P0790: Normal/Performance Switch Circuit Malfunction
The P0790 code indicates a malfunction in the normal/performance switch circuit, which is part of the transmission control system. This switch allows the driver to select between normal and performance shift modes. The Powertrain Control Module (PCM) detects an electrical fault, such as an open or short circuit, in the switch or its wiring. This can affect shift timing and transmission behavior.
01. Most Common Causes
- Faulty normal/performance switch
- Damaged wiring or connector in the switch circuit
- Corrosion or poor electrical connection
- Blown fuse related to the transmission control system
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Transmission stuck in one shift mode (normal or performance)
- Harsh or delayed shifts
- Reduced fuel economy
03. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for other transmission-related codes.
Step 2: Visually inspect the normal/performance switch and its wiring for damage, corrosion, or loose connections.
Step 3: Test the switch with a multimeter to verify proper resistance and continuity according to manufacturer specs.
Step 4: Check the fuse for the transmission control system and replace if blown.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is generally safe for short distances, but the transmission may not shift optimally, potentially causing drivability issues or further damage. It's best to diagnose and repair promptly.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150, including parts (switch) and labor. If wiring repair is needed, costs may be higher.