The P0705 diagnostic trouble code (DTC) indicates a problem with the transmission range switch circuit. This switch, also known as the neutral safety switch or park/neutral position (PNP) switch, is crucial for informing the vehicle's computer (PCM/TCM) about the gear selector lever's position. A malfunctioning or improperly adjusted switch can lead to various drivability issues, including starting problems, incorrect gear selection, and even damage to the transmission.
Diagnosing and resolving a P0705 code requires understanding the switch's function, the circuit it's a part of, and common failure points. A systematic approach to troubleshooting, involving visual inspection, electrical testing, and accurate diagnosis, is essential for a successful repair.
| Component/Aspect | Description | Potential Issues/Solutions |
|---|---|---|
| Transmission Range Switch (TRS) | A mechanical switch that sends signals to the PCM/TCM indicating the gear selector lever's position (Park, Reverse, Neutral, Drive, Low, etc.). Often mounted on the transmission case or shift linkage. | Physical Damage: Cracked housing, bent linkage. Solution: Replace the switch. Contamination: Grease, dirt, or debris interfering with switch contacts. Solution: Clean or replace the switch. Wear and Tear: Contacts worn or corroded. Solution: Replace the switch. Misalignment: Switch not properly aligned with the shift linkage. Solution: Adjust the switch according to manufacturer's specifications. |
| Wiring Harness & Connectors | The electrical wiring and connectors that connect the TRS to the PCM/TCM. | Corrosion: Corrosion on connector pins. Solution: Clean or replace corroded connectors. Damaged Wiring: Frayed, cut, or shorted wires. Solution: Repair or replace damaged wiring. Loose Connections: Loose or improperly seated connectors. Solution: Secure connectors properly. Open Circuits: Broken wires preventing signal transmission. Solution: Repair or replace open circuits. |
| PCM/TCM (Powertrain Control Module/Transmission Control Module) | The vehicle's computer that receives signals from the TRS and controls transmission operation. | Internal Failure: Rare, but possible. Solution: Test PCM/TCM functionality; potentially replace and reprogram. Software Glitch: Rare, but possible. Solution: Check for PCM/TCM software updates. |
| Shift Linkage | The mechanical linkage connecting the gear selector lever to the transmission. | Loose or Damaged Linkage: Excessive play or binding in the linkage. Solution: Repair or replace worn or damaged linkage components. Improper Adjustment: Linkage not properly adjusted. Solution: Adjust shift linkage to factory specifications. |
| Symptoms Associated with P0705 | Observable issues resulting from a faulty TRS circuit. | No Start Condition: Engine will not start in Park or Neutral. Solution: Verify TRS signal for Park/Neutral. Engine Starts in Gear: Engine starts in any gear. Solution: Verify TRS prevents starting in gears other than Park/Neutral. Incorrect Gear Indication: Dashboard gear indicator does not match the actual gear selected. Solution: Verify TRS signal matches gear lever position. Transmission Shifting Problems: Erratic shifting, failure to shift, or limp mode. Solution: Verify TRS signal is consistent and accurate during gear changes. Reverse Lights Not Working: Reverse lights do not illuminate when in Reverse. Solution: Verify TRS signal activates reverse lights. Cruise Control Malfunction: Cruise control may not engage or disengage properly. Solution: Verify TRS signal is consistent and accurate. |
| Diagnostic Tools & Procedures | Tools and methods used to diagnose the P0705 code. | OBD-II Scanner: Used to read and clear diagnostic trouble codes. Solution: Use scanner to confirm P0705 code and check for other related codes. Multimeter: Used to test voltage, resistance, and continuity in the TRS circuit. Solution: Use multimeter to check wiring, connectors, and switch functionality. Wiring Diagrams: Essential for tracing circuits and identifying components. Solution: Consult vehicle-specific wiring diagrams to identify circuit components and test points. Visual Inspection: Check for obvious signs of damage or corrosion. Solution: Visually inspect the TRS, wiring, and connectors for damage. * Component Testing: Testing the TRS to verify it functions correctly. Solution: Use a multimeter to test the switch's resistance in each gear position. |
| Common Causes | Frequently encountered reasons for the P0705 code. | Faulty Transmission Range Switch: Most common cause. Solution: Replace the TRS. Misadjusted Transmission Range Switch: Switch not properly aligned. Solution: Adjust the TRS. Wiring Problems: Damaged or corroded wiring or connectors. Solution: Repair or replace wiring and connectors. Shift Linkage Problems: Loose or damaged shift linkage. Solution: Repair or replace shift linkage components. |
| Troubleshooting Steps | A structured approach to resolving the P0705 code. | 1. Verify the Code: Confirm the P0705 code is present using an OBD-II scanner. 2. Visual Inspection: Inspect the TRS, wiring, and connectors for damage. 3. Check Shift Linkage: Inspect and adjust the shift linkage as needed. 4. Test the TRS: Use a multimeter to test the TRS in each gear position. 5. Check Wiring: Test the wiring and connectors for continuity, voltage, and shorts. 6. Consult Wiring Diagram: Refer to the vehicle's wiring diagram for proper circuit tracing. 7. Replace Components: Replace faulty components as identified through testing. 8. Clear Codes and Retest: Clear the DTCs and retest the system to ensure the problem is resolved. |
| Potential Repair Costs | Estimated expenses associated with resolving the P0705 code. | Transmission Range Switch Replacement: $50 - $300 (parts and labor). Wiring Repair: $50 - $200 (parts and labor). Shift Linkage Repair: $50 - $250 (parts and labor). PCM/TCM Replacement (Rare): $500 - $1500 (parts and labor, including reprogramming). |
| Related Diagnostic Trouble Codes | Other DTCs that may be present alongside P0705. | P0706: Transmission Range Sensor Circuit Range/Performance. P0707: Transmission Range Sensor Circuit Low Input. P0708: Transmission Range Sensor Circuit High Input. P0709: Transmission Range Sensor Circuit Intermittent. |
Detailed Explanations
Transmission Range Switch (TRS): The TRS, often referred to as the neutral safety switch or park/neutral position (PNP) switch, is a crucial component that tells the vehicle's computer the position of the gear selector. This information is used for several functions, including starting the engine, engaging reverse lights, and controlling transmission shifting. It's typically located on the transmission case or shift linkage.
Wiring Harness & Connectors: The wiring harness and connectors are the electrical pathways that connect the TRS to the PCM/TCM. These components are susceptible to corrosion, damage, and loose connections, which can disrupt the signal flow and trigger the P0705 code. Thorough inspection and testing of these components are essential during troubleshooting.
PCM/TCM (Powertrain Control Module/Transmission Control Module): The PCM/TCM is the vehicle's computer that processes the signals from the TRS and controls various functions, including engine and transmission operation. While less common, internal failures or software glitches in the PCM/TCM can contribute to the P0705 code.
Shift Linkage: The shift linkage is the mechanical connection between the gear selector lever and the transmission. Problems with the shift linkage, such as looseness, damage, or improper adjustment, can prevent the TRS from accurately sensing the gear position, leading to the P0705 code.
Symptoms Associated with P0705: The symptoms associated with the P0705 code can vary depending on the severity of the problem. Common symptoms include a no-start condition, the engine starting in gear, incorrect gear indication on the dashboard, transmission shifting problems, non-functional reverse lights, and cruise control malfunctions.
Diagnostic Tools & Procedures: Diagnosing the P0705 code requires a systematic approach using various tools and procedures. An OBD-II scanner is used to read and clear DTCs, while a multimeter is used to test voltage, resistance, and continuity in the TRS circuit. Wiring diagrams are essential for tracing circuits and identifying components.
Common Causes: The most common cause of the P0705 code is a faulty transmission range switch. Other common causes include a misadjusted TRS, wiring problems, and shift linkage issues. Identifying the root cause is crucial for a successful repair.
Troubleshooting Steps: A structured troubleshooting approach is essential for resolving the P0705 code. This involves verifying the code, performing a visual inspection, checking the shift linkage, testing the TRS, checking the wiring, consulting wiring diagrams, replacing faulty components, and clearing codes and retesting.
Potential Repair Costs: The cost of repairing the P0705 code can vary depending on the cause and the extent of the damage. Replacing the TRS is typically the most common repair, while more complex repairs, such as wiring repairs or PCM/TCM replacement, can be more expensive.
Related Diagnostic Trouble Codes: Several other DTCs may be present alongside the P0705 code, indicating related issues with the transmission range sensor circuit. These codes can provide valuable clues for diagnosing the problem. Examples include P0706, P0707, P0708 and P0709.
Frequently Asked Questions
What does the P0705 code mean? The P0705 code indicates a problem with the transmission range switch circuit, which informs the vehicle's computer about the gear selector's position. This can lead to various drivability issues.
What are the symptoms of a P0705 code? Symptoms can include a no-start condition, starting in gear, incorrect gear indication, shifting problems, and non-functional reverse lights.
Can I drive with a P0705 code? It's not recommended to drive with a P0705 code, as it can cause shifting problems and potentially damage the transmission. Furthermore, starting the car in gear is a significant safety hazard.
How do I fix a P0705 code? Fixing a P0705 code involves diagnosing the problem, which may include testing the TRS, wiring, and shift linkage, and then replacing or repairing any faulty components.
How much does it cost to fix a P0705 code? The cost to fix a P0705 code can vary, but typically ranges from $50 to $300, depending on the cause and the extent of the repair. Replacing the switch is usually the most frequent repair.
Conclusion
The P0705 diagnostic trouble code signifies an issue within the transmission range switch circuit, potentially leading to significant drivability problems. A methodical approach to diagnosis, involving visual inspection, electrical testing, and component verification, is crucial for pinpointing the root cause and implementing the appropriate repair, which often involves replacing the TRS or addressing wiring issues. Prioritizing accurate diagnosis and repair will ensure optimal transmission performance and prevent further damage.