What it means
Same as P05D1 on switch B. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
How it works
Switch B sends a mode-selection input to the vehicle controller through its own signal circuit. P05D5 sets when the switch B signal is abnormally low, consistent with a short to ground or another fault pulling that input down.
Common causes
Most likely first.
- Signal shorted to ground
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
Symptoms
- Drive-mode selection may be unavailable or unchanged
- A drive-mode warning or check-engine light may illuminate
How to diagnose it
- Monitor switch B's reported state with a scan tool while operating it and check whether the input remains low.
- Inspect switch B's connector and wiring for chafing, moisture, corrosion, or pushed-back pins that may ground the signal.
- Use the wiring diagram to test the switch B signal for a short to ground, isolating harness sections according to service information.
- Wiggle the switch B harness while watching live data to identify an intermittent ground fault.
- If the wiring is sound, test switch B and its circuit connections against the manufacturer's specification.
Common fixes
- Clean, dry, and reconnect the switch B connector or restore a pushed-back terminal.
- Repair chafed switch B signal wiring that is contacting ground.
- Replace switch B if testing confirms it is pulling the signal low.
- Repair a confirmed fault in the controller input circuit.
Can I keep driving?
The vehicle is generally driveable if it runs and responds normally, but switch B may not change the drive mode. Do not depend on selecting a special mode for low-traction conditions.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.