P1704

What it means

P1704 on a Mercury is logged by the transmission control side of the powertrain control module as a general transmission system problem. The wording is broad, so the exact test that failed depends on the model, year and transmission fitted. Something in the transmission control inputs, outputs or communication did not match what the module expected, and the code was stored.

Symptoms

• Transmission warning light or malfunction indicator lamp on
• Harsh, delayed or flared gear changes
• Transmission stuck in one gear or in a limp-home mode
• Gear selector position not matching the gear shown or engaged
• Poor fuel economy or reduced performance
• Intermittent fault that clears and returns

Possible causes

• Low, degraded or contaminated transmission fluid affecting operation and pressurelikely
• Damaged, corroded or loose wiring and connectors at the transmission or control modulelikely
• Faulty transmission sensor or switch signal, depending on the transmission fittedpossible
• Faulty shift solenoid or internal valve body wear, depending on the transmission fittedpossible
• Poor battery condition or charging fault causing low voltage and false faultspossible
• Fault in the powertrain control module itself or outdated softwarerare

How to diagnose

1. Read all stored and pending codes and record the freeze frame data, noting other transmission or communication codes
2. Check the transmission fluid level and condition against the manufacturer's procedure for that model
3. Check battery condition and charging voltage, as low voltage can set transmission faults
4. Inspect the transmission wiring harness and connectors for chafing, oil contamination, corrosion and pin damage
5. Check the selector linkage or cable adjustment and that the selector position matches what the scan data shows
6. Look up the model-specific test procedure and live data for the transmission fitted, and compare commanded and actual values
7. Test the suspect sensor, switch or solenoid circuits for resistance, supply, earth and signal against specification
8. Check for applicable software updates or technical bulletins for the vehicle

How to fix

• Correct the fluid level or replace degraded fluid and filter as per the service schedule for that transmission
• Repair or replace damaged wiring and clean or replace faulty connectors
• Replace any confirmed faulty transmission sensor, switch or solenoid
• Repair the battery or charging fault if voltage is out of range
• Carry out internal transmission repair if a mechanical or hydraulic fault is confirmed
• Update the control module software only if a known fault is covered by an update, or replace the module if confirmed faulty

Can I keep driving?

This code for other makes

• P1704FordTransmission system problems
• P1704LincolnTransmission System Problems
• P1704OtherDigital TRS Failed to Transition States in KOEO / KOER
• P1704Subaru2-4 Brake Timing Solenoid Valve Circuit Malfunction
• P1704VolkswagenKick Down Switch Malfunction

Nearby codes

• P1703MercuryBrake On Off Switch Out of Self-Test Range
• P1705MercuryManual Lever Position Sensor Out of Self-Test Range