P2738

Code

Generic P — Powertrain

Pressure Control Solenoid F Control Circuit Low

Brand: Generic

Type: P — Powertrain

Views: UK: 22 EN: 37 RU: 24

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Page language: EN

Causes

Open or shorted wiring in the solenoid control circuit
Poor or corroded connector at the solenoid or TCM/PCM
Faulty pressure control solenoid F (internal short or open)
Low battery or poor system voltage/ground
Blown fuse or fusible link supplying transmission solenoids
Water intrusion or corrosion in the valve body or harness

Symptoms

MIL (check engine light) illuminated
Transmission may enter limp/default mode
Harsh, delayed, or erratic shifting
Reduced performance or inability to engage certain gears
Stored transmission-related trouble codes and a possible fail-safe shift strategy

What to check

Retrieve freeze frame and live data with a scan tool; confirm P2738 is current and note operating conditions when set
Visually inspect wiring and connectors to solenoid F and the TCM for damage, corrosion, or water intrusion
Check transmission-related fuses and battery voltage; ensure good battery and chassis/engine grounds
Backprobe the solenoid connector with key ON and while commanding the solenoid with a scanner to observe voltage and/or PWM
Measure solenoid coil resistance (compare to spec or similar solenoids) and check for short to ground or to battery
Wiggle harness while monitoring signal to reproduce intermittent faults

Signal parameters

Supply/reference: typically battery/ignition 12V supply to solenoid bank (verify vehicle-specific)
Control: most modern transmission pressure solenoids are low-side switched by the TCM using PWM — expected duty cycle 0–100% depending on command
Typical coil resistance (varies by vehicle): roughly 10–50 ohms; check specific service data
When commanded ON (activated) expected: measurable PWM or change in voltage; when commanded OFF expected: close to supply voltage on harness side or low/no ground depending on circuit design — consult vehicle-specific wiring
A ‘low’ circuit fault means the measured voltage on the control lead is lower than expected (often near 0V) when the module expects a higher level or open state

Diagnostic algorithm

Verify code: connect scan tool, read codes and freeze-frame, attempt to recreate conditions that set the code.
Visual inspection: examine the solenoid connector, harness, and transmission case area for damage, corrosion, or fluid intrusion.
Check fuses and battery: confirm battery voltage and transmission/fusebox fuses are intact and connections tight.
Backprobe and test at rest: with ignition ON (engine OFF), backprobe the solenoid connector. Measure coil resistance between signal and supply/ground and compare to spec.
Command test: use a scan tool to command solenoid F ON and OFF while monitoring voltage/PWM at the connector. Note behavior and response.
Continuity and shorts: disconnect solenoid and check continuity between the control wire and TCM; check for short to ground or battery.
Wiggle and stress test: with connector engaged and tool commanding, wiggle harness and connectors to identify intermittent faults.
Component substitution: if wiring checks good, replace the solenoid and retest. If fault remains and wiring is verified, consider TCM replacement/repair.
Clear codes and road-test: after repairs, clear codes and perform a road test under conditions that previously set the fault to confirm repair.

Likely causes

Damaged pin, bent terminal, or corroded connector at the solenoid
Chafed harness causing a short to ground
Failed solenoid coil (open or internally shorted)
Weak or missing ground at transmission or TCM
Blown fuse or poor battery connection

Fault status

⚠️ Status

MIL illuminated; transmission control module has stored P2738 and likely recorded freeze-frame data. The TCM may apply limp-home strategy to protect transmission operation until the fault is resolved.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours