P0785: Shift Timing Solenoid A

What does P0785 mean?

'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). 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.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Warning lamp
• Limp mode
• Harsh 3-2 downshift (GM) or rough shifts (Aisin)
• Genesis shift-by-wire: drive cannot be engaged

Common causes

• High Solenoid coil open or shorted
• Medium Connector or wire at the transmission (oil, corrosion)
• Medium Electronic module or transmission module driver

Likelihood is a general estimate across vehicles; your make and model may differ.