The diagnostic trouble code (DTC) B1638, "Mirror Driver Right Short To Ground," indicates an electrical fault within the right side mirror control circuit. This means the control circuit, which is responsible for adjusting the mirror's position, has an unintended connection to ground, causing an abnormal flow of electricity. Addressing this issue promptly is crucial to restore proper mirror functionality and prevent potential damage to the vehicle's electrical system.
Understanding the B1638 DTC
| Category | Description | Possible Causes |
|---|---|---|
| Definition | Indicates a short circuit to ground within the right side mirror control circuit. This prevents the mirror from functioning correctly and can potentially damage the mirror motor or associated control modules. | Damaged wiring harness leading to the right mirror; Shorted mirror motor; Faulty mirror control switch; Defective Body Control Module (BCM); Corrosion or damage to connectors in the mirror circuit; Wiring rubbed through insulation. |
| Symptoms | Right side mirror does not move or adjusts erratically; Mirror adjusts slowly or not at all; Blown fuses related to the mirror circuit; Other electrical issues may arise due to the short circuit. | Mirror motor failure; Wiring harness damage; Faulty control switch; BCM malfunction; Fuse failure. |
| Diagnostic Steps | Visual inspection of wiring and connectors; Continuity testing of wiring; Voltage testing of the mirror motor; Resistance testing of the mirror motor; BCM diagnostics; Mirror switch testing. | Multimeter; Wiring diagram; Scan tool; Test light; Basic hand tools. |
| Repair Procedures | Repair or replace damaged wiring; Replace faulty mirror motor; Replace faulty mirror control switch; Replace or reprogram the BCM; Clean corroded connectors; Secure wiring harness to prevent future damage. | Wiring repair kit; New mirror motor; New mirror control switch; BCM reprogramming tools; Connector cleaner; Electrical tape. |
| Related DTCs | B1636 (Mirror Driver Left Short To Ground); Other mirror control circuit codes; Codes related to BCM functionality. | Related wiring issues; BCM problems; Mirror switch malfunctions. |
| Component Location | Right side mirror assembly; Mirror control switch (typically on the driver's side door); Wiring harness running from the BCM to the mirror; BCM (usually located under the dashboard or in the center console). | Visual inspection; Wiring diagrams. |
| Potential Risks | Mirror inoperability; Draining of the battery; Potential damage to the BCM; Risk of fire if the short circuit is severe. | Short circuit left unaddressed; Ignoring warning signs. |
| Tools Needed | Multimeter, wiring diagrams, scan tool (for BCM diagnostics), wire strippers, crimpers, electrical tape, connector cleaner, possibly a new mirror motor and/or switch. | Proper diagnosis is crucial before replacing parts. |
Detailed Explanations
Definition: The B1638 DTC signifies that the electrical circuit controlling the right side mirror's movement has an unintended connection to ground. This "short to ground" creates a path of least resistance, diverting current away from the intended components and potentially causing them to malfunction. The mirror's adjustability is compromised, as the motor receives incorrect or insufficient power.
Symptoms: The most obvious symptom is the right side mirror not moving or adjusting properly. You might also notice erratic movements, a sluggish response, or complete lack of function. A blown fuse in the mirror circuit is another common indicator, as the excessive current flow due to the short can overload the fuse. In some cases, the short circuit can affect other electrical systems, although this is less common.
Diagnostic Steps: The diagnostic process starts with a visual inspection of the wiring and connectors leading to the right side mirror. Look for any signs of damage, such as frayed wires, cracked insulation, or corroded terminals. Next, use a multimeter to perform continuity testing on the wiring to identify the short circuit. Voltage testing can also help determine if the mirror motor is receiving the correct power. If the wiring and motor appear to be in good condition, the BCM and mirror switch should be tested. A scan tool can be used to diagnose the BCM, and the mirror switch can be tested for continuity and proper operation.
Repair Procedures: The repair strategy depends on the root cause of the short circuit. If damaged wiring is found, it should be repaired or replaced using appropriate wiring repair techniques. A faulty mirror motor should be replaced with a new one. If the mirror control switch is defective, it also needs to be replaced. In rare cases, the BCM might be the culprit, requiring replacement or reprogramming. Cleaning corroded connectors is essential for ensuring good electrical contact. Finally, properly securing the wiring harness will help prevent future damage.
Related DTCs: The B1638 code is often accompanied by other DTCs related to mirror control circuits, such as B1636, which indicates a short to ground in the left side mirror circuit. Codes related to BCM functionality may also appear if the BCM is affected by the short circuit. These related codes can provide additional clues about the underlying problem.
Component Location: The right side mirror assembly is obviously located on the right side of the vehicle. The mirror control switch is typically found on the driver's side door, allowing the driver to adjust both mirrors. The wiring harness runs from the BCM to the mirror, and its path can be traced using a wiring diagram. The BCM is usually located under the dashboard or in the center console, although its exact location varies depending on the vehicle make and model.
Potential Risks: Leaving a B1638 code unaddressed can lead to several problems. The inoperable mirror compromises driving safety. The short circuit can drain the battery, especially if it's a continuous short. In severe cases, the excessive current flow can damage the BCM or even create a fire hazard.
Tools Needed: A multimeter is essential for performing continuity and voltage testing. Wiring diagrams are crucial for tracing the wiring harness and identifying the correct wires. A scan tool is needed for diagnosing the BCM. Wire strippers, crimpers, and electrical tape are necessary for repairing damaged wiring. Connector cleaner helps remove corrosion from electrical connectors. Depending on the diagnosis, a new mirror motor and/or switch may also be required.
Frequently Asked Questions
What does B1638 mean? It indicates a short to ground in the right side mirror control circuit. This means the mirror is not functioning correctly due to an electrical fault.
Can I fix B1638 myself? Yes, if you have experience with automotive electrical systems, you can diagnose and repair the problem. However, if you are not comfortable working with electrical systems, it's best to take your vehicle to a qualified mechanic.
What causes a short to ground? A short to ground is typically caused by damaged wiring, such as frayed wires or cracked insulation, that allows the wire to come into contact with the vehicle's chassis. Corrosion and faulty components can also cause shorts.
How do I test for a short to ground? Use a multimeter to perform a continuity test between the circuit and a known good ground. A low resistance reading indicates a short to ground.
Will a blown fuse cause a B1638 code? Yes, a blown fuse in the mirror circuit can be a symptom of a short to ground and can trigger the B1638 code. Replacing the fuse without addressing the underlying short will likely result in the fuse blowing again.
Conclusion
The B1638 DTC signifies a short to ground in the right side mirror control circuit, leading to mirror malfunction and potential electrical damage. Proper diagnosis and repair are essential to restore functionality and prevent further issues; consulting a professional is recommended if you lack experience with automotive electrical systems.