Skip to content
GTECH Calibration
Portal

P1790

Transmission Range Display Circuit Open.

  • Volkswagen
  • Powertrain
  • Manufacturer code
  • Medium severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
7
AreaTransmission
90
FaultThe specific fault in that area

What it means

On Volkswagen, P1790 means the transmission control unit has detected an open circuit in the transmission range display (the gear selector position indicator in the instrument cluster or selector area). The control unit expects a valid signal or load on this circuit and has found none, so the fault is stored. The exact wiring and which component drives the display varies by model and gearbox type.

Symptoms

  • Gear selector position display blank, flickering or showing the wrong gear
  • Warning lamp or message for the gearbox on the dashboard
  • Gearbox may go into a limp or fixed gear on some models
  • Selector lever illumination or position indicator not working
  • Intermittent fault that comes and goes with vibration or temperature

Possible causes

  • Damaged, corroded or loose connector at the selector lever or display unitlikely
  • Open circuit or chafed wiring between the transmission control unit and the range displaylikely
  • Faulty selector lever module or range display/indicator circuitpossible
  • Fault in the instrument cluster affecting the display circuitpossible
  • Poor earth or power supply to the selector or display circuitpossible
  • Fault inside the transmission control unitrare

How to diagnose

  1. Read all fault codes and freeze frame data, noting whether other gearbox, selector or cluster codes are stored
  2. Clear the code and see whether it returns straight away or only intermittently
  3. Visually inspect the selector lever connector, cluster connector and visible wiring for damage, corrosion, moisture or pin tension problems
  4. Wiggle-test the harness with the ignition on while watching live data and the display for changes
  5. Check the relevant wiring diagram for your model and gearbox, then test continuity of the display circuit and its power and earth feeds
  6. Check the live data for the selector position and compare it to the actual lever position
  7. Test the selector lever module and display function using the manufacturer's guided diagnostics
  8. Check for any applicable software updates or technical bulletins for the model if no physical fault is found

How to fix

  • Clean, repair or replace faulty connectors and terminals
  • Repair or replace open-circuit or damaged wiring sections
  • Replace the faulty selector lever module or display component
  • Repair the power or earth supply fault to the circuit
  • Repair or replace the instrument cluster if it is confirmed as faulty
  • Replace or reprogram the transmission control unit only after all other causes are ruled out and the fault is confirmed

Can I keep driving?

Medium severity

The car can usually be driven short-term if the gearbox still shifts normally, but get it checked soon. If the gearbox is in limp mode, shifting harshly or you cannot tell which gear is selected, limit driving until it is fixed.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.

This code for other makes

Nearby codes