What Does P0766 Mean?
Shift Solenoid D is performing outside its expected parameters or is stuck in the off position. The TCM commands solenoid D to apply but detects that the expected gear ratio change is not occurring. This generally affects higher gear shifts (such as 4th gear) and can cause the transmission to remain in a lower gear, slip, or produce harsh shift events.
Common Causes
35%
Shift solenoid D stuck closed due to contamination or internal failure
25%
Valve body wear in the solenoid D shift valve bore
20%
Degraded or contaminated transmission fluid affecting solenoid D operation
15%
Internal clutch pack or band wear for the gear controlled by solenoid D
5%
Wiring issue reducing current flow to solenoid D
Diagnostic Steps
1
Monitor commanded vs. actual gear ratio in live data to confirm solenoid D is being commanded but not achieving the expected shift.
2
Check transmission fluid level and quality — service the fluid if it is dark, burnt, or contaminated.
3
Measure solenoid D resistance at the transmission connector and compare to specification.
4
Command solenoid D on/off with a bi-directional scan tool and verify proper operation.
5
Perform a line pressure test to determine if the hydraulic circuit has adequate pressure.
6
If solenoid and wiring check out, the valve body or clutch pack may need further inspection.
Estimated Repair Cost
$250 - $1,400
Parts + labor, varies by vehicle and location
Shift Solenoid D is performing outside its expected parameters or is stuck in the off position. The TCM commands solenoid D to apply but detects that the expected gear ratio change is not occurring. This generally affects higher gear shifts (such as 4th gear) and can cause the transmission to remain...
The most common cause of P0766 (Shift Solenoid D Performance or Stuck Off) is: Shift solenoid D stuck closed due to contamination or internal failure
Typical repair costs for P0766 range from $250 to $1,400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The transmission may not engage higher gears, resulting in higher RPMs during driving. Low-speed urban driving is possible, but highway driving may be unsafe if the transmission cannot upshift. Repair promptly.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0766 to identify the root cause.
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Quick Info
Category
Powertrain
System
Automatic Transmission
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
