Cause
Failed shift timing solenoid
The solenoid controlling the rate at which a shift is completed rather than which gear is selected, so its failure changes how a change feels instead of preventing it. That is the distinction worth holding: a shift solenoid decides where the transmission goes, and a shift timing solenoid decides how quickly it gets there. Confusing the two sends a diagnosis to the wrong valve.
The complaint is therefore about quality, not function. Too fast and the change is a mechanical thump that the driver feels through the seat; too slow and the clutch packs slip against each other for longer than they were designed to, generating heat and wearing the friction material every time. The slow case is the damaging one and the one drivers tolerate, because a soft change feels like nothing much is wrong.
Its codes follow the standard circuit pattern and should be read that way. Low, high and open name the winding and the harness and are settled with a meter at the connector. Range and performance codes mean the circuit is electrically sound while the hydraulic response is not — a valve sticking in its bore, a blocked feed, or fluid too degraded to control. An intermittent code that appears only when the transmission is hot is nearly always the hydraulic case, since clearances and fluid viscosity both move with temperature.
Typically a moderate job.
Codes this can cause (5)
Codes where this is a likely explanation first, rather than merely a possible one.
- P0785 Shift Timing Solenoid A Likely for this code High
- P0786 Shift Timing Solenoid A Range/Performance Likely for this code High
- P0787 Shift Timing Solenoid A Low Likely for this code High
- P0788 Shift Timing Solenoid A High Likely for this code High
- P0789 Shift Timing Solenoid A Intermittent Likely for this code High
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Others who found this
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
Sign in or create an account to add what you found about Failed shift timing solenoid.