What P0785 means
'Shift timing solenoid' means different parts: on GM's 4L60-E the 3-2 downshift solenoid that times the band apply on that downshift, on Aisin five-speeds (GM, Saab) the linear valve SLS that sets clutch pressure during the shift, and on the 2017–18 Genesis G80/G90 with shift-by-wire the on/off solenoids that engage drive (A) and reverse (B).
How the engine computer detects it
P0785 is the general circuit code for solenoid A. GM's 2006 tables use it for the 3-2 downshift solenoid circuit (more than 43 of 50 failed counts, after one trip); Saab's 2002 Aisin box for an open or short in the SLS circuit with warning lamp and limp mode; Hyundai's Genesis bulletins for the drive solenoid, replacing valve and electronic module and then the module if it returns. Limp mode, harsh 3-2 downshifts or – on the Genesis – no drive follow.
Written from public technical sources and not yet checked by a mechanic. How we write these pages
Symptoms
- Warning lamp
- Limp mode
- Harsh 3-2 downshift (GM) or rough shifts (Aisin)
- Genesis shift-by-wire: drive cannot be engaged
Common causes
- Solenoid coil open or shorted Most likely
- Connector or wire at the transmission (oil, corrosion) Possible
- Electronic module or transmission module driver Possible
How to diagnose P0785
- Read every stored code with an OBD-II scanner. If misfire or fuel trim codes are there too, fix those first: they often cause this one.
- Inspect the parts involved: shift timing solenoid, transmission wiring, transmission control module.
- Work through the causes above from most to least likely, cheapest checks first.
- Clear the code and drive a full drive cycle to confirm the repair held.
Vehicles that report P0785 most
| Vehicle | Years | Reports | Share | Median miles |
|---|---|---|---|---|
| Chevrolet Blazer | 1997–2000 | 3 | — |
Counts of owner complaints to the NHTSA that mention P0785 (6 in total), not failure rates: popular models get more complaints simply because more of them are on the road. Models with fewer than 3 complaints are left out.
Reading the code
- P
- Powertrain
- 0
- Generic (SAE) code
- 7
- Transmission
- 85
- Specific fault
Questions drivers ask
Can I drive with code P0785?
If the car shifts normally, drive gently to a shop. If it's stuck in one gear, slips, shifts harshly or won't move out of Park, don't drive it: have it towed.
Will my car pass an emissions inspection with P0785?
Probably not in states that test vehicles with an OBD-II scan: an emissions-related code that keeps the check engine light on is usually an automatic fail. Rules differ by state and county, so check yours.
Often reported together
Codes that owners mention in the same NHTSA complaints as P0785. They can point to a shared cause, so it's worth checking them together.
This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.