Transmission

P0758 — Shift Solenoid C Circuit Electrical Fault

Severity: medium Drive with care, to a shop

What P0758 means

The transmission control module (TCM) drives shift solenoids that open and close fluid passages in the valve body to apply and release gears. On P0758 the TCM sees a voltage or current in the solenoid C circuit that doesn't match what it expects, such as an open circuit or a short to ground or power. Which gears depend on solenoid C varies by transmission.

Symptoms

  • Check engine light on
  • Harsh or banging shifts
  • Missed or delayed shifts
  • Slipping between gears
  • Transmission limp mode
  • Stuck in one gear

Possible causes

  1. Failed shift solenoid C (open or shorted coil)
  2. Dirty or burnt transmission fluid clogging the solenoid
  3. Valve body wear or debris in passages
  4. Damaged, corroded or oil-soaked wiring or connector at the transmission
  5. Fluid wicking into the harness connector
  6. Faulty driver circuit inside the TCM

How to diagnose

  1. Scan for all codes and freeze frame data, noting any other transmission codes
  2. Check fluid level and condition: color, smell, debris
  3. Inspect the transmission connector and harness for corrosion, oil and chafing
  4. Measure solenoid C resistance and compare with the manufacturer spec
  5. Test the wiring from the TCM to the solenoid for opens and shorts to ground or power
  6. Check battery and supply voltage to rule out low voltage
  7. Drop the pan and inspect the magnet and filter for metal debris
  8. If wiring tests good, evaluate the TCM driver

Common fixes

  • Replace shift solenoid C
  • Change transmission fluid and filter
  • Repair wiring or replace the transmission connector or harness
  • Clean or replace the valve body
  • Repair or replace the TCM if confirmed faulty

Questions and answers

What does P0758 mean?

It indicates an electrical fault in the shift solenoid C circuit, usually an open or short. The transmission may shift harshly or go into limp mode.

Can I drive with P0758?

Only briefly and gently, for example to a shop. Driving with slipping or harsh shifts can damage the clutches and valve body.

Will replacing the solenoid fix it?

Not always. Check the fluid, wiring and connector first, since dirty fluid or a damaged harness can ruin a new solenoid too.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.