Powertrain, generic · Transmission

P078B Shift Timing Solenoid B Range/Performance

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). Only Hyundai/Genesis is documented using solenoid B, and only with the base code P078A. No manufacturer document available to us uses this code; the description follows solenoid A (P0786: current deviation with the circuit intact, on GM's Aisin-type unit more than 80 mA for 2.75 s). Rough shifts and the warning lamp follow.

Likely causes

Valve or coil faulty
Connector

Symptoms

  • Warning lamp
  • Shift problems

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€150–900
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

P078AP078CP078DP0786

References: law.cornell.edu, gsi.ext.gm.com.