If your Honda’s check engine light is on and you’ve scanned for codes, seeing P1705 can be confusing. What does Honda P1705 code mean? Simply put, it indicates a problem with the transmission’s shift control system, specifically related to the Vehicle Speed Sensor (VSS) circuit.
This code is common in many Honda and Acura models and, while it won’t typically leave you stranded, it can lead to poor shifting, reduced fuel economy, and a lit dashboard. Let’s break down what this code means, why it happens, and how you can fix it.
What Does Honda P1705 Code Mean?
In technical terms, Diagnostic Trouble Code (DTC) P1705 is defined as “Transmission Range Switch Circuit Malfunction (Secondary)” for Honda vehicles. The transmission range switch is also known as the neutral safety switch or inhibitor switch. It tells the Powertrain Control Module (PCM) what gear you’ve selected—Park, Reverse, Neutral, or Drive.
The “Secondary” part of the definition is key. Your car has a primary circuit for this switch that handles the main gear signals. The secondary circuit provides a backup or additional confirmation signal. Code P1705 triggers when the PCM detects an implausible signal or a fault in this secondary circuit.
Common Symptoms of a P1705 Code
You’ll likely notice more than just a warning light. Here are the most frequent symptoms:
* Illuminated Check Engine Light (CEL): This is always the first sign.
* Harsh or Improper Shifting: The transmission may shift erratically, too early, or too late.
* Failure to Shift: You might get stuck in a single gear, often 2nd or 3rd (limp mode).
* Speedometer Issues: The speedometer may behave erratically or not work at all, as the VSS signal is involved.
* Cruise Control Inoperative: The cruise control system will often disengage because it relies on a steady speed signal.
* Difficulty Starting: In some cases, the car may not start because the PCM doesn’t know it’s in Park or Neutral.
What Causes the P1705 Code in a Honda?
Several issues can lead to this code. They range from simple electrical faults to more serious mechanical problems. Here’s a list of the usual suspects:
* Faulty Transmission Range (Neutral Safety) Switch: This is the most common culprit. The internal contacts wear out or fail.
* Damaged Wiring or Connectors: The wires leading to the switch can get frayed, corroded, or damaged by heat.
* Poor Electrical Connection: A loose or dirty connector at the switch or PCM can interrupt the signal.
* Low Transmission Fluid: Incorrect fluid level can affect hydraulic pressure and sensor operation.
* Faulty Vehicle Speed Sensor (VSS): Since the systems are linked, a bad VSS can cause this code.
* Issues with the PCM: While rare, the computer itself could malfunction (always diagnose everything else first).
How to Diagnose and Fix a P1705 Code
Before you start, you’ll need a basic tool set and a digital multimeter (DMM). A reliable scan tool to confirm the code is also very helpful. Always begin with the simplest, least expensive checks.
Safety First: Ensure the vehicle is on a level surface, the parking brake is firmly engaged, and the engine is off and cool before starting.
Step 1: Preliminary Checks
Start with these visual and simple inspections.
1. Check the Transmission Fluid: Locate the dipstick, wipe it clean, reinsert it, and pull it out to check the level and condition. The fluid should be at the proper level and a clear reddish color. Dark, burnt-smelling fluid indicates internal problems.
2. Perform a Visual Inspection: Look at the wiring harness and connectors going to the transmission range switch (usually on the side of the transmission). Check for any obvious damage, chafing, or corrosion.
3. Clear the Code and Test Drive: Use your scan tool to clear the DTC. Take the car for a short drive. If the code returns immediately, you have a hard fault. If it takes a while to return, the issue might be intermittent.
Step 2: Testing the Transmission Range Switch
The switch is the prime suspect. Here’s how to test it.
1. Locate the Switch: Consult your vehicle’s service manual. It’s typically mounted on the transmission case, connected to the shift lever shaft.
2. Access the Electrical Connector: Disconnect the electrical plug from the switch.
3. Test for Continuity: Set your multimeter to the Ohms (Ω) setting. Using the wiring diagram for your specific model, test the continuity between the switch terminals in each gear position (P, R, N, D, etc.). The continuity should change as you move the shift lever. No change indicates a faulty switch.
Step 3: Checking Wiring and Connections
If the switch tests good, the wiring is next.
1. Check for Power and Ground: Reconnect the switch. With the ignition key in the “ON” position, back-probe the connector pins with your multimeter (set to Volts DC). Check for reference voltage (usually 5V or 12V) and a good ground according to the wiring diagram.
2. Check for Shorts or Opens: With the battery disconnected, use your multimeter’s continuity setting to check the wires from the switch connector back to the PCM connector for breaks (open circuit) or shorts to power or ground.
Step 4: Replacing the Transmission Range Switch
If you’ve determined the switch is bad, replacement is the next step. The process is generally straightforward.
1. Disconnect the Battery: Always disconnect the negative terminal first for safety.
2. Unplug the Electrical Connector.
3. Remove the Switch: It’s usually held by one or two bolts. Carefully remove them.
4. Install the New Switch: Before threading it in fully, you may need to align it. Sometimes the new switch comes preset. Consult a manual for alignment procedures—misalignment will cause shifting and starting problems.
5. Reconnect Everything: Bolt in the switch, reconnect the plug, and reconnect the battery.
6. Clear Codes and Relearn Procedure: Start the car, clear the codes with your scanner, and cycle the shifter through all positions. A test drive will confirm the fix.
Cost to Fix a P1705 Code
The cost varies widely depending on the cause and whether you use a professional mechanic.
* Transmission Range Switch Part Cost: Typically between $50 and $150 for the part.
* Professional Labor Cost: Expect 1-2 hours of labor. Total repair cost at a shop usually ranges from $200 to $400.
* DIY Cost: If you do it yourself, you’ll only pay for the part and any tools you don’t already own, making it a very affordable repair.
Can You Drive with a P1705 Code?
Technically, you can often drive the car, but it’s not recommended. The vehicle will likely be in a fail-safe or “limp” mode to protect the transmission. This means reduced power, poor fuel economy, and you risk causing further damage if the root cause is low fluid or a serious electrical short. Have the problem diagnosed as soon as you can.
FAQ Section
Q: Is Honda P1705 a serious code?
A: It’s moderately serious. It won’t usually cause a breakdown, but it leads to poor performance and can be a sign of other issues. It should be addressed promptly.
Q: Can a bad battery cause a P1705 code?
A: It’s uncommon but possible. A weak battery or alternator can cause low system voltage, leading to erratic sensor signals that the PCM might interpret as a fault.
Q: What’s the difference between P1705 and P0705?
A: P0705 is a more generic “Transmission Range Sensor Circuit Malfunction” code. P1705 is Honda’s specific designation for the secondary circuit of that same system. The diagnosis is very similar.
Q: Will disconnecting the battery reset the P1705 code?
A: Yes, disconnecting the battery will clear the code and turn off the light temporarily. However, if the underlying problem isn’t fixed, the code will return within a few drive cycles.
Q: Could this code be related to my Honda’s TCM?
A: Yes, the Transmission Control Module (TCM) or the integrated PCM uses the signal from the range switch. A fault in the TCM itself could theoretically cause this code, but it’s much less likely than a switch or wiring issue.
Dealing with a P1705 code in your Honda can be frustrating, but it’s often a repairable issue. By starting with simple checks like the fluid level and wiring, you can often find the problem without a huge expense. Remember, the transmission range switch is the most frequent cause, and replacing it is a common DIY job for many home mechanics. If you’re ever unsure, consulting a professional technician is always a wise choice to ensure your Honda returns to its reliable, smooth-shifting self.