P2C44: PowerBoost ground integrity before auxiliary battery isolator replacement

P2C44:00 on a 2021–2022 F-150 PowerBoost can lead to diagnosis of the auxiliary battery isolator, but Ford SSM 50843 puts several checks before that replacement. The described complaint is a wrench indicator with P2C44:00 or U061E:00 stored in the powertrain control module.

The ground path is part of the system

Ford identifies ground circuit GD132 as one possible source and specifically includes G102, C146 and C1989C in the integrity investigation. These references identify areas within the vehicle’s proper diagnostic procedure; they are not a universal set of terminals to probe on every F-150.

A poor ground path and a defective isolator can produce related symptoms but require different repairs. The bulletin therefore calls for the relevant pinpoint test and careful circuit inspection before deciding that the isolator itself is responsible. Finding a code with “isolation” wording is not equivalent to finding a failed isolator.

The auxiliary battery has a separate decision role

After the circuit checks, Ford requires the auxiliary battery condition test. Isolator replacement is the stated next step only when the initial pinpoint test finds no issue, the ground integrity checks are satisfactory and the auxiliary battery passes. A battery that fails that evaluation does not satisfy the bulletin’s replacement branch.

Bring the complete scan and any recent battery or wiring service history. Ask the workshop to document the ground and battery results that support its conclusion. The source provides a clear sequence for the specified PowerBoost configuration, but no stand-alone resistance limit, universal battery specification or owner-level bypass procedure.

Source and applicability

Ford SSM 50843: 2021–2022 F-150 with the 3.5L PowerBoost engine, wrench indicator and P2C44:00 and/or U061E:00 in the PCM.

SSM 50843 — NHTSA manufacturer communication 10214160, physical PDF page 1.