Powertrain, generic · Transmission

P0788 Shift Timing Solenoid A High

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

'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). P0788 means the circuit is shorted to positive or draws overcurrent. GM's 4L60-E checks the 3-2 downshift solenoid output for an invalid state at more than 43 of 50 counts; GM's Aisin-type five-speed flags SLS current above 1356 mA for 2 s and lights the MIL at once. Limp mode and shift jolts follow; the opposite is P0787.

Likely causes

Short to positive in the harness
Winding short in the solenoid
Module driver stage

Symptoms

  • Warning lamp
  • Limp mode
  • Shift jolts

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€100–800
Time1–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

shift timing solenoidtransmission wiringtransmission control module

Related codes

P0785P0787P0786P078D

References: gsi.ext.gm.com, gsi.ext.gm.com.