[SOLVED] P1638 Code: Fix Generator ‘f’ Terminal Circuit Conditions With Ease!

The automobile fault code P1638 indicates a problem with the generator (alternator) in your vehicle. The most common symptom is the engine light being illuminated or the service engine soon warning light appearing. The cause of this fault code can be a faulty generator, an open or shorted generator harness, poor electrical connection in the generator circuit, or an issue with the powertrain control module (PCM) programming.

It is important to address this issue promptly as it can affect the charging system of your vehicle. The repair for this fault code involves visually inspecting the wiring harness and connectors, checking for damaged components, and looking for any broken, bent, pushed out, or corroded connector pins. The repair time for this issue is estimated to be around 1.0 hour.

To interpret the fault code, it is recommended to check the “Possible Causes” listed above and perform the necessary inspections and repairs.

Repair Importance Level10.0 (Out of 10)
Estimated Repair TimeApproximately 1.0 hour
Repair Difficulty Level10.0 (Out of 10)

When the engine light is on or the service engine soon warning light is illuminated, it could be a sign of the p1638 fault code.

  • The symptoms of the automobile fault code p1638 include the Engine Light being ON or the Service Engine Soon Warning Light being illuminated.

The automobile fault code p1638 can be caused by a faulty generator, open or shorted generator harness, poor electrical connection in the generator circuit, PCM programming, or a faulty PCM.

  • The fault code P1638 can be caused by the following: – Faulty Generator (Alternator) – Open or shorted Generator harness – Poor electrical connection in the Generator circuit – Powertrain Control Module (PCM) programming – Faulty Powertrain Control Module (PCM)

To fix the automobile fault code p1638, start by visually inspecting the wiring harness, connectors, and components for any damage or corrosion.

  • To fix the automobile fault code p1638, you need to follow these steps: 1.
  • Check the possible causes mentioned above.
  • 2.
  • Visually inspect the wiring harness and connectors related to the fault code.
  • 3.
  • Look for any damaged components.
  • 4.
  • Check for broken, bent, pushed out, or corroded pins in the connectors.
  • 5.
  • Repairing this fault code is estimated to take approximately 1.0 hour.

The factors influencing the cost of diagnosing and fixing the automobile fault code p1638 include the estimated repair time of 1.0 hour and the typical hourly rate charged by auto repair shops, which ranges between $75 and $150.

The P1638 fault code relates to the generator field duty cycle signal circuit in the Powertrain Control Module (PCM).

This circuit is responsible for monitoring the duty cycle of the generator in the vehicle.

When the key is in the RUN position and the engine is OFF, the PCM should detect a duty cycle near 0 percent. However, when the engine is running, the duty cycle should be between 5-100 percent. If the PCM detects an out of range PWM signal during the key ON or RUN tests, it will set the P1638 fault code.

This code triggers the PCM to send a class 2 serial data message to the instrument panel cluster (IPC) to illuminate the charge indicator. In summary, the P1638 fault code indicates an issue with the generator ‘F’ terminal circuit, which can affect the monitoring and adjustment of the generator load on the engine.

It is important to address this issue to ensure proper functioning of the vehicle’s electrical system.

What are the possible causes for the automobile fault code p1638?

If you see the engine light or service engine soon warning light on, the fault code P1638 could be the culprit. This code is often caused by a faulty generator (alternator), an open or shorted generator harness, poor electrical connection in the generator circuit, or issues with the powertrain control module (PCM) programming. To fix this issue, start by visually inspecting the wiring harness and connectors. Look for any damaged components and check for broken, bent, pushed out, or corroded connector pins. Don’t forget to check the possible causes listed above for a more comprehensive solution.

How can I visually inspect the wiring harness and connectors to fix the fault code p1638?

To fix fault code P1638, start by visually inspecting the wiring harness and connectors. Look for any damaged components and check for broken, bent, pushed out, or corroded connector pins. This can help identify any issues with the generator harness or poor electrical connections in the generator circuit. Additionally, check the possible causes listed above, such as a faulty generator or Powertrain Control Module (PCM) programming. Taking these steps can help resolve the issue and turn off the engine light or service engine soon warning light.

What should I look for when checking for damaged components and connector’s pins to resolve the fault code p1638?

When troubleshooting the fault code P1638, which is indicated by the Engine Light or Service Engine Soon Warning Light being ON, it is important to check for damaged components and connector’s pins. This fault code can be caused by a faulty generator (alternator), an open or shorted generator harness, poor electrical connection in the generator circuit, or issues with the Powertrain Control Module (PCM) programming. To resolve this issue, visually inspect the wiring harness and connectors, paying close attention to any signs of damage such as broken, bent, pushed out, or corroded connector’s pins.

p1638 error fault code explained

If your engine light is on and you suspect a faulty generator, there are a few things you can do. First, visually inspect the wiring harness and connectors for any damage. Check for broken, bent, pushed out, or corroded pins on the connectors.

This will help you identify any issues and determine the best course of action.

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