Some 2019-2020 Ford Ranger vehicles may exhibit random Trailer Connected/Disconnected messages in the instrument panel cluster when no trailer is connected.
This may be caused by corrosion and/or moisture in C4098 (4-pin trailer tow connector), C4099 (4/7-way trailer tow brake connector), and/or inline C405. To correct the conditions, follow the steps listed here to inspect and repair the wiring and reprogram the trailer module (TRM).
1. Reprogram the TRM using the latest available software.
2. Inspect connector C405 for corrosion. If present, replace the wiring harness(es) of the affected connector and apply Motorcraft Electrical Grease to the terminals and reconnect C405.
3. When replacing the 15K868 harness, the 4-pin trailer tow connector on the new harness assembly is to be cut approximately six inches from the 4-pin connector end. The cut-off 4-pin trailer tow connector should then be soldered onto the new harness. Be sure to pre-install the service kit’s dual-wall heat-shrink tubing. Do not use the butt splices provided with the service pigtail kit 5U2Z-14S411-JA.
4. Dry the connector C405 of any moisture and apply electrical grease to the terminals and reconnect C405.
5. Replace C4098 with the service pigtail (heat shrink tubing and soldering). Do not use butt splices.
6. Inspect the trailer side connection terminals of the 4/7-way connector that is mounted to the rear bumper. If corrosion is found, replace the 4/7-way connector. If no corrosion is found, dry and apply electrical grease.
