Powertrain, generic (extended)

P2C44 Battery Isolation/Voltage Stabilization Control Circuit Performance

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

P2C44 means the isolation or voltage stabilization stage is wired and commanded, yet its behaviour does not match what the module expects. Ford is the one maker with published cases: 2021–2022 F-150 trucks with the 3.5 L PowerBoost hybrid and 10R80 MHT gearbox carry a second 12 V battery that an auxiliary battery isolator separates from the main battery. Two special service messages (SSM 50843, 50976) have the technician check ground circuit GD132 including G102, C146 and C1989C and test the auxiliary battery before swapping the isolator; bulletin 23-2031 then combined new PCM software with a new isolator (ML3Z-14526-B, up to 0.7 h). Ford shows the wrench indicator rather than the emissions lamp, sometimes together with U061E. Unlike P2C45/P2C46 the wiring voltage itself is not out of range.

Likely causes

Auxiliary battery isolator faulty (Ford replaces it per bulletin 23-2031)
Poor ground in the isolator circuit (Ford GD132, G102, C146, C1989C)
Outdated PCM software
Weak or failing auxiliary 12 V battery

Symptoms

  • Wrench (powertrain malfunction) indicator on
  • U061E may be stored alongside
  • Electrical glitches during engine pull-up

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€100–600
Time0.7–3 h

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

Parts involved

battery isolation moduleauxiliary batterywiring harnessecm

Related codes

P2C43P2C45P2C46P2C47U061EU041A

References: static.nhtsa.gov, static.nhtsa.gov, static.nhtsa.gov, patents.google.com.