VW T5 split charge fault fixed by replacing melted midi fuse

The Problem

The split charge relay on a 2014 VW T5 with a Redarc BCDC1240D battery-to-battery charger was not working, and an OBD scan showed a generator communication fault (code 02252). The owner had tested voltage drop along the main cable with a multimeter and found no significant loss, so the connections appeared good.

Note: a split charge fault often surfaces as fault code 02252 (generator communication fault) because the BCDC1240D draws its charge feed from the same alternator/D+ ignition circuit the vehicle uses to monitor the generator. When that feed is interrupted by a failed fuse or high-resistance joint, the control module sees the loss of expected current/communication on that circuit and logs it as a generator comms fault rather than pointing directly at the split charge wiring — so if you pull the same code, check the split charge fuse and feed before condemning the alternator.

Solution

1. Remove the cover from the midi fuse holder in the split charge wiring and visually inspect the fuse and holder body.
   • Look for melted plastic, the two fuse-link bolts having shifted apart, and a broken rather than cleanly blown fuse link.
2. Inspect the short length of cable between the fuse holder and the Anderson connector for burnt or blackened insulation.
   • A poor crimp at the fuse end creates high resistance that generates heat over time rather than a sudden overcurrent that would blow the fuse cleanly.
3. Replace the failed midi fuse holder with a strip fuse rated to match your charger's maximum output current. The BCDC1240D is a 40 A charger, so fit a 50 A strip fuse — this sits comfortably above the charger's continuous 40 A draw while still protecting the cable.
4. Replace the short cable if insulation is damaged, and re-crimp any suspect terminal ends to ensure a low-resistance connection.