Open or damaged wiring in the TCC stator temperature switch circuit, such as a broken wire or corroded connector terminal; Failed TCC stator temperature switch itself, reading high resistance or open; Poor connection at the transmission pass-through connector or the TCM harness; Chafed or pinched harness near the transmission case or exhaust components; Internal transmission harness damage or fluid contamination affecting the switch signal; Less commonly, a faulty TCM that misinterprets a normal signal

DTC codes / GM codes / P1874

P1874 · GMTCC Stator Temp Switch Circuit High

Q: What does code P1874 mean?

TCC Stator Temp Switch Circuit High. P1874 on GM vehicles means the transmission control module (TCM) has detected an abnormally high voltage on the torque converter clutch (TCC) stator temperature switch circuit, which usually indicates an open circuit or a sensor that has failed to a high-resistance state. The TCM uses this switch to monitor stator temperature and adjust TCC apply strategy, so a high signal forces it into a default or protective mode.

P1874 on GM vehicles means the transmission control module (TCM) has detected an abnormally high voltage on the torque converter clutch (TCC) stator temperature switch circuit, which usually indicates an open circuit or a sensor that has failed to a high-resistance state. The TCM uses this switch to monitor stator temperature and adjust TCC apply strategy, so a high signal forces it into a default or protective mode.

SystemPowertrain

Code typeGM specific

SeverityMedium

Fix difficultyIntermediate

AreaTransmission

Symptoms you may notice

Illumination of the check engine light or service transmission message, often with no other noticeable symptoms
Harsh or delayed torque converter clutch engagement, especially when the transmission is cold
Poor fuel economy because the TCC may not lock up as designed
Slightly elevated transmission fluid temperature during sustained highway driving
In some cases, the transmission may stay in a default gear or inhibit lockup entirely

Common causes, most likely first

Open or damaged wiring in the TCC stator temperature switch circuit, such as a broken wire or corroded connector terminal
Failed TCC stator temperature switch itself, reading high resistance or open
Poor connection at the transmission pass-through connector or the TCM harness
Chafed or pinched harness near the transmission case or exhaust components
Internal transmission harness damage or fluid contamination affecting the switch signal
Less commonly, a faulty TCM that misinterprets a normal signal

How to diagnose and fix it

Scan all modules and record freeze-frame data for P1874 to confirm the fault is current and not history
Inspect the transmission wiring harness and connectors for chafing, corrosion, or loose pins, especially near the pass-through connector
Disconnect the TCC stator temperature switch and measure its resistance with a multimeter, comparing to GM specifications for the ambient temperature
Check the switch circuit for an open by measuring continuity from the switch connector to the TCM connector
Repair or replace any damaged wiring or terminals, then clear the code and verify the circuit voltage returns to normal
If the switch tests out of specification, replace the TCC stator temperature switch and reset the TCM adaptations
After repair, road-test the vehicle to confirm TCC lockup occurs and the code does not return

What the stator temp switch really does

Many technicians replace the TCM or transmission unnecessarily because they overlook a simple open in the stator switch circuit, which is often caused by a broken wire inside the transmission pan.
The TCC stator temperature switch is a thermistor-style sensor, so a high voltage code can also set if the switch is unplugged or if the transmission fluid is extremely cold during a scan.
A poor ground at the transmission case or a loose bellhousing bolt can create a high-voltage signal on this circuit, mimicking a failed switch.
This code does not always mean the torque converter is failing; it frequently sets from a corroded connector pin that costs little to repair.
On some GM models, the same circuit is shared with other temperature sensors, so a high signal can be caused by a short to voltage elsewhere in the harness.

Can I keep driving with P1874?

You can usually drive the vehicle with P1874 set, but avoid heavy towing or sustained high-speed driving because the torque converter clutch may not lock up, which can raise transmission fluid temperature. Have the circuit inspected soon to prevent unnecessary wear on the transmission.

Tools that help

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Guidance is general and written for GM vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.