Code
P0799
Generic
P — Powertrain
Pressure Control Solenoid C Intermittent
Views:
UK: 14
EN: 18
RU: 18
AI status
Completed
Completed
100%
Causes
- Damaged, corroded or loose connector for pressure control solenoid C
- Broken, chafed or shorted wiring in the solenoid circuit
- Failing or sticking pressure control solenoid C
- Contaminated transmission fluid or clogged valve body passage
- Poor ground or low reference voltage to the solenoid
- Intermittent TCM/PCM driver output or internal controller fault
Symptoms
- Check Engine or Transmission warning lamp illuminated
- Erratic or harsh shifting, delayed shifts or slipping
- Transmission may go into limp/backup mode
- Intermittent loss of proper line pressure control
- Multiple transmission-related DTCs may be present
What to check
- Read freeze-frame and live data with a scan tool; confirm P0799 and note conditions
- Visually inspect solenoid connector and wiring for corrosion, damage, or looseness
- Wiggle harness/connectors while monitoring codes and live data to reproduce the intermittent fault
- Check transmission fluid level and condition (burnt smell, debris)
- Measure solenoid coil resistance at the connector with connector disconnected
- Back-probe power and ground at the solenoid while operating to verify steady supply and switching
Signal parameters
- Solenoid coil resistance: typically low ohms (varies by design) — commonly in the range ~5–50 Ω; consult vehicle spec
- Supply voltage: nominal battery/ignition voltage (~12 V) on the power feed
- Control: modulated by PCM/TCM using PWM; duty cycle varies 0–100% to control pressure
- PWM frequency: commonly in the range ~50–200 Hz (varies by manufacturer)
- Expected behavior: steady PWM and stable resistance; intermittent open/short or erratic duty indicates fault
Diagnostic algorithm
- Retrieve DTCs and freeze-frame data; note operating conditions when fault set (temp, RPM, gear).
- Clear codes and road-test to try to reproduce. Monitor live data for pressure, solenoid status, and shifts.
- Visually inspect connector and wiring to solenoid C. Repair any corrosion, bent pins, or damage.
- With ignition off, disconnect solenoid connector and measure coil resistance; compare to spec. Replace if open or out of range.
- With connector connected, back-probe power and ground while operating; confirm steady battery voltage on power feed and good ground.
- Use an oscilloscope or quality scan tool to observe PWM control signal at the solenoid while shifting; look for intermittent loss, noise, or unexpected duty changes.
- Perform a wiggle test of the harness/connectors while monitoring the circuit to find intermittent wiring faults.
- If electrical checks pass, inspect transmission fluid, filter and valve body for contamination or sticking valve that can mimic solenoid issues.
- If possible, swap solenoid C with another identical solenoid position (if same part and wiring) to see if code follows the solenoid.
- If solenoid and wiring test good but intermittent fault persists, consider TCM/PCM driver failure and follow manufacturer procedures for module testing or replacement.
- Safety note: support vehicle securely and be cautious of hot fluids when checking transmission components.
Likely causes
- Loose or corroded connector at solenoid C
- Wiring harness damage (chafe, break, or intermittent short)
- Failing solenoid (intermittent internal contact or coil)
- Contaminated fluid/valve body restricting solenoid movement
- Poor ground or intermittent supply voltage from PCM/TCM
Fault status
Status
P0799 — Pressure Control Solenoid C Intermittent: intermittent/open/short or erratic signal detected in transmission pressure control solenoid C circuit.
Repair difficulty: Medium
Diagnostic time: 0.5-3 hours
Similar codes
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email
Code
P0799
LAND ROVER
P — Powertrain
Control Solenoid intermittent C pressure
Views:
UK: 5
EN: 7
RU: 7
AI status
Completed
Completed
100%
Causes
- Damaged, corroded or loose connector for pressure control solenoid C
- Broken, chafed or shorted wiring in the solenoid circuit
- Failing or sticking pressure control solenoid C
- Contaminated transmission fluid or clogged valve body passage
- Poor ground or low reference voltage to the solenoid
- Intermittent TCM/PCM driver output or internal controller fault
Symptoms
- Check Engine or Transmission warning lamp illuminated
- Erratic or harsh shifting, delayed shifts or slipping
- Transmission may go into limp/backup mode
- Intermittent loss of proper line pressure control
- Multiple transmission-related DTCs may be present
What to check
- Read freeze-frame and live data with a scan tool; confirm P0799 and note conditions
- Visually inspect solenoid connector and wiring for corrosion, damage, or looseness
- Wiggle harness/connectors while monitoring codes and live data to reproduce the intermittent fault
- Check transmission fluid level and condition (burnt smell, debris)
- Measure solenoid coil resistance at the connector with connector disconnected
- Back-probe power and ground at the solenoid while operating to verify steady supply and switching
Signal parameters
- Solenoid coil resistance: typically low ohms (varies by design) — commonly in the range ~5–50 Ω; consult vehicle spec
- Supply voltage: nominal battery/ignition voltage (~12 V) on the power feed
- Control: modulated by PCM/TCM using PWM; duty cycle varies 0–100% to control pressure
- PWM frequency: commonly in the range ~50–200 Hz (varies by manufacturer)
- Expected behavior: steady PWM and stable resistance; intermittent open/short or erratic duty indicates fault
Diagnostic algorithm
- Retrieve DTCs and freeze-frame data; note operating conditions when fault set (temp, RPM, gear).
- Clear codes and road-test to try to reproduce. Monitor live data for pressure, solenoid status, and shifts.
- Visually inspect connector and wiring to solenoid C. Repair any corrosion, bent pins, or damage.
- With ignition off, disconnect solenoid connector and measure coil resistance; compare to spec. Replace if open or out of range.
- With connector connected, back-probe power and ground while operating; confirm steady battery voltage on power feed and good ground.
- Use an oscilloscope or quality scan tool to observe PWM control signal at the solenoid while shifting; look for intermittent loss, noise, or unexpected duty changes.
- Perform a wiggle test of the harness/connectors while monitoring the circuit to find intermittent wiring faults.
- If electrical checks pass, inspect transmission fluid, filter and valve body for contamination or sticking valve that can mimic solenoid issues.
- If possible, swap solenoid C with another identical solenoid position (if same part and wiring) to see if code follows the solenoid.
- If solenoid and wiring test good but intermittent fault persists, consider TCM/PCM driver failure and follow manufacturer procedures for module testing or replacement.
- Safety note: support vehicle securely and be cautious of hot fluids when checking transmission components.
Likely causes
- Loose or corroded connector at solenoid C
- Wiring harness damage (chafe, break, or intermittent short)
- Failing solenoid (intermittent internal contact or coil)
- Contaminated fluid/valve body restricting solenoid movement
- Poor ground or intermittent supply voltage from PCM/TCM
Fault status
Status
P0799 — Pressure Control Solenoid C Intermittent: intermittent/open/short or erratic signal detected in transmission pressure control solenoid C circuit.
Repair difficulty: Medium
Diagnostic time: 0.5-3 hours
Similar codes
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email