Troubleshooting 4-Pole Wiring Harness in 2015 Ford Transit Connect

Updated 10/25/2016 | Published 10/24/2016

Question:

light worked perfect at first then , quit working. How can I trouble shoot ,do you have a wiring diagram?

asked by: Dudley C

Expert Reply:

The T-One wiring harness you referenced, part # 118613 that fits your 2015 Ford Transit Connect, uses a 12V power wire and 15-amp fuse to deliver power to operate the harness. If the entire harness suddenly stopped working then the first thing to check is the fuse. You don't need a wiring schematic to troubleshoot.

The other most common reason for the harness to stop working is a bad ground connection. A weak ground could cause some light functions to work while others do not. Taillights, because they remain on all the time, draw more power and a weak ground may let other functions work while this one does not.

If only one or two functions have stopped working then the problem could be in the converter or in the connectors that plug in to the vehicle. Disconnect the connectors where they plug in to the van taillights. Check for any signs of discoloration, moisture, foreign material or corrosion within both the van and harness connectors. Clean as needed. Also check for bent pins; these can often simply be gently bent back up so that they again make solid contact.

You can refer to the linked article for more troubleshooting help.

expert reply by: Adam R