fuse that prevents excess current from damaging the PCM. If this fuse gets burnt, no voltage will reach the PCM. When that happens, the PCM will not store the drive data; instead, code P1633 is produced.

3. Burned clutch relay

 The clutch relay supplies electric current to the clutch and air conditioner (AC)compressor. Like any other component, the clutch relay can wear or burn out. This relay is linked to the fuse between the KAMC and the PCM. It draws excessive current from the fuse when it gets faulty. This will reduce the amount of voltage reaching the PCM. As a result, the PCM will fail to record the live drive data and code P1633 is shown in the OBD II system.

 4. Damaged compressor clutch coil

 A damaged compressor clutch coil can also cause code P1633 in your Ford. The coil is responsible for creating an electromagnetic field needed by the clutch to move. As such, it needs an electric current to work. The clutch relay supplies the electric current. Therefore, excess current is drawn from the fuse if the clutch coil goes bad. Hence the PCM will be deprived of the necessary voltage to record drive information.

 5. Issue with the cables

 Your Ford has cables which supply electric voltage to the KAMC and the PCM. If one of these cables malfunctions or gets loose low, electric current will not reach the two components. Things such as old age or electric shorts can damage the cables. But sometimes, they are loose at the battery terminals, the KAMC or the PCM.

6. Malfunctioned PCM

 In some instances, the PCM itself can malfunction. This happens when it develops bugs, which make it not record the drive data. Exposure to water, voltage overloads and excess vibrations can also make the PCM go bad. So, if you have received code P1633, there is a likelihood that the PCM has malfunctioned.

 How to fix code P1633?

 You can fix code P1633 by diagnosing its cause and resolving it. Depending on the extent of the damage, you can either replace or repair the affected part. Here is what you can do.

1. Replace the battery

The only option available when it comes to a bad battery is to replace it. However, you first have to diagnose that it is the one causing code P1633 in your Ford. You can do so by checking its voltage using a multimeter. If your Ford’s voltage is below 12.6 volts when the engine is off, it is faulty and needs to be replaced with a new one. Fortunately, replacing a car battery is pretty straightforward. You only have to disconnect the cables and remove the battery from its compartment.

 2. Replace the fuse

If the battery is fine, proceed to check the fuse. Like the battery, you can diagnose a faulty fuse using a multimeter. To do so, set the multimeter to measure electric resistance and place its positive and negative probes at each end of the fuse. The fuse is bad if the multimeter gives an “OL” reading. Unfortunately, a lousy fuse cannot be repaired, and the only way to get rid of code p1633 is by replacing it.

 3. Fix the cables

Manually examining if the wires have an issue can be tedious. This is because you have to determine if they are broken, shorted or corroded. You can start by checking if they are loose at the KAMC or the battery terminals. If they are not firm, tightening them will fix code P1633. However, if the code persists, you should check if the battery terminals are corroded. If the terminals have a white substance, it means they are corroded. Luckily, with a screwdriver, you can scratch off the white substance. On the other hand, shorted cables will have to be replaced with new ones.

 4. Replace the clutch relay

 The clutch relay is a small component located in the engine compartment. When the clutch relay gets faulty, the compressor will fail to supply cold air. You will also notice the air conditioner light blinking. High voltage, moisture and excess temperature can make the clutch relay bad. The bad news is that a damaged clutch relay is hard to repair; hence the only option is to replace it.

 5. Fix the clutch coil

 Using a multimeter, you can find out if the clutch coil is damaged. All you have to do is connect its two terminals to the multimeter, turn it on, and record the reading. You have a faulty clutch coil if the multimeter reads less than 2 ohms or above 5 ohms. Although a lousy clutch coil can be repaired, the process is technical, so it needs a professional to do it.

 6. Reboot the PCM

 The bugs in the PCM can easily be eliminated by rebooting the system. Your Ford manual can guide you on how to do it. However, if the PCM is damaged, it must be repaired to eliminate the error code P1633. Sadly, it’s a tedious and technical process; hence you may want to consult a professional.

Should you be worried when you get code P1633?

Code P1633 is not one of those codes that should give you a rough day. In many cases, you may not even realize that there is a problem with your Ford. However, if your car starts taking too long to start, you should fix it immediately.

 How much does it cost to diagnose and fix code P1633?

 If you don’t have the technical skills or time to diagnose and fix what is causing code P1633, you should visit a repair shop. The cost of diagnosing it is around an hour of labor. Fixing cost will depend on your Ford’s model, the damage’s extent and the cost of the part that needs to be replaced. But in most cases, the price will range from $75 to $200.


 In summary, code P1633 is not a severe issue. It is a code that indicates a problem with the KAMC. Some things that can cause it are a faulty battery, an issue with the cables, a bad clutch relay, burned clutch coil, and a problem with the PCM. These things can easily be fixed when you have the technical know-how and time. Otherwise, you should take your car to a mechanic shop to fix code P1633.

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