Code
P0745
HUMMER
P — Powertrain
Pressure Control Solenoid Malfunction
Views:
UK: 9
EN: 14
RU: 21
AI status
Completed
Completed
100%
Causes
- Faulty pressure control solenoid (electrical or mechanical failure)
- Damaged wiring harness or poor connector connection to the solenoid
- Low, dirty, or contaminated transmission fluid
- Valve body contamination, sticking valve, or internal hydraulic fault
- Faulty transmission control module (TCM/PCM) or incorrect software
- Intermittent connectors or corrosion at pins
Symptoms
- MIL/Check Engine Light illuminated with stored P0745
- Harsh or delayed shifts, slipping, or erratic shift points
- Transmission in limp/limited-gear mode
- Reduced fuel economy and poor drivability
- Transmission fluid overheating or abnormal fluid noise
What to check
- Scan for P0745 plus any additional transmission codes and view freeze-frame data
- Check transmission fluid level, color, and smell (burnt or contaminated fluid)
- Visually inspect wiring and connector for corrosion, breaks, or pin damage
- Measure solenoid resistance and compare to specification
- Check for power and ground at the solenoid connector with key on
- Use a scan tool to command the solenoid and observe response in live data
Signal parameters
- Typical solenoid coil resistance: ~10–40 ohms (vehicle-specific; consult service manual)
- Supply voltage: ~12 V battery at relay/fuse, switched by TCM to ground or PWM
- Control signal: PWM duty cycle varies 0–100% to modulate line pressure
- PWM frequency commonly in the tens to a few hundred Hz (vehicle-specific)
- Expected behavior: resistance within spec, proper supply voltage present, and commanded PWM changes duty cycle and affects line pressure/live-data values
Diagnostic algorithm
- Retrieve all codes and freeze-frame using a factory-level scan tool; record live data for transmission pressure and solenoid status.
- Inspect transmission fluid level and condition; top/replace fluid if severely low/contaminated before further testing.
- Visually inspect wiring and connector at the solenoid for corrosion, bent pins, or damage; repair any issues.
- With connector disconnected, measure solenoid coil resistance and compare to service spec. Check for short to ground or open circuit.
- With key on, check for battery voltage at the power feed and a good ground reference. Re-pin backprobe to observe control signal while commanding solenoid with a scan tool.
- Command the solenoid on/off with a scan tool and observe live-data changes (line pressure, duty cycle). Use an oscilloscope if available to verify PWM waveform.
- If electrical tests are good but symptoms persist, perform a transmission line pressure test and compare to spec; suspect valve body or hydraulic issue if pressure incorrect.
- If solenoid is out of spec electrically, replace solenoid and retest. If new solenoid fails or wiring checks fail, trace harness to TCM and check connector pins and grounds.
- If wiring and solenoid are good but fault returns, consider TCM output driver failure or internal transmission valve body repair; consult service manual for module/component replacement and programming.
- Clear codes and perform a controlled test drive; verify that the code does not return and that shift quality is restored.
Likely causes
- Solenoid electrical failure (coil open/short) — most common
- Wiring short, open, or high resistance in harness/connector
- Contaminated or low transmission fluid causing valve sticking
- Valve body internal fault or stuck pressure regulator valve
- Control module output driver fault (less common)
Fault status
Status
MIL illuminated. Transmission may go into limp mode and exhibit harsh or erratic shifting. Code P0745 stored in memory.
Repair difficulty: Medium
Diagnostic time: 1-3 hours
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