Blue Ox BX8847 - Manual (Page 2)

292-1304 Page 2 of 3 10/2001
9. The back door threshold is similar to the front. Pull up the threshold to gain access under the
carpet. Run the wire harness around the center post (you may need a piece of stiff wire to help
push the wire through) and along the back door and into the back seat area. Replace the carpet
and thresholds.
10. Under the driver’s side of the back seat there is a plastic loom. Open the loom and pull out the
wires. You will find several light blue colored wires. These wires are used for the brake lights.
Have someone step on the brakes and use a needle point tester to determine which blue wires
are used for the brakes. The other wires may be “hot” when the stereo is on, so the stereo system
must be shut off while you are identifying wires.
11. To identify the left and right brake wires you will have to cut the wires one at a time and see which
light goes out. If you cut the center brake light wire splice it back together. When you have
identified either the right or left wire, strip the ends and crimp on female spade terminals Plug
the female terminal from the front of the car into the “in” side of the diode block and the female
terminal from the rear of the car into the “out” side of the diode. Repeat the process for the other
brake wire. When both diodes are installed, test the brakes to make sure they work again.
12. Cut any excess wire off of the four wire harness. Leave about 6 to 8 inches of slack. Separate
the four wires. Start on the outside and carefully peel each wire back about 6 inches. Cut off the
white wire you peeled back, it will not be used under the seat. Inspect each wire to make sure
there aren’t any bare spots showing. Wrap any bare spots with electrical tape. Strip each wire
and crimp a female spade terminal on each wire. Plug the green wire into the right brake diode
block. Plug the yellow wire into the left brake diode block.
13. There are several brown wires in the loom. Depending on your model, there will be 2 to 4 of these
used for the tail lights. Turn on the tail lights and use the needle point tester to identify the tail light
wires. (Remember, stereo must be off.) When all are identified, cut all the wires, strip them, and
twist them together. Crimp on a female spade terminal. Plug the female terminal from the front
of the car into the “in” side of the third diode block and the female terminal from the rear of the car
into the “out” side of the third diode.
14. Plug the brown wire from the four wire harness into the “in” side of the diode block. Test the car
tail lights to make sure they work.
15. The last part of the wiring is to ground the four wire harness. The white wire is the ground. In the
engine compartment find a bolt near the wire harness that will provide a metal-to-metal contact.
Carefully cut just the white wire and peel back enough wire to reach the selected bolt. Strip and
crimp the ring terminal on the wire. Remove the bolt and place the ring terminal under it and
tighten. NOTE: If you are installing a 4-wire or 6-wire trailer plug on the front of the towed vehicle,
then you may insert the ground into one of these terminals to provide a ground for the system.
16. Secure the four wire harness several places between the grill and the front of dash to keep the
harness from getting tangled up in moving parts or touching engine parts that will get hot.
17. Hook up the towing vehicle to the wire harness and test the installation by operating the tail lights,
turn signals, and brake lights. If the wiring on the towing vehicle does not match, you will need to
change either the wires in the back seat or on the towing vehicle to match.
18. When the installation is working properly, replace wires back into the plastic loom in the back
seat. Use electrical tape to secure the rest of the wires together. Lay the diode blocks and wiring
as flat as possible against the floor under the seat. Replace the rear seat. Be sure to feed all the
seat belt straps and buckles through the holes in the seat as you replace it.