Installing a T-One Wiring Harness Off a Power Source Instead of the Battery

Updated 04/13/2021 | Published 04/09/2021

Question:

Hello, I have a 2010 Volvo XC70 and bought the appropriate Hopkins wiring harness from you a few years ago. I assume I have the HM1143735 but it has no part number on the converter. Anyway, I easily did most of the installation and asked my mechanic to install the power wire to the front of the car as directed. Mechanic instead found a power source in the fuse box at the back of the car and made the connection there. Similar to what one of the reviewers Doug in STL mentioned. Everything worked great at first. Over time, I lost running light and brake light functions. I tested the output from the vehicle side and showed neither running or brake lights. I recently tested again and still show no running lights but now the brake lights signal and turn signals are lighting again on the 4-flat tester. Im guessing I need a new converter but am unsure if the problem is being caused by the power coming from the rear fuse area instead of direct to the battery. Obviously Im thinking I should wire directly to the battery next time, but as others have mentioned it is not easy. Thanks for any insight into this issue.

asked by: Nick G

Expert Reply:

For the Hopkins Plug-In Simple Vehicle Wiring Harness # HM11143735 the manufacturer does specify to run the wiring to the battery and use their provided fuse on your 2010 Volvo XC70.

My only concern with the running to an alternative source is if the correct amount of power is being supplied. The wiring that is ran through the vehicle that the mechanic used might not have constant battery direct power or enough amperage for the Hopkins harness. The wiring systems on vehicles as become very delicate and intricate where they now regulate the amount of voltage that runs though certain wires. For this reason I recommend routing your power wire directly to the battery.

You can run a temporary wire directly to the battery on your current module with the manufacturer supplied fuse to test and see if you module does still function properly or if a replacement is necessary.

expert reply by: Bud M