P27CB: Pressure Control Solenoid R Electrical

What it means

The transmission control module detects an electrical fault associated with pressure control solenoid R.

At a glance

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

How it works

Pressure control solenoid R is an electrically operated valve that helps regulate transmission hydraulic pressure. The transmission control module monitors its electrical circuit and sets P27CB when it detects an electrical fault, without specifying the low, high, open, or intermittent condition.

Common causes

Most likely first.

1. Faulty solenoid coil
2. Open or short in solenoid wiring
3. Poor connector contact

Symptoms

• Transmission warning light may illuminate
• Harsh or delayed shifting
• Transmission may enter limp mode

How to diagnose it

1. Record freeze-frame data and transmission codes first to see when the solenoid R fault occurred and whether other circuit codes are present.
2. Inspect solenoid R's connector and harness for loose contacts, corrosion, damaged insulation, or wiring that could open or short.
3. Check that the connector is fully seated and its terminals make firm contact, since poor contact can interrupt the solenoid R circuit.
4. Measure solenoid R coil resistance and compare it with the manufacturer's specification to check for a faulty coil.
5. Test the solenoid R control wiring for continuity and shorts, following the vehicle wiring diagram.
6. If the wiring and coil pass, use a scan tool to compare commanded solenoid R operation with available circuit data and assess the control module circuit.

Common fixes

• Secure the solenoid R connector and clean or repair poor terminal contact.
• Repair damaged wiring in the solenoid R control circuit.
• Replace solenoid R if its coil is open, shorted, or outside the manufacturer's specification.
• Repair the control circuit if testing identifies a fault beyond the connector, wiring, or solenoid.

Can I keep driving?

Avoid towing, hard acceleration, and long trips while shifting is harsh or delayed, or limp mode is active. A pressure-control fault can worsen shifting and may lead to transmission damage; stop driving if the transmission slips badly or cannot engage gears reliably.