P0947 Code: Hydraulic Pump Relay Circuit Low

What the P0947 code means

Automated manual transmissions (Opel Easytronic, Fiat Dualogic, Toyota MMT, BMW SMG, Ford Durashift, Volkswagen ASG) and many dual-clutch gearboxes use electric or hydraulic actuators to release the clutch, pick the gear plane (selection) and engage the gear (engagement). The transmission computer watches every actuator through position sensors. In hydraulic systems, an electric pump keeps up the accumulator pressure that operates the clutch and the shifts, and the computer turns it on through a relay.

The computer monitors the control circuit from its own driver transistor. The P0947 code means the voltage in the control circuit is low, which is either a short to ground or a missing supply. Before you change the component, check the fuse, the relay, the connector and the wiring, because those are the usual culprits.

If the pump does not run, the system loses pressure and the gearbox stops shifting. If the relay sticks closed, the pump runs nonstop and overheats. After any repair on these parts, the gearbox learning procedures (clutch touch point, selection positions and engagement positions) have to be run with a scan tool. Without them the transmission will not work properly.

To confirm it, unplug the component with the key on and watch what the reading or the code does. If the value jumps to the opposite extreme, the wiring is fine and the component is the one pulling the signal to ground. If nothing changes, look for the short in the wire, starting where the harness rubs against the engine, the chassis or the exhaust.

P0947 code symptoms

• Check engine light or another warning light on.
• Loss of hydraulic pressure.
• The gearbox will not engage gears or stays in neutral.
• Transmission or engine light on.
• Beep or warning message on the dash.

Likely causes of the P0947 code

1. Control wire shorted to ground. The component may stay on all the time, or the computer cuts the command to protect itself.
2. Interrupted supply. Blown fuse, bad relay or a cut wire.
3. Component shorted inside. Its resistance is far below the specification.
4. Connector with moisture. It creates a path to ground.

How to diagnose the P0947 code step by step

1. Command the component with the scan tool and see whether it responds.
2. Check the fuse and the relay. Measure voltage on both sides of the fuse and swap the relay with an identical one.
3. Measure the supply at the connector. You should see battery voltage with the key on, or when the component is commanded.
4. Measure the component resistance and compare it with the manual, then check the insulation to ground.
5. Check the control wire for continuity to the computer and for shorts to ground.
6. Command the actuator with the scan tool and see whether it moves.
7. Run the gearbox learning procedures after any repair.
8. Check the hydraulic fluid level and look for leaks.

How to fix the P0947 code

• Repair the connector, the wiring or the supply.
• Replace the hydraulic pump relay if it does not respond when it has the right supply and command.
• Clear the P0947 code and verify the repair.

Technical reference data

• Electric actuator (DC motor) or hydraulic solenoid valve controlled by PWM.
• Reference values only: check the manufacturer data for your vehicle.

Brand-specific notes

This is where the code is seen most. In many hydraulic systems the actuator fluid is a specific one, and the reservoir should be checked regularly.

P0947 on Opel

Very common on the Opel Easytronic.

P0947 on Fiat

Very common on the Fiat Dualogic.

P0947 on Toyota

Very common on the Toyota MMT.

P0947 on Smart

Very common on Smart cars with this style of transmission.

P0947 on BMW

Very common on the BMW SMG.

Frequently asked questions about P0947