Skip to content
GTECH Calibration
Portal

P1780

Park Neutral Position Switch Circuit Engine Torque Signal Circuit.

  • Oldsmobile
  • Powertrain
  • Manufacturer code
  • Medium severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
7
AreaTransmission
80
FaultThe specific fault in that area

What it means

On Oldsmobile (GM) vehicles, P1780 relates to the Park/Neutral Position (PNP) switch circuit and the engine torque signal circuit. The powertrain control module saw a PNP switch signal that did not agree with other inputs, or a torque signal between the engine and transmission control that was missing or implausible. The exact test conditions and wiring layout depend on the model, engine and transmission.

Symptoms

  • Malfunction indicator lamp on
  • Engine will not start in Park or Neutral, or starts in gear
  • Harsh, delayed or flared gear changes
  • Erratic or incorrect gear position display
  • Rough or unstable idle when selecting Drive or Reverse
  • Reversing lamps not working correctly

Possible causes

  • Park/Neutral position switch out of adjustment or worn internallylikely
  • Damaged, corroded or loose wiring or connector at the PNP switchlikely
  • Shift linkage or cable out of adjustment so the switch does not match the selector positionlikely
  • Open or short circuit in the engine torque signal wire between the engine and transmission controlpossible
  • Poor power or earth supply to the control modulepossible
  • Faulty powertrain control module or transmission control modulerare

How to diagnose

  1. Read the stored codes and freeze frame data, and note any other transmission or engine codes present
  2. Check the selector position shown on the scan tool against the actual lever position in each gear
  3. Inspect the PNP switch connector and wiring for damage, corrosion, water ingress and chafing
  4. Check the shift linkage or cable adjustment and the switch alignment against the model's workshop data
  5. Test the PNP switch signals for each selector position and compare them with the manufacturer's specification
  6. Check the engine torque signal circuit for continuity, shorts and correct voltage using the wiring diagram for the specific model
  7. Check the module power and earth supplies and battery condition
  8. Clear the code and road test, watching whether it returns and under what conditions

How to fix

  • Adjust or replace the PNP switch and set it correctly to the specification
  • Repair or replace damaged wiring and clean or replace faulty connectors
  • Adjust or repair the shift linkage or cable
  • Repair the open or short in the torque signal circuit
  • Correct poor power or earth connections to the control module
  • Replace and programme a control module only after the wiring and inputs are proven good

Can I keep driving?

Medium severity

The car can usually be driven for a short time, but gear changes and starting may be affected, so have it checked soon. Stop driving if it starts in gear, will not hold a gear or shifts harshly.

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

This code for other makes

Nearby codes