What it means
The transmission range control module communication circuit signal is above the expected level. The exact cause depends on the vehicle's communication circuit.
At a glance
- Usually lights the check-engine light
How it works
The transmission range control module communicates with other vehicle modules over a vehicle network. P07F4 sets when the communication circuit signal is higher than expected; a bus short to battery voltage or a network routing fault can cause it, depending on the vehicle's design.
Common causes
Most likely first.
- Bus shorted to battery voltage
- Gateway module routing CAN messages incorrectly
- CAN terminating resistor (120 Ω) drifted out of spec
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
- Record freeze-frame data and scan all modules for network codes to identify which devices report a high communication signal or missing messages.
- Check whether the range control module responds consistently to the scan tool and whether other modules lose communication at the same time.
- Inspect accessible network wiring and connectors for pinched insulation, corrosion, loose pins, or contact with a powered wire.
- Check the range control module's power and ground circuits to rule out a supply problem affecting its network signal.
- Test the communication bus for a short to battery voltage and inspect network termination only as directed by the vehicle's diagnostic procedure.
- If the wiring and termination check out, investigate gateway routing and the range control module using the manufacturer's diagnostic steps.
Common fixes
- Repair a communication wire shorted to battery voltage.
- Repair pinched or damaged network wiring and secure it away from powered wires.
- Clean or replace damaged network connector terminals.
- Correct a confirmed gateway routing fault or network termination fault.
- Replace the range control module only after verifying the bus, power, and ground.
Can I keep driving?
If shifting is abnormal or the transmission enters limp mode, avoid unnecessary driving until the high communication signal is diagnosed. Network faults can interrupt range information and disrupt transmission control.
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.