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Home / DTC / P0779 — Pressure Control Solenoid B Intermittent

P0779 — Pressure Control Solenoid B Intermittent

Detailed page for trouble code P0779.

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22,491specific
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P0779

Generic P — Powertrain

Pressure Control Solenoid B Intermittent

Brand: Generic
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Intermittent open or short in wiring to pressure control solenoid B
  • Corroded or loose connector/pins at the solenoid or TCM
  • Faulty pressure control solenoid B (coil intermittent)
  • Poor or intermittent ground or power supply to the solenoid circuit
  • Contaminated or degraded transmission fluid causing solenoid sticking
  • Faulty TCM/PCM output driver or internal intermittent module fault

Symptoms

  • MIL (Check Engine / Transmission) illuminated
  • Intermittent harsh or erratic shifting
  • Delayed engagement into gear or slipping
  • Transmission may enter limp/limited gear mode intermittently
  • Poor drivability or reduced fuel economy when fault is active
  • Occasional unusual transmission noise if line pressure fluctuates

What to check

  • Read freeze frame and live data with a capable scan tool; confirm P0779 and any related codes
  • Attempt to reproduce symptom/monitor solenoid status while driving or during a self-test
  • Visually inspect wiring and connectors for damage, corrosion, or loose pins at solenoid and TCM
  • Back-probe solenoid connector and wiggle wiring while observing data for intermittent changes
  • Measure solenoid coil resistance with ohmmeter (compare to factory spec)
  • Check supply voltage and ground at the solenoid with key ON and during commanded activation

Signal parameters

  • Solenoid coil resistance: varies by vehicle (typically ~10–40 ohms). Consult factory spec for exact value.
  • Supply voltage: battery voltage present at supply pin with key ON (approx. 11–14 V)
  • Control signal: TCM commonly uses a PWM ground or switched supply; duty cycle changes to control pressure (0–100% duty)
  • PWM frequency: typically tens to a few hundred Hz (varies by manufacturer)
  • Intermittent fault signature: open/short spikes, loss of PWM signal, erratic duty or voltage drop when wiggle-testing

Diagnostic algorithm

  1. Verify code and note freeze frame/live data. Check for multiple related transmission DTCs.
  2. Inspect fluid level/condition. Replace fluid/filter if contaminated before replacing electrical components.
  3. Visually inspect solenoid connector and wiring; repair obvious damage, corrosion, or loose pins.
  4. With connector disconnected, measure solenoid coil resistance and compare to spec. If open or out of range, replace solenoid.
  5. Reconnect and back-probe supply and control pins. Check for battery voltage at supply pin and proper grounding or PWM when commanded using a scan tool.
  6. Wiggle harness and connectors while monitoring voltage/resistance/live data to reproduce intermittent behavior. Repair any intermittent wiring faults discovered.
  7. Use an oscilloscope to inspect PWM waveform for noise, dropouts, or driver issues. If waveform is abnormal at the TCM connector, suspect the module.
  8. If wiring and solenoid test good, check TCM grounds and power feeds. If all external circuits test good, consider TCM driver fault — verify with manufacturer procedure before replacement.
  9. After repairs, clear codes and perform a road test or re-run the self-tests to confirm the fault does not return.

Likely causes

  • Damaged/chafed harness where it flexes (causes intermittent contact)
  • Corroded connector pins at the solenoid or inline harness connector
  • Solenoid coil beginning to fail (opens intermittently under heat/vibration)
  • Loose ground or supply circuit connection
  • TCM driver transistor intermittent (less common than wiring/solenoid issues)

Fault status

⚠️ Status
Intermittent fault detected in Transmission Pressure Control Solenoid B circuit. PCM/TCM observed inconsistent/open/shorted signal to solenoid B which can cause erratic line pressure and shifting. Further electrical and hydraulic diagnosis required.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours (varies by vehicle complexity and accessibility)

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Code

P0779

LAND ROVER P — Powertrain

Fluid temperature measurement system intermittent transmission

Brand: LAND ROVER
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Intermittent open or short in wiring to pressure control solenoid B
  • Corroded or loose connector/pins at the solenoid or TCM
  • Faulty pressure control solenoid B (coil intermittent)
  • Poor or intermittent ground or power supply to the solenoid circuit
  • Contaminated or degraded transmission fluid causing solenoid sticking
  • Faulty TCM/PCM output driver or internal intermittent module fault

Symptoms

  • MIL (Check Engine / Transmission) illuminated
  • Intermittent harsh or erratic shifting
  • Delayed engagement into gear or slipping
  • Transmission may enter limp/limited gear mode intermittently
  • Poor drivability or reduced fuel economy when fault is active
  • Occasional unusual transmission noise if line pressure fluctuates

What to check

  • Read freeze frame and live data with a capable scan tool; confirm P0779 and any related codes
  • Attempt to reproduce symptom/monitor solenoid status while driving or during a self-test
  • Visually inspect wiring and connectors for damage, corrosion, or loose pins at solenoid and TCM
  • Back-probe solenoid connector and wiggle wiring while observing data for intermittent changes
  • Measure solenoid coil resistance with ohmmeter (compare to factory spec)
  • Check supply voltage and ground at the solenoid with key ON and during commanded activation

Signal parameters

  • Solenoid coil resistance: varies by vehicle (typically ~10–40 ohms). Consult factory spec for exact value.
  • Supply voltage: battery voltage present at supply pin with key ON (approx. 11–14 V)
  • Control signal: TCM commonly uses a PWM ground or switched supply; duty cycle changes to control pressure (0–100% duty)
  • PWM frequency: typically tens to a few hundred Hz (varies by manufacturer)
  • Intermittent fault signature: open/short spikes, loss of PWM signal, erratic duty or voltage drop when wiggle-testing

Diagnostic algorithm

  1. Verify code and note freeze frame/live data. Check for multiple related transmission DTCs.
  2. Inspect fluid level/condition. Replace fluid/filter if contaminated before replacing electrical components.
  3. Visually inspect solenoid connector and wiring; repair obvious damage, corrosion, or loose pins.
  4. With connector disconnected, measure solenoid coil resistance and compare to spec. If open or out of range, replace solenoid.
  5. Reconnect and back-probe supply and control pins. Check for battery voltage at supply pin and proper grounding or PWM when commanded using a scan tool.
  6. Wiggle harness and connectors while monitoring voltage/resistance/live data to reproduce intermittent behavior. Repair any intermittent wiring faults discovered.
  7. Use an oscilloscope to inspect PWM waveform for noise, dropouts, or driver issues. If waveform is abnormal at the TCM connector, suspect the module.
  8. If wiring and solenoid test good, check TCM grounds and power feeds. If all external circuits test good, consider TCM driver fault — verify with manufacturer procedure before replacement.
  9. After repairs, clear codes and perform a road test or re-run the self-tests to confirm the fault does not return.

Likely causes

  • Damaged/chafed harness where it flexes (causes intermittent contact)
  • Corroded connector pins at the solenoid or inline harness connector
  • Solenoid coil beginning to fail (opens intermittently under heat/vibration)
  • Loose ground or supply circuit connection
  • TCM driver transistor intermittent (less common than wiring/solenoid issues)

Fault status

⚠️ Status
Intermittent fault detected in Transmission Pressure Control Solenoid B circuit. PCM/TCM observed inconsistent/open/shorted signal to solenoid B which can cause erratic line pressure and shifting. Further electrical and hydraulic diagnosis required.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours (varies by vehicle complexity and accessibility)

Similar codes

P0776 P0777 P0778 P0757 P0705
320

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LAND ROVER

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