What Does P0971 Mean?
The TCM has detected that the Pressure Control Solenoid C (PCS-C) circuit voltage is consistently higher than the commanded value, indicating a short to battery voltage or an open ground return path. The solenoid cannot be properly de-energized or modulated by the TCM. Depending on how PCS-C is used in the specific transmission, this may cause low apply pressure, clutch slippage, torque converter shudder, or limp mode engagement.
Safety Warning
Low or uncontrolled pressure from a stuck-high solenoid circuit can cause clutch slippage and rapid fluid overheating. If slipping is observed, stop driving immediately and have the vehicle towed to prevent catastrophic transmission damage.
Common Causes
35%
Open or high-resistance ground path in the PCS-C circuit
25%
Short to battery voltage in the PCS-C wiring harness
20%
Corroded or backed-out ground terminal at the transmission case connector
15%
PCS-C solenoid with an open winding on the ground side
5%
TCM PCS-C driver stuck high
Diagnostic Steps
1
Measure PCS-C solenoid resistance at the transmission connector — should be within the 4-8 ohm specification. An excessively high or open reading may indicate an open ground leg within the solenoid.
2
With the transmission connector disconnected, measure voltage on the PCS-C wire at the TCM connector with key on. Constant battery voltage with no load indicates a possible short to B+ or a stuck TCM driver.
3
Verify ground path continuity from the PCS-C ground pin through the full circuit back to the TCM ground reference. Any break in the ground path will produce a high circuit voltage reading.
4
Inspect the case connector ground pins for corrosion, looseness, or physical damage. Verify external harness ground splices are intact.
5
If wiring and solenoid test normally, command PCS-C on/off with the scan tool and monitor actual circuit behavior at the TCM to confirm proper driver function.
Estimated Repair Cost
$200 - $1,400
Parts + labor, varies by vehicle and location
The TCM has detected that the Pressure Control Solenoid C (PCS-C) circuit voltage is consistently higher than the commanded value, indicating a short to battery voltage or an open ground return path. The solenoid cannot be properly de-energized or modulated by the TCM. Depending on how PCS-C is used...
The most common cause of P0971 (Pressure Control Solenoid "C" Control Circuit High) is: Open or high-resistance ground path in the PCS-C circuit
Typical repair costs for P0971 range from $200 to $1,400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Low or uncontrolled pressure from a stuck-high solenoid circuit can cause clutch slippage and rapid fluid overheating. If slipping is observed, stop driving immediately and have the vehicle towed to prevent catastrophic transmission damage.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0971 to identify the root cause.
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Quick Info
Category
Powertrain
System
Automatic Transmission / Transaxle
Difficulty
Type
Generic (SAE)
Recommended Tools
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