P0798: Pressure Control Solenoid C Electrical

What it means

The TCM detects an electrical fault in the pressure control solenoid C circuit, such as open winding, short to ground or short to power.

At a glance

• Usually lights the check-engine light

How it works

Pressure control solenoid C is an electrically controlled valve that regulates transmission hydraulic pressure. P0798 sets when the TCM detects an electrical fault in the solenoid C circuit, such as an open coil or wiring short, rather than simply an incorrect hydraulic response.

Common causes

Most likely first.

1. Solenoid coil open
2. Wiring shorted

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. Use freeze-frame data and live transmission data to note when the fault occurred and whether solenoid C operation or related transmission behavior changed.
2. Inspect the solenoid C connector and harness for disconnected plugs, corrosion, fluid intrusion, damaged insulation, or contact with other wiring.
3. Use the wiring diagram to check the solenoid C circuit for opens or shorts to ground or power, following the manufacturer's procedure.
4. Test the solenoid C coil and compare the result with the manufacturer's specification.
5. If the coil and harness pass, check the TCM connector and circuit controls for poor terminal contact or a control-side fault.

Common fixes

• Reconnect or repair a loose solenoid C connector.
• Repair wiring that is open or shorted to ground or power.
• Replace pressure control solenoid C if its coil fails testing.
• Repair poor terminal contact in the transmission or TCM connector if confirmed.

Can I keep driving?

Avoid towing and hard acceleration if shifts are harsh, delayed, or slipping, since the transmission may use a limited operating strategy and continued slip can cause damage. Stop driving if gear engagement becomes unreliable.