P1904: Kickdown Solenoid Circuit High Voltage
The P1904 code indicates that the powertrain control module (PCM) has detected a voltage level in the kickdown solenoid circuit that is higher than the specified range. The kickdown solenoid is responsible for downshifting the transmission when the accelerator is fully depressed, allowing for maximum acceleration. A high voltage condition can be caused by a short to power, a faulty solenoid, or a wiring issue. This code is often accompanied by transmission performance problems.
01. Most Common Causes
- Short to power in the kickdown solenoid circuit
- Faulty kickdown solenoid
- Damaged wiring or connectors
- Corroded or loose electrical connections
- Faulty PCM (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Transmission fails to downshift when accelerating hard
- Poor acceleration performance
- Transmission stuck in a single gear (limp mode)
03. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for any additional codes.
Step 2: Visually inspect the kickdown solenoid wiring and connectors for damage, corrosion, or loose connections.
Step 3: Test the kickdown solenoid resistance with a multimeter; compare to manufacturer specifications.
Step 4: Check for voltage at the solenoid connector with the ignition on; if voltage is above spec, trace the short to power.
Step 5: If all else is normal, test the PCM output and consider PCM replacement if necessary.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with this code as it can cause transmission shifting issues and potentially lead to further damage. Limp mode may activate, limiting speed and drivability.
How much does it cost to fix?▼
The cost to fix P1904 typically ranges from $50 to $150 for parts and labor, depending on whether the solenoid or wiring needs replacement. Diagnostic fees may be additional.