Hi I am installing a trailer electric brake

Congrats, you have found Ford's super secret fuse that drove everyone mad for years!

This link will tell you all you need. https://rv-roadtrips.thefuntimesguide.com/electric-brake-controller/

Toyota Landcruiser Prado Service Manual

get your car fix right now

cruise controls need all of the following sensors to be in line to work
VSS sensor (road speed 0
tacho (engine rpms)
brake pedal sensor
clutch pedal sensor
power to the unit (fuses)
any one unit not performing will stop the cruise control from working

We can supply brake boosters for Toyota land cruiser , year : 1985-2008,
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http://www.fiverhope.com/category-67-b0-Brake-booster.html
http://www.fiverhope.com/category-4-b0-Brake-caliper.html

yes all brake boosters have to have a vacuum line

Call dealer & ask them to run your vin# to see if it came with towing package. They shouldn't mind. If not, you'll have to wire it in yourself.

The connector is not under the dash. It is under the driver side seat.

try http://www.etrailer.com/faq-wiring.aspx. This should help.

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