What it means
The auxiliary transmission fluid pump control module feedback signal is faulty or missing. This does not by itself establish whether the fault is in the signal wiring or the module.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The auxiliary transmission pump control module operates the pump and sends feedback so the vehicle's control system can confirm its status. The system monitors whether that feedback signal is present. This code sets when the signal is missing or faulty, but it does not by itself show whether the cause is wiring, a connector, or the control module.
Common causes
Most likely first.
- Open or shorted feedback wiring
- Poor connector connection
- Faulty pump control module
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 review live data for pump module feedback and pump commands to see when the signal disappears.
- Inspect the pump control module connector and feedback wiring for loose pins, corrosion, damaged insulation, or a harness pulled tight or chafed.
- Check the feedback circuit for continuity and shorts using the manufacturer's wiring information and procedure.
- If supported by the scan tool, command the auxiliary pump and observe whether feedback appears or changes with the command.
- Check module power and ground connections according to the manufacturer's procedure.
- If wiring, power, and ground are sound but feedback remains absent, diagnose the pump control module.
Common fixes
- Reconnect or repair a loose, corroded, or damaged feedback connector.
- Repair an open or short in the feedback wiring.
- Repair a faulty module power or ground connection.
- Replace the pump control module if testing confirms it is not providing feedback.
Can I keep driving?
Avoid driving if the transmission shifts abnormally, slips, or enters limp mode, because the system may not be able to verify auxiliary pump operation. If the vehicle drives normally, limit use and have the feedback fault diagnosed promptly.
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.