What it means
The transmission control module monitors the transmission mode switch D circuit voltage. It sets this code when the signal rises above the expected range, indicating an electrical high condition in that circuit.
At a glance
- Usually lights the check-engine light
How it works
The transmission mode switch D is an electrical input the transmission control module uses to identify a selector or drive-mode state. P07D0 sets when the D signal rises above its expected range, which can occur if the circuit is connected to battery voltage or its supply wiring is damaged.
Common causes
Most likely first.
- Switch wire shorted to battery voltage
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
How to diagnose it
- Save freeze-frame data and compare the mode switch D live-data state with the selector position when the fault occurred.
- Inspect the D-circuit harness for pinching or damage where it could contact a battery-voltage source.
- Check connector pins for corrosion, looseness, or signs of an unwanted connection between the D signal and a power terminal.
- Using the wiring diagram, test the D signal for a short to battery voltage and check continuity through the circuit.
- If the harness and connectors pass, test the mode switch D and module input according to the manufacturer's procedure.
Common fixes
- Repair pinched D-circuit wiring contacting a power source.
- Clean or repair corroded, loose, or damaged connector terminals.
- Replace a mode switch D that fails its specified test.
- Repair the circuit or module input if testing identifies it as the source of the high signal.
Can I keep driving?
Limit driving if the transmission shifts harshly, delays, slips, or becomes stuck in one gear, since further slipping can damage internal parts. If it behaves normally, make only a short, cautious trip for diagnosis and stop if control or shifting becomes unreliable.
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.