Powertrain, generic · Transmission

P0787 Shift Timing Solenoid A Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
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). P0787 means current or voltage in the circuit is too low – an open circuit or short to ground. GM's 4L60-E checks the 3-2 downshift solenoid output (more than 43 of 50 counts) after one trip and then sets maximum line pressure, holds third gear and disables the converter clutch; GM's Aisin-type five-speed flags SLS current below 92 mA for 12.5 s. The opposite is P0788.

Likely causes

Wire open or shorted to ground
Solenoid coil open
Module driver stage

Symptoms

  • Warning lamp
  • Limp mode (GM: fixed third gear)
  • Harsh shifts from maximum pressure

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

P0785P0788P0786P078C

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