Pressure Control Solenoid C Electrical
Code P0798 indicates an electrical problem with the Pressure Control Solenoid C circuit, which controls transmission fluid pressure during shifts. This causes the transmission control module to detect an open, short, or out-of-range voltage condition in the solenoid circuit, often triggering limp mode to protect the transmission.
What You Might Notice
- Check Engine Light illuminated
- Vehicle enters limp mode or reduced power mode
- Transmission slips during gear shifts
- Transmission overheating
- Decreased fuel economy
Most Common Causes
- 1
Defective Pressure Control Solenoid C
The solenoid coil may be open, shorted, or mechanically stuck, preventing proper pressure control during transmission operation.
- 2
Corroded or damaged solenoid connector
Corrosion, moisture, or loose connections at the solenoid electrical connector can cause intermittent or complete loss of signal to the solenoid.
- 3
Faulty wiring to Pressure Control Solenoid C
Damaged, pinched, or shorted wiring harness between the PCM and solenoid can prevent proper electrical communication.
- 4
Dirty transmission fluid or clogged filter
Contaminated fluid or a restricted filter can affect solenoid operation and cause the PCM to detect abnormal pressure readings.
How to Diagnose It
- 1
Check Defective Pressure Control Solenoid C — The solenoid coil may be open, shorted, or mechanically stuck, preventing proper pressure control during transmission operation.
- 2
Check Corroded or damaged solenoid connector — Corrosion, moisture, or loose connections at the solenoid electrical connector can cause intermittent or complete loss of signal to the solenoid.
- 3
Check Faulty wiring to Pressure Control Solenoid C — Damaged, pinched, or shorted wiring harness between the PCM and solenoid can prevent proper electrical communication.
- 4
Check Dirty transmission fluid or clogged filter — Contaminated fluid or a restricted filter can affect solenoid operation and cause the PCM to detect abnormal pressure readings.
How to Fix It
- 1
Replace Pressure Control Solenoid C
Locate and remove the defective solenoid, clean the mounting area, install the new solenoid with proper torque specifications, and reconnect the electrical connector securely.
- 2
Inspect and repair solenoid connector and wiring
Check the connector for corrosion, moisture, or damage; clean contacts or replace the connector as needed. Inspect the wiring harness for damage, repair or replace any faulty wiring sections.
- 3
Perform transmission fluid and filter service
Drain old transmission fluid, replace the transmission filter, install new fluid to the correct level, and recheck for proper solenoid operation.
- 4
Test and reprogram PCM if necessary
After repairs, use a diagnostic scanner to clear the code and verify solenoid resistance and voltage readings are within specification. If readings remain abnormal, the PCM may require reprogramming or replacement.
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