P1638 code — how to fix error fast

The code P1638 can be one of the biggest unpleasant surprises you can live through with your car, and to put it straight out there, it has to do with the alternator and the charging system of the battery. However, it takes having an in-depth understanding of the P1638 code meaning so you can rest assured that the code is properly dealt with.

We know how confusing and bothersome it can be, which is why our team of automotive experts has decided to help. This guide will lay out all the important pieces of advice on detecting the root cause of the code, applying an appropriate diagnostic method, and solving it with a proper fix.

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What does the P1638 code mean?

The P1638 code refers to a malfunction in the generator or alternator’s control circuit. When this code appears, it means that the powertrain control module (PCM) has detected an abnormal voltage level or an open circuit in the generator or alternator control circuit.

The consequences of the code include poor engine performance, rough idling, and difficulty starting the vehicle. If left unchecked, it can lead to a dead battery and a non-functional vehicle.

What causes the P1638 code?

The list of potential causes of this code is surprisingly high, which is why it takes knowing about all of these to properly solve the issue and clear the code. Here’s a brief overview of each of the potential reasons behind this code:

Faulty alternator

The alternator is a crucial component of your vehicle’s electrical system. It converts mechanical energy into electrical energy and charges the battery while the engine is running. If the alternator is faulty, it can cause the P1638 code to appear. Signs of a faulty alternator include dimming headlights, a dead battery, and a warning light on the dashboard.

Bad battery

A bad battery can also trigger the code. A weak or dead battery can cause the alternator to overwork, leading to a malfunction in the control circuit. Signs of a bad battery include difficulty starting the vehicle, dimming lights, and a bloated or corroded battery.

Defective wiring harness

A defective wiring harness can cause a short circuit in the control circuit, leading to this code. Signs of a faulty wiring harness include flickering lights, a dead battery, and a burning smell.

Blown fuse

A blown fuse in the generator or alternator control circuit can cause the P1638 code to appear. Signs of a blown fuse include non-functional electrical components and a warning light on the dashboard.

Malfunctioning PCM

A malfunctioning PCM can also trigger the code due to a software malfunction or a hardware failure. Signs of a malfunctioning PCM include poor engine performance, difficulty starting the vehicle, and a warning light on the dashboard.

Which car models does the P1683 code affect the most?

The P1638 code can affect any car model that has an alternator or generator control circuit. However, some car models are more prone to the code than others. These mostly include models with poorly-designed electrical systems, such as the following vehicles:

• Nissan Altima: These models have been known to experience issues with the generator control circuit, which can trigger the P1638 code.
• Buick LeSabre:: Some owners of this model have reported this code caused by faulty generator control modules.
• Honda Civic:: Issues with the voltage regulator in these models can cause the generator control circuit to malfunction, leading to the code’s activation.

How to diagnose the P1683 code

Diagnosing this code mostly includes checking the electrical systems of the vehicle. This mostly includes checking the charge of the key electrical system components, but here’s a list of the main diagnostic methods in further detail:

Check the battery

The first step is to check the battery’s voltage level. A weak or dead battery can cause this code to appear. Use a multimeter to measure the battery’s voltage level.

Check the alternator

The second step is to check the alternator’s output voltage. A faulty alternator can cause the P1638 code to appear. Use a multimeter to measure the alternator’s output voltage.

Check the wiring harness

The third step is to check the wiring harness for any damage or loose connections. A damaged wiring harness can cause a short circuit in the control circuit, leading to the code.

Look for blown fuses

The fourth step is to check the fuses in the generator or alternator control circuit. A blown fuse can cause the code to activate.

How to fix the P1683 code

There are several ways of fixing the code P1683 code and it all depends on the exact reason behind the code. You can therefore apply one of the following solutions to fix and remove the code:

Fixing a faulty alternator

If the alternator is faulty, replace it with a new one. The cost of a new alternator varies depending on the make and model of your vehicle.

Fixing a bad battery

If the battery is weak or dead, replace it with a new one. The cost of a new battery varies depending on the make and model of your vehicle.

Fixing a defective wiring harness

If the wiring harness is defective, repair or replace it. The cost of repairing or replacing a wiring harness varies depending on the extent of the damage.

Fixing a blown fuse

If the fuse is blown, replace it with a new one. The cost of a new fuse depends on the make and model of your vehicle.

Fixing a faulty PCM

If the PCM is malfunctioning, replace it with a new one. The cost of a new PCM could go from $500 to $1500 and even higher depending on your vehicle model.

How to prevent the P1683 code

Once you’ve sorted out the issue with this code, it’s best to stick with some preventive measures to make sure that the code doesn’t happen again anytime soon. You can do this by looking at the electrical system of your vehicle, and here are some steps to follow:

• Check the battery and its charge
• Make sure that the alternator is working properly
• Measure the voltage of the battery and its charging system
• Be aware of the warning signs of generator circuit damage like dim lights or inoperable power windows

If you take these steps and combine them with the listed methods of fixing and repairing the issue behind this code, you should never encounter it again.

Our take

Overall, the P1638 code is among the most common issues that car owners may face. If you follow the steps outlined in this article, you can diagnose, fix, and prevent the P1638 code from appearing again, so we hope that our team was able to help you out with it.