Powertrain, generic (extended)

P2796 Electric/Auxiliary Transmission Fluid Pump A Control Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2796 points to an interrupted control line between the module and the motor of auxiliary pump A. GM's 2025 TCM tables define the test: provided the battery supplies 9 to 15 V, the controller sees more than 200 kΩ from signal to ground in at least 20 of 25 samples taken every 100 ms; the code is Type B, so the MIL comes on after two trips. On Ford's 10R60/10R80 and 8F57 automatics the pump itself reports that the PWM command signal is missing, filed as P2796_31. Ford TSB 26-2010 covers the 2022–2025 F-150 Lightning, where P2796 or P2797 in the secondary OBD modules B and C may stem from software, often first logged at 0 °C or below; reprogramming is the fix. P2798 and P2799 are the short-circuit siblings, P27A2 the same fault on pump B.

Likely causes

Broken control wire or unplugged pump connector
Poor terminal contact at the pump or module
Module software (Ford F-150 Lightning, TSB 26-2010)
Open circuit inside the pump electronics

Symptoms

  • MIL or wrench indicator on
  • Stop-start inoperative
  • Reduced performance message on electrified models

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€0–900
Time0.5–3 h

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

Parts involved

aux trans pump awiring harnesstransmission control module

Related codes

P2797P2798P2799P27A2P0C2B

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