P0764

Code

Generic P — Powertrain

Shift Solenoid C Intermittent

Brand: Generic

Type: P — Powertrain

Views: UK: 20 EN: 46 RU: 29

AI status

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Page language: EN

Causes

Intermittent open or short in solenoid C wiring or connector
Corroded or loose connector pins at the solenoid or TCM
Failing shift solenoid C (internal intermittent)
Contaminated or low/overfilled transmission fluid causing solenoid sticking
Intermittent TCM/PCM driver fault
Blown fuse, poor power supply or poor ground to transmission control circuits

Symptoms

Check Engine Light / Transmission MIL illuminated
Erratic, delayed, harsh or incorrect gear changes
Transmission may go into limp-in mode or be stuck in a single gear
Intermittent loss of drive or unexpected gear hunting
Fault may clear temporarily and then return (intermittent behavior)

What to check

Read freeze-frame data and scan for additional transmission / communication codes
Check transmission fluid level and condition (metallic particles, burnt smell)
Visually inspect solenoid C connector, wiring harness and TCM connector for damage or corrosion
Backprobe solenoid C connector while commanded ON/OFF and observe voltage and ground
Measure solenoid coil resistance (with harness disconnected) and compare to spec
Wiggle test wiring/connectors while monitoring live data to reproduce intermittent fault

Signal parameters

Solenoid C coil resistance: typically vehicle-specific (commonly ~6–30 Ω) — check OEM spec
Solenoid supply voltage: battery voltage (~11–14 V) when commanded ON or if driven high-side
Ground continuity: low milliohms to chassis ground for return path
PWM duty cycle (if solenoid is PWM-controlled): 0–100% depending on commanded pressure
Current draw: varies by design (typically under a few amps) — compare to spec
TCM command status: ON/OFF or duty percentage in live data

Diagnostic algorithm

Retrieve and record all transmission and powertrain codes and freeze-frame data. Note whether P0764 is the only code or accompanied by others (P0700, other solenoid codes).
Check transmission fluid level/condition. If fluid is contaminated or burnt, consider fluid/filter service before further tests.
Visually inspect wiring and connectors from the TCM to the transmission solenoid pack. Repair any chafing, exposed wire, or damaged terminals.
With ignition ON (engine off) or engine running as OEM directs, backprobe the solenoid C connector. Command the solenoid ON via a scan tool while watching voltage/current and live status. Note intermittent loss of signal when wiggle-testing the harness.
Measure coil resistance with the harness unplugged. Compare to OEM spec. Significant deviation or open circuit indicates a bad solenoid.
If resistance is OK but operation is intermittent, use a lab scope to inspect the drive waveform from the TCM for missing pulses, noise or voltage spikes. Check for intermittent ground or power supply.
Repair wiring/connectors as required (clean/replace terminals, solder/heat-shrink or replace harness sections). Clear codes and retest on the road to attempt to reproduce the intermittent.
If wiring and connectors are good but intermittent persists and solenoid coil shows intermittent continuity under stress/wiggle, replace the solenoid/solenoid pack or valve body as appropriate.
If after solenoid and harness replacement the fault remains, suspect TCM/PCM driver failure and evaluate TCM grounds/power and consider TCM bench testing or replacement per OEM procedures.
After repair, confirm no return of code by performing a full drive cycle and rechecking for stored or pending codes.

Likely causes

Damaged or chafed harness to the shift solenoid (pin break or intermittent short when moved)
Corroded connector or bent terminal at the transmission solenoid pack
Failing solenoid that works intermittently (intermittent coil connection)
Poor ground or weakened power feed to the solenoid driver
Contaminated or degraded transmission fluid allowing the solenoid/valve to stick
Intermittent TCM output stage (less common)

Fault status

⚠️ Status

Intermittent fault detected in Shift Solenoid C circuit — sporadic open/short or intermittent solenoid operation detected by transmission control module. Can cause erratic shifting or limp mode.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1-4 hours