Do You Have to Run the Power Cord to Battery on 4flat Trailer Wiring on 2001 Saab 9-5

Updated 12/15/2025 | Published 11/09/2024

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Question:

Can your Curt or Hopkins adapters for the Saab 9-5 use the factory supplied connector in the spare wheel well for power as well as signals/brakes/ running lights? According to the factory pin out, there is supposedly a 30 Amp supply on pin 9 originating on fuse A.

asked by: John

Expert Reply:

Hello John.

I have heard of people splicing into that wiring connector in the wheel well. However, it is recommended to run the power cord to your vehicles battery. This is to ensure that the converter is getting the right amount of power to run the trailer lights, which in return also protects your vehicles sensitive electrical system. By installing the wiring any other way than what the manufacturer recommends can be harmful to your vehicle. I have also attached an article about routing the power cord and why it is needed.

As far as connecting the other wires like you signals, brakes, and running lights it would be fine to splice those in. The wiring on the vehicles can sometime be different so I recommend using a circuit tester like # PTW2993 to ensure you are connecting the right functions as sometimes the colors will not be the same. The Hopkins Active Tail Light Converter with Install Kit # 46255 that you were looking at will work great for you 2001 Saab 9-5.

expert reply by: Kate F

Kate F.

12/15/2025

Hey John, how did things go with wiring the Hopkins converter on your Saab 9-5? Did running the power wire to the battery work out as expected? Your update could make it easier for others tackling the same setup.