P1705 Code: That Flashing 'D' Light Means Range Sensor Trouble

What Does P1705 Actually Mean?

Every automatic transmission has a Transmission Range Sensor (TRS) — also called the neutral safety switch, PRNDL switch, or gear position sensor depending on the manufacturer. Its job is simple but critical: tell the Transmission Control Module (TCM) which gear position the driver has selected with the shifter. The TCM uses this signal to decide which gear to actually engage, when to allow engine starting (only in P or N), and when to activate reverse lights and other PRNDL display indicators.

P1705 fires when the TCM receives a TRS signal that doesn't make physical sense — like signals for two gears simultaneously, or a signal value that falls between the defined voltage ranges for any valid gear position. Translation: the TCM has no idea what gear you want, so it activates limp mode and locks into a safe default gear. The code itself is the same family across all manufacturers, but the underlying cause varies significantly by brand.

What Are the Symptoms of P1705?

P1705 symptoms are obvious and immediate — unlike sensor codes that can hide for weeks, this one announces itself the moment you start the vehicle:

Is P1705 Code Serious?

High severity — drive only as far as necessary to reach repair. P1705 itself is an electrical fault code, but the limp mode it triggers can cause real damage if you keep driving:

Good news: P1705 itself is one of the cheapest serious-looking codes to fix when diagnosed correctly. The bad news: ignoring it for weeks of daily driving can turn a $200 sensor swap into a $3,000 transmission rebuild from accumulated thermal damage.

What Causes a P1705 Code? (Ranked by Frequency)

Cause distribution varies dramatically by manufacturer. Honda P1705 is dominated by aftermarket remote starter issues; GM is dominated by TRS alignment problems; Nissan has a completely different meaning. Diagnose accordingly.

What You'll Need

How Do You Fix a P1705 Code?

Follow these steps in order. Step 2 — live TRS voltage testing — is the entire diagnosis. If you have a Honda, Step 3 is the second-most-likely fix.

• 1

  Scan All Codes and Note Specific Symptoms

  Plug in your scanner and record every stored code. P1705 frequently appears with companion codes:

  • P0700 (transmission control system MIL request) — almost always present with P1705
  • P0705 / P0706 (TRS circuit malfunction or range/performance) — generic equivalents
  • P0815 / P0816 (upshift/downshift switch) — related shift logic codes
  • P0753 / P0758 (shift solenoid A/B electrical) — if a solenoid is also failing

  Note your specific symptoms — these guide the diagnosis:

  • Flashing 'D' light on Honda/Acura → aftermarket remote starter is the #1 suspect
  • Code appeared after transmission service → TRS alignment is the #1 suspect
  • Slipping or harsh shifting before P1705 appeared → shift solenoid may be involved
  • Vehicle won't start in Park → TRS may be reporting wrong gear position
  • Code appeared after coastal driving / winter salt → wiring corrosion is the #1 suspect
• 2

  Read Live TRS Voltage While Moving Shifter — The Killer Diagnostic

  This is the single most decisive test for P1705. It costs nothing, takes 5 minutes, and tells you exactly where the problem is.

  • Connect scanner with engine running and parking brake engaged
  • Navigate to live data view and find "Transmission Range Sensor Voltage" or "TR Sensor" PID
  • Slowly move shifter through all positions: P → R → N → D (and D1, D2, D3 if equipped)
  • Record voltage at each position — wait 2-3 seconds at each for stable reading

  What healthy readings look like (exact values vary by manufacturer):

  • Honda Civic / Accord: P=0.5V, R=1.0V, N=1.5V, D=2.0V, D2=2.5V, D1=3.0V
  • Nissan Rogue / Altima: P=0.5V, R=4.5V, N=2.0V, D=4.0V (note: very different from Honda)
  • GM Silverado / Sierra: P=0.5V, R=1.0V, N=1.5V, D=3.0V, L=4.5V
  • Each position must be DISTINCT with at least 0.3V separation

  Three diagnostic outcomes:

  • Voltage doesn't change as shifter moves → sensor failed, disconnected, or wiring open. Go to Steps 3-5.
  • Voltage values overlap (D reads same as N, etc.) → sensor misaligned. Go to Step 4.
  • Voltage jumps erratically or shows impossible values → wiring problem or aftermarket interference. Go to Step 3 (Honda) or Step 5.

  This single test eliminates 90% of P1705 misdiagnosis. Most shops skip it and start replacing parts. Don't pay $1,500 for a "transmission rebuild" until your shop shows you these voltage readings.
• 3

  Inspect for Aftermarket Remote Starter Wiring (Honda Critical Step)

  If you have a Honda or Acura with P1705 AND a flashing 'D' indicator AND any aftermarket remote starter, this is your #1 suspect. The fix is often free:

  • Identify if a remote starter is present — small black module bolted under the dash, key fob with separate brand buttons (Compustar, Viper, AutoStart, Avital)
  • Crawl under the dash near the steering column with a flashlight
  • Look for: non-factory wire splices (often wrapped in colored tape — blue, red, yellow), T-tap connectors clipped onto factory wiring, aftermarket modules with brand labels, wires that don't match Honda's factory wire color codes
  • Common bad splices: tapped into shifter position signal wires (often green/black or yellow/black on Honda), tapped into ignition switch wiring near shifter detection circuit

  Three fix options:

  • Disconnect remote starter temporarily — if P1705 clears within 1-2 drive cycles, the starter is confirmed culprit
  • Have the starter professionally removed — $50-$120 at a shop that does mobile electronics
  • Have a clean reinstallation done — by a shop that uses factory-standard wiring practices (no T-taps, soldered splices only)

  Honda P1705 from remote starter wiring is so common that some Honda dealers won't honor warranty repairs on transmissions unless aftermarket starters are removed first. If your dealer is denying warranty, this is why.
• 4

  Verify TRS Sensor Physical Alignment

  If Step 2 showed overlapping voltage values, the sensor is misaligned — extremely common after transmission service:

  • Locate the TRS on your specific vehicle: external mount on older trucks and SUVs (bolted to transmission case at manual lever shaft); internal mount on most modern automatics (inside valve body or TCM housing)
  • For external sensors only: place shifter firmly in Neutral position
  • Look for the alignment mark — most TRS housings have a small index hole or arrow that should align with a corresponding mark on the transmission case in Neutral
  • Loosen mounting bolts slightly (do not fully remove — sensor needs to stay engaged with linkage)
  • Rotate sensor until alignment marks match exactly with shifter in Neutral
  • Tighten bolts to spec (typically 8-12 ft-lb)
  • Re-scan codes and re-test Step 2 live data to verify each gear now produces distinct voltage

  Internal-mount sensors require valve body or transmission pan removal — generally a shop job. Verify with Step 2 voltage data before authorizing this work.

• 5

  Inspect Wiring Harness and Connector

  Raise the vehicle safely on jack stands and access the TRS connector area:

  • Unplug the connector and inspect: green corrosion on pins (very common on coastal/winter-driven vehicles), oil contamination (leaking transmission pan gasket), bent or pushed-back pins, melted plastic from heat damage near exhaust
  • Pull each wire at the back of the connector — if any wire moves more than 1mm, internal crimp failed
  • Continuity test: with battery disconnected, measure resistance from each TRS connector pin back to corresponding TCM connector pin (refer to wiring diagram for color codes); should be under 5Ω
  • Short test: measure resistance from each pin to chassis ground; should be infinite (any low reading = wire shorted)
  • Harness routing inspection: trace harness for chafing on chassis points, melting near exhaust, rodent damage

  Repair damaged wires with soldered splice and heat-shrink tubing — NEVER just twist-and-tape. Apply dielectric grease to connector contacts before reinstalling.

• 6

  Replace the Transmission Range Sensor — Final Step

  Only after Steps 1-5 come back clean should you replace the sensor itself:

  • External-mount sensors are usually accessible from below the vehicle: disconnect battery, raise vehicle on jack stands, unplug harness, note position of shifter linkage before disconnecting, unbolt sensor
  • Install OEM only. Aftermarket TRS sensors for Honda, GM, Ford, and Nissan have very high failure-from-new rates — failure within weeks is common
  • Reattach shifter linkage at the same position before disconnecting
  • Verify alignment — same procedure as Step 4 with shifter in Neutral
  • Torque bolts to spec (typically 8-12 ft-lb on most platforms)
  • Apply dielectric grease to connector before plugging in
  • Internal-mount sensors require valve body or transmission pan removal — usually a shop job, $300-$700 in shop labor depending on platform
  • Clear codes and drive through all gears in safe area to allow TCM to relearn

  After installation, P1705 typically clears within 2-3 drive cycles. If it returns within a week, you missed an upstream cause — usually wiring or aftermarket interference. Go back to Steps 2-5.

How Much Does P1705 Cost to Fix?

P1705 fix costs vary dramatically by root cause. The diagnostic step (Step 2) is the single biggest cost-saver on this code — it can mean the difference between a $0 alignment fix and a $1,500 unnecessary "transmission rebuild" misdiagnosis.

Per the EPA's emissions standards ↗ EPA Vehicle Emissions I/M Program, a vehicle with an active P1705 code will fail OBD-II emissions inspection because the transmission monitor cannot complete its readiness check. The federal emissions warranty (8 years / 80,000 miles) may cover some powertrain components on certain vehicles. Always check warranty status with your dealer before paying out of pocket.

Which Vehicles Are Most Prone to P1705?

P1705 appears across many manufacturers but two platforms generate disproportionate volume: Honda/Acura (aftermarket remote starter issues) and GM Silverado / Sierra (TRS alignment after service). Deep-dives below.

P1705 on Honda Civic, Accord, CR-V, and Acura TL/MDX

Honda/Acura is the highest-volume P1705 generator in North America — and the cause pattern is remarkably consistent. The diagnosis path saves Honda owners thousands of dollars in unnecessary transmission work:

1. The aftermarket remote starter epidemic. Honda transmission electronics are particularly sensitive to electrical noise on shifter signal lines. When an aftermarket remote starter (Compustar, Viper, AutoStart, Avital) is installed, the installer often taps shifter wiring under the dash for Park/Neutral detection. Improperly done splices (T-taps, twist-and-tape, wrong wire targeted) inject noise that the TCM reads as garbled gear data. Result: flashing 'D' light, limp mode, P1705. The fix is removing the starter or having it professionally redone — often $0 to $200 total, NOT a transmission rebuild.

2. The "after a battery swap" pattern. Honda P1705 sometimes appears after a battery jump-start, battery replacement, or alternator failure. The voltage transient can briefly disrupt shifter signal lines, latching a P1705 code that requires manual clearing. If the code appears immediately after electrical work, clear it once and drive through all gears — it should not return if no underlying problem exists.

3. Honda warranty considerations. Honda's powertrain warranty (5 years / 60,000 miles federal; sometimes longer on certified pre-owned) MAY cover transmission electronics, but warranty is typically VOID if the dealer determines aftermarket electrical accessories caused the failure. This is why some dealers refuse warranty repair when remote starters are present. If your Honda is under warranty AND has a remote starter, have it professionally removed before bringing the vehicle in for diagnosis.

P1705 on Chevrolet Silverado, GMC Sierra, and GM SUVs

GM platforms generate a different P1705 cause pattern — driven by post-service TRS alignment issues and transmission fluid issues:

1. The post-transmission-service alignment pattern. Silverado 1500, Sierra 1500, Tahoe, Suburban, Yukon, Escalade with the 6L80, 6L90, or 8L90 transmissions have an external TRS that's commonly disturbed during transmission pan service, valve body work, or transmission removal. If the shop reinstalls without proper alignment, P1705 appears within a few drive cycles after service. Fix: 15-minute alignment adjustment, $0 in parts. Most overlooked GM P1705 cause.

2. The low transmission fluid trigger. GM Chevy Malibu (especially 6-speed automatic), Equinox, and some Buick LaCrosse models can trigger P1705 when transmission fluid is severely low. Reduced hydraulic pressure affects internal-mount range sensor signal integrity. Check fluid level with engine running at proper temperature per service manual; top up with correct OE-spec fluid (DEXRON-VI on most modern GM trans). Some Chevy Malibu owners report P1705 paired with P0741 (TCC stuck off) due to fluid issues.

3. The TSB and warranty landscape. GM has issued service bulletins on transmission electrical issues across multiple model years. Some 2015-2019 Silverado/Sierra 8L90 transmissions had software updates that addressed shift-quality issues including P1705 in some configurations. Check with your GM dealer using your VIN before paying for parts — software-only fixes are sometimes covered under emissions warranty.

Should You DIY or Call a Mechanic?

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Frequently Asked Questions