Introduction:

The B1728 diagnostic trouble code (DTC) indicates a short to ground in the circuit controlling the "Rear Up" function of the driver's seat. This means the electrical signal intended to raise the rear portion of the driver's seat is inadvertently finding a path to ground before reaching its intended destination, causing a malfunction. Diagnosing and resolving this issue is crucial for restoring full seat functionality and preventing potential electrical damage.

Table: B1728 Seat Driver Rear Up Switch Circuit Short to Ground

Detailed Explanations:

Code Definition: The B1728 code specifically indicates an electrical short to ground in the circuit responsible for raising the rear portion of the driver's seat. The vehicle's computer (often the Body Control Module or Seat Control Module) detects that the electrical signal from the rear up switch is finding an unintended path to ground, preventing the seat from moving as intended. This is a specific fault, distinct from other seat control problems.

Symptoms: The most obvious symptom is the inability to raise the rear of the driver's seat. Other symptoms can include the seat being stuck in its current position, intermittent or erratic seat movement, a blown fuse related to the seat controls, and, in rare cases, a battery drain if the short is severe enough to constantly draw current. Depending on the vehicle's electrical architecture, other seat functions might also be affected.

Damaged Wiring: Damaged wiring is a common cause of the B1728 code. The seat wiring harness is subjected to constant movement and vibration, which can lead to frayed wires, cuts, or pinched sections. Pay particular attention to areas where the harness passes near the seat frame or moving parts, as these are prone to damage. Even seemingly minor damage to the insulation can expose the wire and create a short to ground.

Faulty Switch: A shorted internal contact within the rear up switch can also cause the B1728 code. The switch itself may be malfunctioning, allowing the electrical signal to bypass the intended circuit and go directly to ground. Testing the switch with a multimeter is essential to rule out this possibility.

Damaged Seat Motor: While less common than wiring or switch issues, a short within the seat motor windings can also trigger the B1728 code. The motor itself could be internally shorted, providing a path to ground. This is more likely if the motor has been subjected to excessive stress or wear.

Chafing: Continuous rubbing of the wiring harness against the seat frame or other metal components can wear away the insulation and expose the wires, leading to a short to ground. This is a common problem in vehicles with older wiring harnesses. Carefully inspect the harness for signs of chafing, especially where it comes into contact with metal parts.

Water Intrusion: Water intrusion into the seat control circuit can cause corrosion in connectors and wiring, leading to shorts to ground. Spilled drinks or leaks in the vehicle's roof or windows can introduce moisture into the seat area. Look for signs of corrosion on connectors and wiring.

Connector Issues: Loose or corroded connectors in the seat control circuit can also cause electrical problems, including shorts to ground. Connectors can become loose due to vibration or physical stress, and corrosion can build up over time, especially in humid environments. Ensure all connectors are properly seated and free of corrosion.

Faulty Seat Control Module (SCM): In rare cases, the seat control module (SCM) itself may be faulty, with an internal short circuit causing the B1728 code. This is less likely than wiring or switch issues, but it should be considered if other troubleshooting steps have failed to identify the problem.

Aftermarket Installations: Improperly installed aftermarket seat heaters or other accessories can interfere with the seat wiring and cause a short to ground. If aftermarket accessories have been installed, carefully inspect the wiring to ensure it is properly connected and does not interfere with the original seat wiring.

Visual Inspection: A thorough visual inspection of the seat wiring harness is the first step in troubleshooting the B1728 code. Look for any signs of damage, such as frayed wires, cuts, or pinched sections. Pay close attention to areas where the harness passes near the seat frame or moving parts.

Fuse Check: Check the fuse(s) related to the seat controls. A blown fuse is a strong indicator of a short circuit. Replace the fuse with the correct amperage rating and see if it blows again. If the fuse blows immediately upon replacement, this confirms a significant short circuit.

Switch Testing: Use a multimeter to test the rear up switch for continuity and proper operation. The switch should only show continuity when activated. Check for shorts to ground by measuring the resistance between the switch terminals and the vehicle's chassis ground.

Wiring Continuity Test: Disconnect the seat control module (SCM) and the rear up switch. Use a multimeter to check the continuity of the wiring between the switch connector and the SCM connector. Also, check for shorts to ground on this wire by measuring the resistance between the wire and the vehicle's chassis ground. A low resistance reading indicates a short to ground.

Voltage Test: With the ignition ON and the switch activated, check for voltage at the appropriate terminal of the seat motor. If voltage is present but the motor does not operate, the motor may be faulty. However, if no voltage is present, the problem lies upstream in the circuit (switch, wiring, or SCM).

Component Isolation: Disconnect components one at a time (switch, motor, SCM) to isolate the source of the short. Monitor the circuit with a multimeter to see when the short disappears. For example, if disconnecting the switch causes the short to disappear, the switch is likely the culprit.

Scan Tool Data: If available, use a scan tool to monitor the seat control module data. This may provide additional information about the switch status and circuit conditions. The scan tool may show the switch as being "always on" or "shorted to ground."

Seat Motor Testing: If the wiring and switch are confirmed to be functioning correctly, the seat motor may be faulty. A short within the motor windings can cause the B1728 code. Test the motor's resistance and check for shorts to ground. A low resistance or a reading close to zero indicates a short.

Inspect Connectors: Check all connectors in the seat control circuit for corrosion, loose pins, or damage. Clean or replace connectors as needed. Use electrical contact cleaner to remove corrosion and ensure a good connection.

Consult Wiring Diagrams: Refer to the vehicle's wiring diagrams to identify the specific wiring and components involved in the rear up seat control circuit. Wiring diagrams provide valuable information about wire colors, connector locations, and circuit pathways.

Frequently Asked Questions:

What does B1728 mean? B1728 indicates a short to ground in the circuit controlling the rear up function of the driver's seat. This means the electrical signal is finding an unintended path to ground.

What are the most common causes of B1728? Damaged wiring, a faulty rear up switch, and chafing of the wiring harness are the most common causes.

How do I check for a short to ground? Use a multimeter to measure the resistance between the suspect wire and the vehicle's chassis ground. A low resistance reading indicates a short.

Will a blown fuse always accompany B1728? Not always, but a blown fuse is a strong indicator of a short circuit. A fuse protects the circuit from overcurrent.

Can I fix B1728 myself? If you have basic electrical troubleshooting skills and tools, you may be able to diagnose and repair the problem. However, if you are not comfortable working with electrical systems, it is best to consult a qualified technician.

Does B1728 affect other seat functions? Depending on the vehicle's wiring configuration, other seat functions may be affected. It's best to address the code promptly.

Is B1728 a serious problem? While it may not prevent the vehicle from running, it can be a nuisance and could indicate a more serious electrical issue. A short circuit can potentially lead to a fire.

How much does it cost to fix B1728? The cost to fix B1728 can vary depending on the cause of the problem and the labor rates in your area. Diagnosing and repairing damaged wiring is usually less expensive than replacing a faulty seat motor or control module. Expect to pay anywhere from $100 to $500 or more.

Can aftermarket seat heaters cause B1728? Yes, improperly installed aftermarket seat heaters or other accessories can interfere with the seat wiring and cause a short to ground.

Where is the seat control module located? The location of the seat control module varies depending on the vehicle make and model. It is often located under the driver's seat or in the center console. Consult your vehicle's repair manual for the specific location.

Conclusion:

The B1728 DTC indicates a short to ground within the driver's seat rear up switch circuit, typically caused by damaged wiring or a faulty switch. Thorough troubleshooting using a multimeter and visual inspection of the wiring harness is crucial for identifying and resolving the issue, ensuring proper seat function and preventing potential electrical problems.