Originally Posted by rwenzing

Note: This is an unauthorized mod that I did to my 2003 Ranger for my own reasons. I present it here for informational purposes only. If you choose to do something similar, you do so at your own risk.

This is a simple mod that will provide power to the accessory circuit (including radio, power windows & wipers / washers) after the ignition switch has been turned off. The accessory circuit will remain powered until the driver's door is opened. As pictured below, it should work on 2001~2003 Rangers and possibly earlier years as well. The 2004+ Ranger is a different beast electrically and this will not work as written for 2004-on.

It requires 2 standard Bosch pattern SPDT relays which are available at the Ford dealer for about $7 each - a good one to use is a replacement for a Ranger's heater blower motor relay. It is easy to connect wires to the relay pins using quality 1/4" insulated spade terminals or special relay sockets.

All wires are readily accessible in the radio cavity with the radio removed. It may make things easier if the radio bezel is also removed.



NOTES:

***There are two yellow/black's in the drawing: one to the GEM and one to the HU. They have different functions and must not be interchanged nor connected together.

***The GEM module has two connectors. The yellow/black (yellow wire with a black stripe) to be tapped for the door open signal is in the connector closest to the front of the truck. CAUTION: There is also a black/yellow (black wire with a yellow stripe) in the same connector - be careful not to mix them up.

***I used 16 gauge wire throughout to match the truck wiring. The spade connectors and wire taps used should also match the 16 gauge wire.

***Pin 30 of the relay on the right side of the diagram should be tapped to the Black/Light Green wire of the dash harness going to the head unit. There are two of these Black/Light Green wires and the larger one should be used.