P1903: Kickdown Solenoid Circuit Low Voltage
The P1903 code indicates that the powertrain control module (PCM) has detected a low voltage condition in the kickdown solenoid circuit. This solenoid is responsible for downshifting the transmission when the accelerator is fully depressed. Low voltage can be caused by a faulty solenoid, damaged wiring, poor electrical connections, or a weak battery/charging system. This condition may prevent proper downshifting, leading to reduced acceleration and potential transmission damage.
01. Most Common Causes
- Faulty kickdown solenoid
- Damaged or corroded wiring/connectors in the solenoid circuit
- Low battery voltage or charging system issue
- Blown fuse or relay related to the solenoid
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Poor acceleration or hesitation when pressing the accelerator fully
- Transmission fails to downshift properly
- Reduced fuel economy
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm the code and check for related transmission codes.
Step 2: Inspect the kickdown solenoid and its wiring for damage, corrosion, or loose connections.
Step 3: Test the solenoid resistance with a multimeter (compare to manufacturer specs).
Step 4: Check battery voltage and charging system output (should be 12.6V+ engine off, 13.5-14.5V running).
Step 5: If wiring and voltage are okay, replace the kickdown solenoid.
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 poor acceleration and may lead to transmission damage over time.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for parts and labor, depending on the vehicle and shop rates.