P0785 on 2000-2007 GMC Sierra 1500 — Shift/Timing Solenoid "A" Malfunction
1 vehicles · 1 makes · $1,800-$3,500 repair
Most Reported On
P0785 is an OBD-II diagnostic trouble code meaning “Shift/Timing Solenoid "A" Malfunction.” This code indicates a malfunction in the shift/timing solenoid circuit, often associated with a solenoid (such as the 3-2 timing/downshift solenoid) that controls the timing and feel of gear changes. The transmission control module detected the solenoid is not performing as commanded electrically or hydraulically. Symptoms may include harsh or poorly timed shifts, particularly on downshifts, or a check engine light with otherwise normal driving. It generally indicates a transmission shift-control fault. This code is most commonly reported on 2000-2007 GMC Sierra 1500, with repair costs ranging from $1,800 to $3,500.
Common Causes
Typical Repair Cost
Based on 1 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
To diagnose P0785, you'll need an OBD-II scanner. Here are our recommendations at every price point.
ANCEL AD310 Classic OBD-II Scanner
by ANCEL
A simple, affordable code reader that reads and clears check engine codes. Great for quick diagnostics on any OBD-II vehicle (1996+).
- Read & clear engine codes
- View freeze frame data
- I/M readiness status
- No batteries or app needed
BlueDriver Pro Bluetooth Scanner
by BlueDriver
Bluetooth OBD-II scanner with a free companion app. Provides enhanced diagnostics, smog readiness, and repair reports sourced from a database of verified fixes.
- Enhanced diagnostics (ABS, SRS, transmission)
- Repair Reports with verified fixes
- Smog check readiness
- Free app (iOS & Android)
LAUNCH CRP123X OBD-II Scanner
by LAUNCH
A professional-grade handheld scanner that reads all four major systems (engine, transmission, ABS, SRS) with live data streaming and graphing.
- Engine, transmission, ABS, SRS diagnostics
- Live data stream & graphing
- AutoVIN for vehicle identification
- Free lifetime updates via Wi-Fi
Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level diagnostic tablet with bi-directional control, active tests, and full system coverage. Ideal for serious DIYers and small shops.
- All-system diagnostics (25+ modules)
- Bi-directional control & active tests
- Oil reset, EPB, BMS, TPMS, injector coding
- 7-inch touchscreen with Android OS
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FAQ
What does P0785 mean?
P0785 stands for "Shift/Timing Solenoid "A" Malfunction." This code indicates a malfunction in the shift/timing solenoid circuit, often associated with a solenoid (such as the 3-2 timing/downshift solenoid) that controls the timing and feel of gear changes. The transmission control module detected the solenoid is not performing as commanded electrically or hydraulically. Symptoms may include harsh or poorly timed shifts, particularly on downshifts, or a check engine light with otherwise normal driving. It generally indicates a transmission shift-control fault.
What are the most common causes of P0785?
The most common causes of P0785 are: Faulty shift/timing solenoid, Low or contaminated transmission fluid, Wiring or connector damage in the solenoid circuit, Valve body debris or wear, Internal hydraulic leaks, Dirty transmission filter affecting solenoid response, Faulty transmission control module (less common). The specific cause varies by vehicle.
How much does it cost to fix P0785?
Repair costs for P0785 range from $1,800 to $3,500, depending on the vehicle and root cause.
Which vehicles are affected by P0785?
Au7o has documented P0785 across 1 vehicle models from 1 manufacturers: GMC.
Sources (5)
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.