Radio Relay Trick
Use these relay systems to keep your head unit on until you open your door.
Using one of these two relay pairs will turn uour head unit on with the key as normal, but the head unit will stay on until you turn off the key and open the door. Be sure to use the top diagram for negative door triggers and the bottom one for positive door triggers.
DISCLAIMER: Check all wires before making connections,
and do not hold me
responsible for anything negative that may result from
you following these instructions.
This is a fairly simple procedure,
but it is always wise to check your wires using a multimeater, before
you make any connections.
You will need two 30 amp relays, I
recommend Bosh, or Potter and Brumfield, but any will
work. You will also need a 10 amp diode. I
once used a 6 Amp diode and did not have any
problems if you are unable to find a 10 amp. You
will also need to solder and heat shrink connections,
or use crimp connectors and about 10 feet of 16-18 gauge wire.
All the Fords I have done have had
positive trigger door switches. In the 98 and 99 F150 it is a
Black/Blue wire in the drivers kick panel.
I have a wire code sheet here for the 98 and it also says
that on the base model the door trigger is negative with
a Orange/Green wire.
If ya'll have any other questions,
feel free to ask,
Questions or comments:email me