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DTC codes / Volkswagen codes / P1585

P1585 · VolkswagenTransmission Mount Valves Open Circuit

P1585 on Volkswagen vehicles indicates that the transmission control module (TCM) has detected an open circuit in the wiring for the transmission mount valves, which are solenoid valves used to control the hydraulic mount's stiffness. The TCM monitors the circuit and sets this code when the expected current or voltage is outside the normal range, typically because the circuit is broken or disconnected.

SystemPowertrain
Code typeVolkswagen specific
SeverityLow
Fix difficultyIntermediate
AreaVehicle speed, idle control and auxiliary inputs

Symptoms you may notice

  • Illumination of the malfunction indicator lamp (MIL) on the dashboard.
  • Often no symptoms besides the warning light, as the fault may not affect drivability.
  • Possible slight increase in vibration or harshness during gear changes if the mount fails to adjust.
  • In some cases, a stored code may be accompanied by a transmission-related message in the instrument cluster.
  • No noticeable performance loss in most instances, but the vehicle may fail an emissions inspection due to the MIL.
  • Rarely, a default limp-home mode may be triggered if the TCM interprets the fault as critical, but this is uncommon.

Common causes, most likely first

  1. Broken or chafed wire in the harness between the TCM and the transmission mount valve.
  2. Corroded or disconnected electrical connector at the transmission mount valve.
  3. Failed transmission mount valve solenoid (open coil).
  4. Damaged pins or terminals in the TCM connector.
  5. Internal fault in the TCM driver circuit for the mount valve.
  6. Rodent damage to the wiring harness.
  7. Aftermarket or improper wiring repair that introduced an open circuit.

How to diagnose and fix it

  1. Verify the code with a Volkswagen-specific scan tool and check for any related codes in the transmission control module.
  2. Visually inspect the wiring harness and connector at the transmission mount valve for damage, corrosion, or loose pins.
  3. Measure the resistance of the transmission mount valve solenoid with a multimeter and compare to the manufacturer's specification.
  4. Check for continuity and short-to-ground in the wiring between the TCM and the valve, repairing any breaks or shorts.
  5. If the solenoid resistance is out of spec, replace the transmission mount valve assembly.
  6. If wiring and solenoid are good, test the TCM output signal with an oscilloscope or substitute a known-good TCM to rule out internal failure.
  7. Clear the code and perform a road test to confirm the repair and ensure the code does not return.

Transmission Mount Valve Circuit Nuances

  • A common oversight is assuming the transmission mount valve itself is faulty when the real issue is a corroded connector or a broken wire hidden inside the loom.
  • The transmission mount valve often fails intermittently, so a resistance check at room temperature may pass; wiggle-test the harness while monitoring resistance to catch intermittent opens.
  • This code can be set by a low battery or charging system issue that causes the TCM to log a false open circuit, so always check battery voltage and ground connections first.
  • On some Volkswagen models, the transmission mount valve shares a ground with other components; a bad ground can trigger P1585 along with other unrelated codes.
  • Replacing the transmission mount valve without checking the TCM software for updates can lead to a repeat failure if the TCM driver is faulty or the calibration is incorrect.

Can I keep driving with P1585?

The vehicle is generally safe to drive with P1585 because the fault typically does not affect transmission operation or safety, but you should avoid heavy acceleration or towing until the circuit is repaired to prevent potential mount wear. Have the code diagnosed soon to prevent secondary damage and to ensure the vehicle passes emissions testing.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for Volkswagen vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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