P0948: Hydraulic Pump Relay/Control Circuit High

What it means

The hydraulic pump relay/control circuit reports a circuit high 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. P0948 sets when the monitored circuit signal is higher than expected, which may happen if the control wire is shorted to battery power, the relay coil is open, or a connection has excessive resistance.

Common causes

Most likely first.

1. Control wire shorted to B+
2. Open 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. Save freeze-frame data and review related relay or pump codes to see when the high signal was detected.
2. Inspect the relay, socket, and harness connectors for corrosion, loose terminals, or damaged wiring that could affect the circuit.
3. Check the control wire for contact with a battery-positive feed or pinched insulation along its route.
4. Test the relay coil and control circuit for an open or short to power, following the manufacturer's wiring information and specification.
5. If the relay and wiring pass, check the module connector and control output for an abnormal signal.

Common fixes

• Repair a loose or corroded relay or harness connection.
• Repair control wiring shorted to battery power.
• Replace a relay with an open coil.
• Repair the module connection or control output if circuit testing identifies it as the source.

Can I keep driving?

Avoid driving if shifts are delayed, harsh, or slipping, since the pump may not respond correctly and limp mode may follow. Stop if the transmission loses drive or cannot shift predictably.