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P1874

TCC Stator Temp Switch Circuit High.

  • Saturn
  • 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

On a Saturn, P1874 means the transmission control module has seen a high voltage on the torque converter clutch (TCC) stator temperature switch circuit. The switch is meant to tell the control unit when the converter stator or fluid is running hot, so the TCC strategy can be adjusted. A high signal that does not match the conditions, or that stays high, sets the code. Details of the circuit and the switch location depend on the model and transmission.

Symptoms

  • Check engine or service transmission warning light on
  • Torque converter clutch not engaging, or engaging only intermittently
  • Slightly worse fuel economy on steady cruising
  • Higher engine revs at motorway speed because the TCC is locked out
  • Transmission running hotter than normal in some cases

Possible causes

  • Open circuit or poor connection in the stator temperature switch wiring or connectorlikely
  • Faulty stator temperature switch stuck open or reading incorrectlylikely
  • Short to voltage on the signal wirepossible
  • Corroded or damaged transmission internal harness or case connectorpossible
  • Genuine overheating of the transmission fluid from low level, degraded fluid or a slipping converterpossible
  • Fault inside the transmission control modulerare

How to diagnose

  1. Read all stored and pending codes and the freeze frame data, and note whether other transmission codes are present
  2. Check the transmission fluid level and condition, and look for signs of overheating such as a burnt smell or dark fluid
  3. Inspect the wiring and connectors to the switch and the transmission case connector for damage, corrosion, water ingress or pushed-out pins
  4. Using the manufacturer's wiring diagram for the model, check the signal circuit for continuity, short to voltage and short to earth
  5. Check the reference voltage and earth at the switch connector with the ignition on
  6. Test the switch itself against the manufacturer's specification, noting it may need to be tested at a known temperature
  7. Watch live data for the switch state while the transmission warms up and compare it with the expected behaviour for your model
  8. Clear the code and road test to see if it returns before replacing parts

How to fix

  • Repair or replace damaged wiring and clean or replace corroded connectors
  • Replace the stator temperature switch if it fails testing, following the procedure for your transmission
  • Repair any short to voltage on the signal circuit
  • Replace the internal harness or case connector if it is damaged
  • Correct the fluid level or change degraded fluid, and investigate the cause of any overheating
  • Replace or reprogram the control module only after the wiring and switch are proven good and a fault is confirmed

Can I keep driving?

Medium severity

The car can usually be driven for a short time, but with the TCC possibly locked out it may use more fuel and run the transmission hotter. Get it checked soon, and avoid heavy loads or towing until it is repaired.

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

This code for other makes

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