What it means
The control module monitors the transmission mode switch F circuit signal. It sets this code when the signal is higher than the expected range.
At a glance
- Usually lights the check-engine light
How it works
The transmission mode switch F is an electrical input the transmission control module uses to recognize a selector or drive-mode state. P07D6 sets when the F signal rises above its expected range, which can result from a short to battery voltage or a supply wire contacting the signal circuit.
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 mode switch F live data with the selected mode to determine when the high signal appears.
- Inspect the F-circuit harness for pinching or damage where it could contact battery-voltage wiring.
- Check the F connector for corrosion, loose pins, or terminals that could bridge the signal to a powered circuit.
- Use the wiring diagram to test the F signal for a short to battery voltage and verify circuit continuity.
- If wiring and connectors pass, test the F switch and module input using the manufacturer's procedure.
Common fixes
- Repair F-circuit wiring pinched against a power source.
- Clean or repair corroded, loose, or damaged connector terminals.
- Replace the mode switch F if it fails its specified test.
- Repair the module input circuit if tests show the high signal originates there.
Can I keep driving?
If the transmission shifts harshly, slips, or is stuck in one gear, avoid driving farther than necessary because continued slipping can damage internal components. If it shifts normally, make only a short, cautious trip to have the fault diagnosed.
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.