P0947: Hydraulic Pump Relay/Control Circuit Low

What it means

The hydraulic pump relay/control circuit reports a circuit low condition. Pump cannot be commanded reliably.

At a glance

• Usually lights the check-engine light
• The engine or gearbox may go into limp mode

How it works

The hydraulic pump relay control circuit carries the TCM's command to the pump relay. P0947 sets when the monitored circuit signal is lower than expected, which can result from a short to ground, a shorted relay coil, or a poor corroded connection.

Common causes

Most likely first.

1. Control wire shorted to ground
2. Internal short in coil
3. Connector pins corroded - high contact resistance

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 check related relay or pump codes to see whether the low signal occurs during a pump command.
2. Inspect relay and harness connectors for corrosion, moisture, loose pins, or damaged insulation that could create a short to ground.
3. Trace the control wire for contact with grounded metal or pinched sections, especially near connector bends and harness supports.
4. Test the relay coil and control circuit for a short to ground, using the manufacturer's wiring information and specification.
5. If the relay and wiring are sound, verify the module's control output and connector before diagnosing a module fault.

Common fixes

• Clean or repair corroded connector pins and restore a sound connection.
• Repair control wiring shorted to ground or damaged insulation.
• Replace a relay with a shorted coil.
• Repair a faulty module connector or control output if testing confirms it.

Can I keep driving?

Avoid driving if shifting is abnormal or the transmission enters limp mode, because the pump may not operate reliably. Stop if the vehicle slips, shudders severely, or loses drive.