Skip to content
GTECH Calibration
Portal

P1520

Gear Indicator System.

  • Saturn
  • Powertrain
  • Manufacturer code
  • Low severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
5
AreaVehicle speed, idle control and auxiliary inputs
20
FaultThe specific fault in that area

What it means

On a Saturn, P1520 is a manufacturer-specific code for the Gear Indicator System. The control unit has detected a fault in the circuit or signal that drives the gear position display, or the gear position information does not match what the transmission or range switch is reporting. The exact trigger and which module sets it depend on the model and transmission fitted.

Symptoms

  • Gear selector display on the dash is blank, flickering or shows the wrong gear
  • Malfunction indicator lamp or transmission warning lamp on
  • Gear display does not match the selector position
  • Shifting may feel normal, or there may be harsh or erratic shifts if the range signal is faulty
  • Car may not start in Park or Neutral if the range switch is at fault

Possible causes

  • Faulty or misadjusted transmission range (park/neutral) switch giving an incorrect or erratic gear position signallikely
  • Damaged wiring, corrosion or loose connectors in the range switch or gear indicator circuitlikely
  • Faulty gear indicator display or instrument cluster driver circuitpossible
  • Selector linkage or cable out of adjustment so the switch position does not match the leverpossible
  • Low battery voltage or poor earth causing intermittent circuit faultspossible
  • Fault within the powertrain or transmission control modulerare

How to diagnose

  1. Read all stored and pending codes and note the freeze frame data, checking for other transmission or range switch codes
  2. Compare the selector lever position with the gear shown on the display in each position and note where it goes wrong
  3. Check battery condition and charging voltage, and inspect the main earths
  4. Inspect the range switch wiring and connectors for damage, water ingress, corrosion or loose pins
  5. Check the selector cable or linkage adjustment against the manufacturer's procedure for the model
  6. View the live gear position or range switch data on a scan tool and see if it follows the lever smoothly
  7. Test the range switch and indicator circuit for continuity, shorts and correct voltage using the wiring diagram for that model
  8. Check the instrument cluster and control module only after the switch and wiring have been proved good

How to fix

  • Repair or replace damaged wiring and clean or renew corroded connectors
  • Adjust the selector linkage and range switch to specification
  • Replace the faulty range switch
  • Repair or replace the gear indicator display or instrument cluster if it is proved faulty
  • Fix battery or earth faults, then clear the code and road test to confirm it does not return

Can I keep driving?

Low severity

The car can usually be driven and booked in for repair, as this is mainly a display or signal fault. If it also refuses to start, or the gearbox shifts harshly or erratically, have it checked promptly.

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

This code for other makes

Nearby codes