Powertrain, generic · Transmission

P080B Upshift/Skip Shift Solenoid Control Circuit Range/Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

GM's skip-shift (CAGS) on manual gearboxes such as the T56 and TR6060 uses an engine-module solenoid that, at light load, blocks the way from 1st into 2nd so the driver shifts 1 to 4; the 1-4 lamp shows it (P0804). The engine module drives the solenoid with a low-side driver; P0803 is the open circuit. P080B would be the range or performance fault of this circuit: electrically plausible, but outside the expected range for the command – for example a coil resistance outside its window, a partial short or contact resistance. No manufacturer document available to us uses it: GM's tables from 2006 to 2019 check the solenoid only electrically (P0803 open, P080C short to ground, P080D short to positive). CARB requires a functional check of outputs where feasible. The lockout may then work unreliably.

Likely causes

Solenoid coil with shorted turns or resistance out of range
Retrofitted skip-shift eliminator with the wrong value
Corroded connector at the gearbox (contact resistance)
Control module or software

Symptoms

  • Check engine lamp (depends on manufacturer)
  • 1-4 lockout works not at all or only sometimes
  • Otherwise no change in driving

Repair estimate

DifficultyMediumDIY possible
Parts and labour€30–250
Time0.5–2 h

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

Parts involved

skip shift solenoidsolenoid wiringengine control module

Related codes

P0803P080CP080DP0804

References: law.cornell.edu, gsi.ext.gm.com, en.wikipedia.org.