Powertrain, generic · Transmission

P097C Shift Solenoid C Control Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

Open-circuit fault in the drive circuit of shift solenoid C. GM documents it for the Allison 1000 six-speed in its 2022 to 2025 heavy-duty tables as Shift Solenoid 3 Control Circuit Open, with the same intrusive low-side test as SS1 and SS2: three samples, 120 ms, battery 9 to 18 V, MIL after one trip. It is the youngest of three codes for this one fault on that gearbox: 2007 used P0978, only outside reverse trim, 5th and 6th gear, 2016 merged it into P0979 with a 200 kOhm limit. Ford reports an open SSC under P0760, and no other maker was found using P097C. A related pressure switch code may set too, because SS3 strokes the S3 valve that switch PS3 watches.

Likely causes

Open coil of shift solenoid 3/C
Loose, wet or corroded pin in the transmission connector
Broken wire between module and solenoid C
Faulty low-side driver in the control module

Symptoms

  • MIL on after one faulty trip
  • Upper gears unavailable or fixed default gear
  • Possible additional pressure switch code

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–1,500
Time1–5 h

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

Parts involved

shift solenoid cwiring harnesstcm

Related codes

P0978P0979P0980P0760P097BP0872

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