P07D1: Transmission Mode Switch E Circuit

What it means

A fault was detected in the transmission mode switch E circuit.

At a glance

• Usually lights the check-engine light

How it works

Transmission mode switch E is a separate electrical input used by the transmission control module to recognize a selector or drive-mode state. P07D1 identifies a fault in the E circuit, but does not specify whether its signal is too high, too low, open, or shorted.

Common causes

Most likely first.

1. Faulty transmission mode switch or selector
2. Open or shorted switch wiring
3. Loose, damaged, or corroded connector
4. Fault in the transmission control module input circuit

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

1. Record freeze-frame data and watch the mode switch E live data while selecting the available modes, noting whether the indicated state changes.
2. Inspect the E switch, its connector, and the nearby harness for damage, looseness, or corrosion.
3. Use the wiring diagram to check the E circuit for an open or short and verify continuity between the switch and module.
4. Test the E switch output through its operating positions against the manufacturer's procedure.
5. If the switch and wiring pass, check the transmission control module input and its connector for a circuit fault.

Common fixes

• Secure or repair a loose, damaged, or corroded E-circuit connector.
• Repair an open or short in the E-circuit wiring.
• Replace the mode switch or selector if it fails its specified test.
• Repair the module input circuit if testing confirms the fault is there.

Can I keep driving?

If shifting is harsh, delayed, slipping, or limited to one gear, avoid long trips and heavy loads because continued slipping can damage the transmission. If shifting remains normal, drive cautiously only as needed to arrange diagnosis.