Faulty performance selector switch (worn or dirty contacts, internal failure); Damaged, chafed or corroded wiring to the switch (open circuit, short to earth or short to voltage); Loose, corroded or water-affected connector at the switch or transmission control module; Poor earth or low supply voltage to the switch circuit; Fault in the transmission control module or the module that reads the switch; Aftermarket accessory wiring interfering with the switch circuit.

P1801

Performance Selector Switch Failure.

GMC
Powertrain
Manufacturer code
Low severity

How this code is built

P: SystemPowertrain
1: Defined byThe manufacturer
8: AreaTransmission
01: FaultThe specific fault in that area

What it means

P1801 on a GMC means the transmission control module has detected a fault in the performance selector switch circuit. This is the driver-operated switch that chooses between transmission shift modes such as normal and performance (or economy/power). The module set the code because the signal from the switch was missing, out of range or implausible for the position it expected. Which switch, wiring and connector are involved depends on the model and transmission, so check the manufacturer wiring information for the vehicle.

Symptoms

Transmission warning or check engine light on
Shift mode selector has no effect on shift behaviour
Transmission stuck in one shift pattern, normal or performance
Harsh, late or early shifts compared with normal
Intermittent loss of the selected mode after starting

Possible causes

Faulty performance selector switch (worn or dirty contacts, internal failure)likely
Damaged, chafed or corroded wiring to the switch (open circuit, short to earth or short to voltage)likely
Loose, corroded or water-affected connector at the switch or transmission control modulepossible
Poor earth or low supply voltage to the switch circuitpossible
Fault in the transmission control module or the module that reads the switchrare
Aftermarket accessory wiring interfering with the switch circuitrare

How to diagnose

Read all stored and pending codes and note any other transmission, battery or network codes
Review freeze frame data and check whether the fault is constant or intermittent
Operate the selector switch through all positions and see if the scan data for the switch state changes accordingly
Visually inspect the switch, its wiring and connectors for damage, moisture, corrosion and bent or pushed-back pins
Check battery condition and charging voltage, then check supply and earth at the switch against the wiring diagram
Test the switch circuit for continuity, short to earth and short to voltage with the connectors disconnected
Test the switch itself for correct resistance or continuity in each position as per manufacturer specification
Check for software updates or technical bulletins for the specific model and transmission before considering the control module

How to fix

Replace the performance selector switch if it fails the position or resistance test
Repair or replace damaged wiring and secure it clear of heat and chafing points
Clean, repair or replace corroded or loose connectors and terminals
Restore a good earth or supply to the switch circuit
Replace or reprogram the control module only after the wiring and switch are proven good, and an updated calibration is available
Clear the code and road test to confirm it does not return

Can I keep driving?

Low severity

The vehicle can normally be driven, though shift mode selection may not work and shifts may feel different. Book it in soon, and stop if the transmission shifts harshly, slips or goes into limp mode.

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