Introduction:
The B1628 diagnostic trouble code (DTC) indicates a problem within the vehicle's Park/Reverse/Neutral/Drive/Low (PRNDL) switch circuit, specifically an open circuit in the reverse gear input. This means the vehicle's computer (PCM/BCM) isn't receiving the expected signal when the transmission is placed in reverse. This can lead to various issues, including the reverse lights not functioning, the backup camera failing to activate, and potentially affecting the transmission's electronic control.
Comprehensive Table: B1628 PRNDL Reverse Input Open Circuit
| Category | Description | Potential Causes |
|---|---|---|
| Definition | B1628 indicates an open circuit in the reverse gear input signal of the PRNDL switch. The PCM/BCM is not receiving the voltage signal it expects when the transmission is in reverse. | Damaged or disconnected wiring to the PRNDL switch; Faulty PRNDL switch; Corroded or loose connectors; Blown fuse related to the reverse light circuit; PCM/BCM failure (rare) |
| Symptoms | Reverse lights not working; Backup camera not activating; Transmission shift issues (in rare cases); Diagnostic Trouble Code (DTC) B1628 stored in PCM/BCM; Warning lights illuminated on the dashboard (e.g., check engine light). | |
| Possible Causes: Wiring & Connections | Issues related to the wiring and connections in the reverse input circuit. | Open circuit in the reverse input wire: A break in the wire prevents the signal from reaching the PCM/BCM.; Short to ground: The wire is touching a grounded metal surface, diverting the signal.; Corroded or loose connectors: Corrosion or looseness in the connectors disrupts the signal flow.; Damaged wiring insulation: Damaged insulation allows the wire to short or become open. |
| Possible Causes: PRNDL Switch | Problems with the PRNDL switch itself. | Faulty PRNDL switch: The switch is not properly sending the reverse signal when in reverse.; Internal short or open circuit within the switch: The switch's internal components are damaged, preventing signal transmission.; Misalignment of the PRNDL switch: The switch is not properly aligned with the transmission linkage, resulting in incorrect signal output.; Water intrusion: Water damage can cause corrosion and malfunction of the switch's internal components. |
| Possible Causes: Fuses & Relays | Issues with fuses and relays related to the reverse light circuit. | Blown fuse: A blown fuse interrupts the power supply to the reverse light circuit.; Faulty relay: A faulty relay prevents the power from reaching the reverse lights or the PRNDL switch. |
| Diagnostic Tools | Tools used to diagnose the B1628 code. | Multimeter: Used to check voltage, continuity, and resistance in the circuit.; Scan tool: Used to read DTCs, view live data, and perform actuator tests.; Wiring diagram: Used to trace the circuit and identify potential problem areas.; Test light: Used to check for power and ground in the circuit. |
| Diagnostic Steps | Steps to diagnose the B1628 code. | Verify the code: Confirm the B1628 code is present using a scan tool.; Inspect the wiring and connectors: Visually inspect the wiring and connectors for damage, corrosion, or looseness.; Check the fuse: Check the fuse for the reverse lights to see if it is blown.; Test the PRNDL switch: Use a multimeter to test the PRNDL switch for proper operation.; Check the wiring for continuity: Use a multimeter to check the wiring for continuity between the PRNDL switch and the PCM/BCM.; Check for voltage: Verify the presence of voltage at the PRNDL switch and the reverse lights.; Inspect the reverse light bulbs: Confirm that the reverse light bulbs are not burnt out. |
| Repair Procedures | Procedures to repair the B1628 code. | Repair or replace damaged wiring: Repair any damaged wiring or replace it if necessary.; Clean or replace corroded connectors: Clean any corroded connectors or replace them if necessary.; Replace the PRNDL switch: Replace the PRNDL switch if it is faulty.; Replace the fuse: Replace the blown fuse with a new one of the correct amperage.; Repair or replace the PCM/BCM: Repair or replace the PCM/BCM if it is faulty (rare). |
| Related DTCs | Other DTCs that may be related to the B1628 code. | B1629 - PRNDL Reverse Input Circuit High; Other PRNDL switch-related codes; Transmission-related codes. |
| Impact on Vehicle Operation | How the B1628 code affects vehicle operation. | Reverse lights inoperative: The reverse lights will not turn on when the vehicle is in reverse.; Backup camera inoperative: The backup camera will not activate when the vehicle is in reverse.; Potential shift issues: In rare cases, the B1628 code can affect the transmission's electronic control, leading to shift issues.; Safety concerns: The absence of reverse lights can increase the risk of accidents when backing up. |
| Preventative Maintenance | Measures to prevent the B1628 code. | Regularly inspect wiring and connectors: Inspect the wiring and connectors for damage, corrosion, or looseness.; Protect wiring from damage: Protect the wiring from damage by using wire looms and routing the wiring away from sharp edges.; Avoid water intrusion: Avoid water intrusion into the PRNDL switch by sealing any openings.; Properly maintain the transmission: Properly maintain the transmission to prevent issues that could damage the PRNDL switch. |
| Difficulty Level of Repair | Difficulty of repairing the B1628 code. | Low to Moderate: Simple wiring repairs and fuse replacements are generally considered low difficulty. Replacing the PRNDL switch or diagnosing complex wiring issues can be more challenging and require specialized tools and knowledge. |
| Estimated Repair Cost | Estimated cost to repair the B1628 code. | $50 - $500: The cost of repair will vary depending on the cause of the problem. A simple fuse replacement may cost only a few dollars, while replacing the PRNDL switch can cost several hundred dollars. Labor costs will also vary depending on the shop and the complexity of the repair. |
Detailed Explanations:
Definition:
The B1628 code is a specific diagnostic code that indicates the vehicle's computer (Powertrain Control Module or Body Control Module) is not receiving the correct signal from the PRNDL (Park/Reverse/Neutral/Drive/Low) switch when the transmission is placed in reverse. This signifies an open circuit, meaning the electrical pathway is broken, preventing the signal from reaching its destination.
Symptoms:
The most common and noticeable symptom is the reverse lights not working. Because the PCM/BCM doesn't receive the signal confirming the vehicle is in reverse, it won't activate the reverse lights. Similarly, the backup camera might not activate as it relies on the same signal. In rare cases, the code can cause transmission shift issues, although this is less common. The check engine light or other warning lights will likely illuminate on the dashboard, and the B1628 DTC will be stored in the vehicle's computer.
Possible Causes: Wiring & Connections:
An open circuit in the reverse input wire is a primary suspect. This means a break in the wire prevents the signal from traveling. A short to ground occurs when the wire touches a grounded metal surface, diverting the signal. Corroded or loose connectors disrupt the signal flow due to poor electrical contact. Damaged wiring insulation can expose the wire, leading to shorts or opens.
Possible Causes: PRNDL Switch:
A faulty PRNDL switch is a common cause. The switch itself might be malfunctioning, failing to send the reverse signal when the gear selector is in reverse. An internal short or open circuit within the switch prevents proper signal transmission. Misalignment of the PRNDL switch with the transmission linkage can also result in incorrect signal output. Water intrusion can corrode the switch's internal components, leading to malfunction.
Possible Causes: Fuses & Relays:
A blown fuse in the reverse light circuit is a straightforward cause. A blown fuse interrupts the power supply necessary for the reverse lights and potentially the PRNDL switch's signal. A faulty relay, if one is present in the circuit, can also prevent power from reaching the reverse lights or the PRNDL switch.
Diagnostic Tools:
A multimeter is crucial for checking voltage, continuity, and resistance in the circuit. A scan tool is used to read the B1628 DTC and view live data related to the PRNDL switch. A wiring diagram helps trace the circuit and identify potential problem areas. A test light can be used to quickly check for power and ground at various points in the circuit.
Diagnostic Steps:
- Verify the code: Confirm the B1628 code is present using a scan tool.
- Inspect the wiring and connectors: Visually inspect all wiring and connectors related to the PRNDL switch and reverse lights for any signs of damage, corrosion, or looseness.
- Check the fuse: Check the fuse specifically for the reverse lights to see if it's blown. Refer to the vehicle's owner's manual for fuse location.
- Test the PRNDL switch: Using a multimeter and the vehicle's wiring diagram, test the PRNDL switch for proper operation in the reverse position. Check for continuity and voltage output.
- Check the wiring for continuity: Use a multimeter to check for continuity between the PRNDL switch and the PCM/BCM. This verifies the wiring is intact.
- Check for voltage: Verify the presence of voltage at the PRNDL switch and the reverse lights when the vehicle is in reverse.
- Inspect the reverse light bulbs: Confirm that the reverse light bulbs are not burnt out, although this is less likely to be the sole cause of a B1628 code.
Repair Procedures:
Repair or replace damaged wiring: Repair any frayed, cut, or otherwise damaged wiring. If the damage is extensive, replace the entire wire. Clean or replace corroded connectors: Clean corroded connectors with electrical contact cleaner. If the corrosion is severe, replace the connector. Replace the PRNDL switch: If the PRNDL switch is determined to be faulty, replace it with a new one. Ensure the new switch is properly aligned. Replace the fuse: Replace a blown fuse with a new fuse of the correct amperage. Repair or replace the PCM/BCM: This is a last resort. PCM/BCM failure is rare, and it should only be considered after all other possibilities have been ruled out.
Related DTCs:
B1629 - PRNDL Reverse Input Circuit High indicates a high voltage situation in the same circuit. Other PRNDL switch-related codes might also be present, pointing to broader issues with the switch. In rare cases, transmission-related codes could accompany B1628, suggesting a potential connection to the transmission's electronic controls.
Impact on Vehicle Operation:
The most immediate impact is that the reverse lights will not turn on when the vehicle is in reverse. This is a safety concern. The backup camera will also be inoperative. While less common, the B1628 code can affect the transmission's electronic control, potentially leading to shift issues. The lack of reverse lights poses significant safety concerns as it reduces visibility when backing up.
Preventative Maintenance:
Regularly inspect wiring and connectors for any signs of damage, corrosion, or looseness. Protect wiring from damage by using wire looms and routing the wiring away from sharp edges and heat sources. Avoid water intrusion into the PRNDL switch area. Properly maintain the transmission to prevent issues that could indirectly affect the PRNDL switch's operation.
Difficulty Level of Repair:
Repairing the B1628 code ranges from low to moderate difficulty. Replacing a blown fuse or cleaning a corroded connector is generally considered low difficulty. Replacing the PRNDL switch or diagnosing complex wiring problems can be more challenging and might require specialized tools and knowledge.
Estimated Repair Cost:
The estimated repair cost varies significantly, ranging from $50 to $500 or more. A simple fuse replacement might cost only a few dollars. Replacing the PRNDL switch can cost several hundred dollars, including parts and labor. Complex wiring repairs can also increase the cost.
Frequently Asked Questions:
What does the B1628 code mean? It means there's an open circuit in the reverse gear input signal of your vehicle's PRNDL switch, preventing the computer from knowing when you're in reverse.
Will my car still drive with a B1628 code? Yes, your car will generally still drive, but your reverse lights and backup camera may not work, and in rare cases, there could be transmission issues.
Can I fix the B1628 code myself? It depends on your mechanical skills. Simple fixes like replacing a fuse or cleaning a connector are doable for many, but more complex repairs might require professional assistance.
Is it dangerous to drive with the B1628 code? The primary danger is the lack of reverse lights, which can increase the risk of accidents when backing up.
How do I find the PRNDL switch in my car? The PRNDL switch is usually located on the transmission, where the shift linkage connects. Consult your vehicle's repair manual for the specific location.
Where can I find a wiring diagram for my car? Wiring diagrams can often be found in your vehicle's repair manual or online through subscription-based services.
How do I check a fuse? Visually inspect the fuse for a broken filament. You can also use a multimeter to check for continuity across the fuse terminals.
Conclusion:
The B1628 PRNDL Reverse Input Open Circuit code indicates a problem with the reverse signal in your vehicle's transmission system. Thorough diagnosis, starting with simple checks like fuses and wiring, is crucial for effective repair and restoring proper functionality to your reverse lights and related systems.