P0764 – Shift Solenoid “C” Intermittent

System: Powertrain | Standard: ISO/SAE Controlled | Fault type: General | Location: Designator C

Definition source: SAE J2012/J2012DA (industry standard)

DTC P0764 indicates the powertrain control system detected an intermittent condition involving Shift Solenoid “C.” “Intermittent” means the fault is not consistently present; the signal or commanded/observed behavior drops in and out, often depending on temperature, vibration, harness movement, or operating state. Because transmission designs, solenoid naming conventions, and monitoring strategies vary by vehicle, the exact solenoid location, access method, and the enable conditions for the monitor can differ. Use the correct service information for connector views, pinouts, test points, and acceptance criteria, and verify whether the code set as current, pending, or history before replacing any parts.

What Does P0764 Mean?

P0764 – Shift Solenoid “C” Intermittent means the control module detected an intermittent fault related to the shift solenoid identified as “C.” Based on the official definition, the issue is not necessarily a constant electrical open/short; rather, the module is seeing the solenoid circuit or solenoid response behave inconsistently over time. SAE J2012 defines the standardized structure for DTCs, but the practical interpretation (what “C” corresponds to, how the module verifies solenoid operation, and what operating conditions must be met to run the test) varies by vehicle. Proper diagnosis focuses on confirming the intermittent condition with repeatable testing and data capture.

Quick Reference

• Subsystem: Automatic transmission shift control; Shift Solenoid “C” control/feedback path (as named by the vehicle’s service information).
• Common triggers: Intermittent harness/connector contact, unstable power/ground to the solenoid or transmission connector, solenoid internal intermittency, or control-module detection of inconsistent solenoid performance.
• Likely root-cause buckets: Wiring/connector issues, solenoid/actuator fault, power/ground integrity, fluid intrusion at connectors, or (less commonly) module/driver concerns.
• Severity: Often moderate; may cause harsh/incorrect shifts or limited shifting strategy depending on how the transmission fails safe.
• First checks: Scan tool freeze-frame review, clear-and-retest, connector inspection at transmission and module, harness wiggle test, and live-data monitoring for solenoid command/state irregularities.
• Common mistakes: Replacing the solenoid without confirming an intermittent electrical/contact issue or without capturing data showing when the fault occurs.

Theory of Operation

Shift solenoids are electrically controlled valves that help route hydraulic pressure to select gears. The control module commands each solenoid (often with on/off or duty-cycle control), expecting a predictable change in hydraulic circuit behavior that results in a specific gear ratio or shift event. To confirm proper operation, the module may monitor the solenoid control circuit’s electrical behavior and compare the commanded state to inferred transmission response using inputs such as turbine/engine speed and output speed.

An intermittent fault is set when the module detects that the solenoid “C” circuit or expected response becomes inconsistent—working normally at times and then deviating. Common reasons include momentary loss of continuity, connector pin fit issues, vibration-related opens, internal solenoid coil intermittency, or unstable power/ground. The monitor’s exact logic and when it runs vary by vehicle, so service information is essential.

Symptoms

• Harsh shifting: Abrupt or jolting shifts that come and go.
• Shift flare: Engine speed rises briefly between shifts intermittently.
• Wrong gear: Occasional gear selection that doesn’t match driver demand.
• Delayed engagement: Intermittent delay when shifting into drive or reverse.
• Limp strategy: Periodic reduced shifting capability or fixed-gear operation.
• Warning lamp: Check engine light may be intermittent or return after clearing.
• Reduced performance: Sporadic loss of acceleration due to abnormal shift scheduling.

Common Causes

• Intermittent wiring fault in the shift solenoid “C” control circuit (chafing, pinched harness, broken conductor inside insulation)
• Poor connector contact at the solenoid, internal harness, or transmission/PCM interface (loose fit, corrosion, moisture intrusion, terminal fretting)
• Shift solenoid “C” coil or internal solenoid fault that occurs only under certain conditions (heat-related intermittency)
• Intermittent loss of power feed or ground for the transmission solenoid circuits (shared fuse, splice, ground point with high resistance)
• Valve body or internal transmission harness issue causing inconsistent solenoid actuation or feedback (varies by vehicle design)
• Transmission fluid contamination or debris contributing to erratic solenoid movement (does not prove failure without testing)
• Control module driver/command issue or software-related anomaly affecting solenoid “C” command intermittently (less common; confirm with tests)
• Aftermarket electrical modifications or recent repair work leading to disturbed connectors, incorrect routing, or damaged insulation

Diagnosis Steps

Tools typically needed include a scan tool with live data and bidirectional controls (if supported), a digital multimeter, back-probing pins, and wiring diagrams/service information for connector pinouts. A test light may help for quick power/ground checks, and basic hand tools may be needed for access. If available, use a scope for intermittent command/response checks during a road test.

1. Confirm the DTC and capture freeze-frame data. Check for additional transmission or power supply related DTCs and address those first if they indicate a broader power/ground or communication problem.
2. Clear codes and perform a short drive or run conditions that typically set the fault while logging live data. Note whether the code returns immediately or only after heat/road vibration, which supports an intermittent electrical/contact issue.
3. Perform a visual inspection of the transmission solenoid harness routing and connectors. Look for rubbed-through insulation, crushed sections, fluid intrusion, damaged locks, or signs the harness has contacted hot/exhaust or moving components.
4. With the key off, disconnect relevant connectors (varies by vehicle) and inspect terminals for spread pins, corrosion, moisture, or partial seating. Correct any mechanical fit issues before electrical measurements.
5. Verify power feed and ground integrity for the solenoid circuit using service information. Check for intermittent supply by monitoring the feed under load (where applicable) rather than only checking continuity.
6. Perform voltage-drop testing on the power and ground paths while the circuit is commanded on (or under an equivalent loaded test method per service information). Excessive voltage drop indicates high resistance at a connector, splice, fuse contact, or ground point.
7. Check the shift solenoid “C” coil and circuit for opens/shorts per service information. Measure resistance at the component and again from the control-module-side connector to compare; a difference points to harness/connector issues between the two points.
8. Use bidirectional controls (if available) to command shift solenoid “C” on/off while observing live data and listening/feeling for consistent actuation (access varies by vehicle). If the command is stable but response is inconsistent, focus on the solenoid, internal harness, or hydraulic/mechanical factors.
9. Conduct an intermittent fault “wiggle test” while monitoring the solenoid command/status and electrical readings. Gently manipulate harness sections, connectors, and known stress points; if the fault appears/disappears, isolate the exact location and inspect for broken strands or terminal fretting.
10. If electrical tests pass but the issue persists, evaluate internal transmission harness/valve body related concerns as applicable (varies by vehicle). Confirm connector sealing and fluid contamination; consider further diagnosis for module driver issues only after the circuit and component are proven good.

Professional tip: Intermittent solenoid DTCs are often caused by high resistance at terminals rather than a fully failed solenoid. Prioritize loaded testing (voltage drop) and repeat measurements hot vs. cold. If the fault is vibration-related, secure the harness in its normal position during testing and reproduce the exact conditions that trigger the code to avoid false “no fault found” results.

Possible Fixes & Repair Costs

Repair costs for P0764 vary widely because the root cause can range from a simple connector issue to an internal transmission/valve body problem. Total cost depends on confirming the fault with testing, parts replaced, labor time, and accessibility of the shift solenoid “C” circuit.

• Repair wiring/connector issues: Clean corrosion, reseat connectors, correct poor pin fit, repair damaged insulation, and secure harness routing that may intermittently open/short.
• Restore power and ground integrity: Repair shared feeds/grounds for the transmission solenoids, address loose ground points, and correct high-resistance connections found with voltage-drop testing.
• Replace shift solenoid “C”: Replace only after verifying the solenoid intermittently fails electrically or mechanically (as supported by scan data and commanded tests, if available).
• Service valve body/solenoid pack (varies by vehicle): If the solenoid is integrated or the hydraulic control assembly is implicated by repeatable tests, service/replace the assembly per service information.
• Address fluid condition issues: Correct low/incorrect/contaminated fluid only if verified; poor fluid condition can contribute to erratic shift behavior that complicates diagnosis.
• TCM/PCM connector and terminal repair: Repair backed-out terminals or intermittent module-connector contact, especially if wiggle testing changes solenoid status/command feedback.
• Module update or replacement (only if proven): Reflash or replace the control module only after power/ground, wiring, and solenoid checks confirm the module is the remaining verified cause.

Can I Still Drive With P0764?

You may be able to drive cautiously for a short distance if the vehicle shifts normally and no additional warnings are present, but P0764 can cause unpredictable shifting. Avoid hard acceleration, towing, and high-speed merging. If you notice harsh shifts, slipping, loss of propulsion, a sudden change in available gears, or any safety-related warnings (reduced power, brake or steering concerns), do not continue driving—have the vehicle inspected and repaired.

What Happens If You Ignore P0764?

Ignoring P0764 can lead to worsening shift quality, increased heat and wear inside the transmission, and intermittent loss of expected gear operation. Continued driving with erratic shifting can accelerate damage to friction elements and hydraulic components, potentially turning an intermittent electrical/control issue into a more extensive repair.

Related Solenoid Shift Codes

Compare nearby solenoid shift trouble codes with similar definitions, fault patterns, and diagnostic paths.

• P0759 – Shift Solenoid “B” Intermittent
• P0754 – Shift Solenoid “A” Intermittent
• P0774 – Shift Solenoid “E” Intermittent
• P0769 – Shift Solenoid “D” Intermittent
• P0789 – Shift/Timing Solenoid Intermittent
• P0765 – Shift Solenoid “D”

Key Takeaways

• P0764 indicates intermittency: The fault is intermittent behavior in the shift solenoid “C” circuit/operation, not a guaranteed failed part.
• Start with basics: Intermittent wiring, connector pin fit, and shared power/ground problems are common and should be tested first.
• Use data and repeatability: Live-data logging and wiggle testing are important to catch the fault as it occurs.
• Verify before replacing parts: Replace the solenoid or valve body only when testing supports that conclusion.
• Driving risk is variable: Some vehicles may enter a default strategy that changes shifting and can affect safety in traffic.

Vehicles Commonly Affected by P0764

• Vehicles with electronically controlled automatic transmissions using multiple on/off or variable-force shift solenoids
• Vehicles where shift solenoids are internal to the transmission and share a common internal harness
• High-mileage vehicles with heat-cycled connectors and harnesses near the transmission case
• Vehicles operated in stop-and-go conditions where frequent shifts increase solenoid duty cycles
• Vehicles used for towing or heavy loads that increase transmission temperatures and stress electrical connections
• Vehicles in wet/corrosive environments where external connectors are more prone to moisture intrusion
• Vehicles with prior transmission or engine work where harness routing/retention may be disturbed
• Vehicles with underbody impact exposure that can pinch or chafe transmission wiring

FAQ

Does P0764 mean shift solenoid “C” is bad?

No. P0764 means the control module detected intermittent behavior related to shift solenoid “C.” The solenoid could be the cause, but intermittent wiring/connector contact, shared power/ground issues, or internal harness/valve body concerns can produce the same DTC. Testing is required to confirm the root cause.

What’s the difference between an intermittent code and a circuit open/high/low code?

An intermittent code indicates the fault appears and disappears, often due to vibration, temperature changes, or marginal electrical contact. Circuit open/high/low codes point to more consistently detected electrical conditions. With P0764, focus on conditions that come and go, and use wiggle testing and longer live-data logs.

Will clearing P0764 fix the problem?

Clearing the code only resets stored fault information; it does not correct the underlying intermittent condition. If the cause remains, the DTC can return once the monitor runs again or once the intermittent connection/behavior reoccurs during driving.

What checks are most important before replacing parts?

Prioritize connector and harness inspection for rubbing, fluid intrusion, and poor terminal tension; verify power and ground integrity with voltage-drop testing under load; and review scan data to see when the fault occurs. If available, use bi-directional controls to command the solenoid and compare commanded states to observed response.

Can low or degraded transmission fluid cause P0764?

Fluid issues typically affect shift performance, and they can contribute to erratic shifting that complicates diagnosis, but P0764 is specifically an intermittency fault associated with shift solenoid “C.” Check fluid condition and level only as part of a broader diagnostic process, and confirm any electrical intermittency with targeted testing.

Confirm the repair by repeating the conditions that previously triggered the intermittent event and by reviewing a post-repair live-data log to ensure shift solenoid “C” operation remains stable without the DTC returning.