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P2738 — Pressure Control Solenoid F Control Circuit Low

Manufacturer-specificPowertrain (engine & transmission)

P2738 indicates the powertrain control module (PCM) or transmission control module (TCM) has detected a control-circuit voltage or current condition that is lower than expected for pressure control solenoid “F.” This usually points to excessive resistance, an open circuit, or a short to ground in the solenoid’s control wiring or the solenoid itself, which can disrupt normal hydraulic pressure regulation in the automatic transmission.

Symptoms

What causes it — most likely first

1. Failed pressure control solenoid F

The solenoid coil can develop an internal short, low resistance, or open circuit, causing the control-circuit current to read below the PCM’s expected threshold. This is the single most common root cause for a circuit-low code.

2. Wiring short to ground or open circuit

The control wire between the PCM/TCM and the solenoid may be chafed, pinched, or broken, creating a short to ground or an open that pulls circuit voltage low.

3. Poor electrical connection at the solenoid or harness connector

Corroded, bent, loose, or oil-contaminated pins and terminals can increase resistance or intermittently open the circuit, triggering a low-side fault.

4. Internal transmission harness or pass-through connector fault

Some transmissions route wiring through an internal harness or a case connector; damaged conductors inside the transmission can produce the same circuit-low signature.

5. PCM/TCM output driver failure

Although much less common than solenoid or wiring faults, a failed low-side driver inside the control module can set this code; it should be considered only after the solenoid, connectors, and wiring have been verified good.

How it's diagnosed

  1. Confirm the code with a scan tool and record freeze-frame data; check for related transmission, shift-solenoid, or pressure codes that may point to a broader electrical issue.
  2. Inspect the external wiring harness and connector for solenoid F for chafing, pin corrosion, terminal spread, oil intrusion, and connector-lock damage; repair any visible defects.
  3. Measure the resistance of pressure control solenoid F and compare it to the manufacturer specification; also test the solenoid for shorts to ground and for an open coil.
  4. With the key on and using a wiring diagram, verify that the control circuit has proper power, ground, and PCM/TCM command signal at the solenoid connector; a test light or oscilloscope can show whether the PCM is actually commanding the solenoid.
  5. If the solenoid, wiring, and connectors all test normal and the code returns, evaluate the PCM/TCM control output before condemning the module.

Code facts & related codes

SystemPowertrain (engine & transmission)
StandardizationManufacturer-specific (P1/B1/C1/U1)
Related codesP2730 — Pressure Control Solenoid E Control CiP2731 — Pressure Control Solenoid FP2732 — Pressure Control Solenoid F PerformancP2733 — Pressure Control Solenoid F StuckP2734 — Pressure Control Solenoid F ElectricalP2735 — Pressure Control Solenoid F Intermitte

Frequently asked

Can I keep driving with P2738?

It is not advisable. Abnormal line pressure can cause harsh shifting, clutch slippage, and accelerated transmission wear; continuing to drive may lead to more expensive mechanical damage.

Is the problem the solenoid or the wiring?

Either is possible. The solenoid itself fails most often, but a short-to-ground, open wire, or bad connector can set the same code, so both must be tested rather than assumed.

Do I need a new PCM/TCM for P2738?

Usually no. PCM/TCM failure is one of the least likely causes for this code; replacing the module is commonly misdiagnosed. Most cases are resolved by replacing the solenoid or repairing the wiring/connector.

Where is pressure control solenoid F located?

It is mounted on or inside the transmission valve body. Access normally requires lowering the transmission pan and, on some designs, partial valve-body disassembly.