Open circuit or poor connection in the stator temperature switch wiring or connector; Wiring chafed, corroded or shorted to a voltage supply; Faulty stator temperature switch, or one stuck in the open state; Corroded or contaminated internal harness or case connector, possibly with fluid ingress; Transmission control module fault or damaged reference supply; Genuine overheating of the transmission fluid or torque converter causing the switch to change state.

P1874

TCC Stator Temp Switch Circuit High.

GMC
Powertrain
Manufacturer code
Medium severity

How this code is built

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

What it means

P1874 on a GMC means the transmission control module has detected a high voltage signal on the torque converter clutch (TCC) stator temperature switch circuit. The switch is meant to tell the module when the torque converter is running hot, so a circuit that reads high means the signal is out of the expected range or stuck in one state. The exact switch location, wiring and strategy depend on the model, engine and transmission fitted.

Symptoms

Malfunction indicator lamp or transmission warning lamp on
Torque converter clutch not locking up, or locking up at odd times
Slightly worse fuel economy on steady cruising
Higher than normal transmission temperature on long or towing journeys
Occasional harsh or delayed shifts on some models

Possible causes

Open circuit or poor connection in the stator temperature switch wiring or connectorlikely
Wiring chafed, corroded or shorted to a voltage supplylikely
Faulty stator temperature switch, or one stuck in the open statepossible
Corroded or contaminated internal harness or case connector, possibly with fluid ingresspossible
Transmission control module fault or damaged reference supplyrare
Genuine overheating of the transmission fluid or torque converter causing the switch to change staterare

How to diagnose

Read all stored codes and freeze frame data, noting transmission temperature, speed and load when the code set, then check for any related codes.
Check the transmission fluid level, condition and smell, and look for signs of overheating such as dark or burnt fluid.
Inspect the external transmission harness and connector for damage, corrosion, heat damage, fluid contamination and bent or pushed-back pins.
Using the wiring diagram for the exact model and transmission, check the switch circuit for open circuit, short to voltage and short to earth, and check the earth and supply.
Monitor the switch state and transmission temperature in live data while the transmission warms up, and see whether the switch changes state as expected.
Test the switch itself against the manufacturer's specification, if it is accessible, and compare with the circuit readings.
Check the transmission cooler flow and lines if overheating is suspected.
If the wiring and switch test correctly, check the control module connectors and follow the manufacturer's procedure before considering module faults.

How to fix

Repair or replace damaged wiring, and clean or replace corroded or damaged connectors and terminals.
Replace the stator temperature switch or the internal harness section if testing shows it is faulty, following the procedure for that transmission.
Correct any fluid level or condition problem and rectify the cause of any overheating, such as a restricted cooler.
Repair any fluid leak into the connector and replace contaminated components.
Replace or repair the transmission control module only after wiring and switch faults are ruled out, and carry out any programming the manufacturer requires.

Can I keep driving?

Medium severity

The vehicle can usually be driven for a short time, but get it checked soon because the converter clutch may not lock up and overheating may go unnoticed. Avoid towing or heavy loads, and stop if the transmission runs hot or shifts badly.

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