Open circuit or poor connection in the stator temperature switch wiring or connector (corrosion, bent or pushed-back pins); Faulty stator temperature switch (internal open or stuck state); Wiring short to voltage on the switch signal circuit; Genuine transmission overheating (low or degraded fluid, cooler restriction, towing or heavy load) causing the switch to change state; Damaged internal transmission harness or pass-through connector; Faulty transmission control module or its internal circuit.

P1874

TCC Stator Temp Switch Circuit High.

Oldsmobile
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 an Oldsmobile means the transmission control module has seen a high voltage condition in the torque converter clutch (TCC) stator temperature switch circuit. The switch is used to monitor converter or fluid temperature so the TCC apply strategy can be protected, and the module saw a signal that is higher than expected for the circuit's state. The fault is usually electrical (wiring, connector or switch), though it can also be set by genuine overheating, and the exact switch location and operation depend on the model and transmission.

Symptoms

Check engine or service transmission light on
TCC not applying, or applying only intermittently
Poorer fuel economy at cruising speed
Higher than normal transmission temperature or a hot smell
Torque converter shudder or unusual engine rpm at steady speed
Transmission may go into a default or limited operating strategy

Possible causes

Open circuit or poor connection in the stator temperature switch wiring or connector (corrosion, bent or pushed-back pins)likely
Faulty stator temperature switch (internal open or stuck state)likely
Wiring short to voltage on the switch signal circuitpossible
Genuine transmission overheating (low or degraded fluid, cooler restriction, towing or heavy load) causing the switch to change statepossible
Damaged internal transmission harness or pass-through connectorpossible
Faulty transmission control module or its internal circuitrare

How to diagnose

Read all stored and pending codes and note the freeze frame data, looking for other TCC, temperature or voltage-related faults
Check transmission fluid level, condition and smell, and ask about towing, heavy loads or recent overheating
Inspect the switch connector and harness for corrosion, water ingress, damaged pins, chafing and signs of heat
Check the transmission cooler lines and cooler flow for restriction, following the procedure for the specific model
With the transmission at a known temperature, view the switch state in live data and compare it with what you expect for that temperature
Test the signal circuit for short to voltage or open circuit using the wiring diagram for the model, and check the ground and reference feeds
Check the switch itself against the manufacturer's specification, which varies by transmission
Check for a TCM software update only if one is documented for this fault on the vehicle

How to fix

Repair or replace damaged wiring and clean or replace corroded or damaged connectors
Replace the stator temperature switch if it fails testing
Repair any short to voltage in the signal circuit
Correct the overheating cause: restore the fluid level or change degraded fluid, and clear any cooler restriction
Repair or replace the internal transmission harness or connector if it is faulty
Replace or reprogram the TCM only after wiring and switch faults are ruled out and a fault is confirmed

Can I keep driving?

Medium severity

The car can usually be driven short distances, but the TCC may be disabled and the transmission may run hotter. Avoid towing and heavy loads, and have it checked soon, especially if the transmission feels hot or slips.

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