Powertrain, generic · Hybrid propulsion

P0C2B Electric/Auxiliary Transmission Fluid Pump Control Module Feedback Signal

Check engine lightOn

EmissionsRelevant

Drive cycleRequired

Limp modeNo

P0C2B concerns the status signal the auxiliary pump control module sends back to the controlling module. GM uses it on the Two-Mode hybrid trucks and SUVs (Tahoe, Yukon, Escalade, Silverado, Sierra, 2ML70): the hybrid controller expects a complete fault status message from the pump controller every 1.5 s; if it is missing or incomplete for 9.75 s with the vehicle in Run or Crank, the code sets as Type B, MIL after two trips. GM preliminary information PIP4751G stresses that P0C2B, with or without P2797, rarely means a bad pump: check the wiring, replace the pump control module if its date code is 089-11 or older, and note that a key held in Crank during a no-start can set it. P0C2C to P0C2E are the specific variants.

Likely causes

Wiring or terminal tension fault between hybrid controller and pump control module

Early pump control module (GM date code 089-11 or older)

Key held in crank for a long time during a no-start

Symptoms

MIL after two drive cycles
Bumps, lulls or surges around auto-stops

Repair estimate

DifficultyMediumWorkshop job

Parts and labour€50–1,200

Time0.5–3 h

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

Parts involved

aux trans pump control modulewiring harnesstcm

Related codes

P0C2C P0C2D P0C2E P2797 P0C23

References: gsi.ext.gm.com, gsi.ext.gm.com, static.nhtsa.gov.