1-4 Upshift (Skip Shift) Solenoid Control Circuit
The P0803 code indicates that the powertrain control module (PCM) has detected an electrical malfunction in the 1-4 upshift (skip shift) solenoid control circuit. This code is set when the PCM detects voltage or resistance levels in the skip shift solenoid circuit that fall outside of the expected manufacturer parameters.
This issue is not a safety hazard and will not strand the vehicle. It primarily affects the fuel-economy-driven skip shift feature, though the check engine light will remain illuminated.
Common symptoms
- Illuminated Check Engine Light (MIL)
- Inability of the transmission to force the 1-4 skip shift under light acceleration
- Transmission shifts normally through all gears without the factory restriction
- Skip shift indicator light on the dash may fail to illuminate or operate erratically
- Blown fuse related to the transmission or skip shift circuit
Likely causes
- Faulty 1-4 upshift (skip shift) solenoid
- Damaged, corroded, or disconnected wiring in the skip shift solenoid circuit
- Poor electrical connection at the skip shift solenoid connector
- Blown fuse or tripped fusible link in the transmission control circuit
- Aftermarket skip shift eliminator installed incorrectly or failing
- Faulty Powertrain Control Module (PCM) (rare)
What to check before replacing parts
Inspect the wiring and connector at the skip shift solenoid on the transmission.
Look for: Frayed wires, melted insulation, or corrosion inside the connector pins that would cause high resistance or an open circuit.
Check the transmission and skip shift circuit fuses in the fuse box.
Look for: A blown fuse, which indicates a short circuit in the solenoid or its wiring harness.
Test the skip shift solenoid resistance with a digital multimeter.
Look for: Resistance values outside the manufacturer's specified range, indicating an internally shorted or open solenoid.
Check for voltage and ground at the solenoid connector while commanding the solenoid via a scan tool.
Look for: Lack of battery voltage or a missing ground signal from the PCM, indicating a wiring issue upstream or a blown fuse.
Command the solenoid on and off using a bi-directional scan tool.
Look for: An audible click from the solenoid; if it clicks but the code persists, suspect an intermittent wiring issue or a rare PCM fault.
This page explains the generic P0803 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
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