As always, I nor Ford Ranger Forums is responsible for any damages to you, your property, or anyone you may injure while undergoing this modification.
Ever want to turn on your radio in your truck without leaving your keys inside, or just want to get rid of that awful chime noise for this use? Well, this is the writeup for you! This system will allow the radio to function as normal with the key on, but with the added benefit of being able to turn it on at will.
For this, you will need the following items and materials:
-One 5 pin relay and one four pin relay
-A switch of your choice. I chose a chrome 'racing' switch with a hood because I can.
-A few different colors of wire for ease of installation
-An assortment of connectors
-An inline fuse with a matching fuse for your radio. Mine is rated at 7.5 amps, so that's what I'm using. If yours is 30 then use a 30, if yours is 10 use a ten and so forth.
-Some basic tools, including wire cutters/crimpers/strippers, multi-meter or test light, 8 mm socket with ratchet to remove the bezel, and maybe some pliers if your connectors are unusually tight.
Now here's how it works for those of you unfamiliar. R2, when left deactivated, allows current to pass from P30 to P87A uninterrupted, so the radio acts as it would while the key is on. When you turn the switch on, R2 is triggered and the line between P87A and P30 is cut, preventing power from flowing backwards to the rest of the truck as if the key were in the 'run' position.
R1=Relay 1
R2=Relay 2
P## = Pin Number
Here's a schematic.
The pin wires are colored to match this harness, although you do not have to follow the same color pattern, just where these wires end up going.
It is important to note that the grey and blue wires cross over each other but DO NOT connect to each other. Places where wires connect are marked with a black circle. Grounds are also marked with their respective schematic symbols. It is also worth noting that R1 does not have to be a five pin relay. A four is better suited, but I only had five pin relays, and thus marked it as being one.
If schematics aren't your thing, then here is the written version:
Of course, P85 on both relays connects to ground. You can ground these wherever you please.
P30 on R1 connects to an inline fuse going directly to the battery, through the firewall.
P30 on R2 connects to your radio's power wire. For my 1999 this wire is yellow with a black tracer. Be sure to confirm with a multimeter or test light. Snip the wire and attach the truck-end to P30, again on R1
P86 on R1 and R2 connects to the output side of your selected switch.
P87A on R1 is left unused and taped off.
P87A on R2 connects to the radio side of the wire we cut earlier.
P87 on R1 connects to the radio side of the wire we cut earlier.
P87 on R2 is left unused and taped off as well.
I should mention one critical mistake I made while building this inside the vehicle. I had mistakenly taken power from P86 to power the radio on P87A, both on the second relay. However this causes a major problem that doesn't really hurt anything, just irritating and nothing will work. When P87A received power from the key, it would trigger the relay to turn itself off, via backfeed causing it to 'click'. However, now that power is no longer flowing to P86 the relay clicks off and the cycle begins again. If you run into this problem, ensure that your hot lead going to the radio is separate from any and all leads going to either P86 pin, no matter which relay.
Power then flows from P30 to P87 on R1 all the way to the radio, bridged onto P87A on R2.
Now, where is the switch getting its power. The battery saver relay, of course. We can grab this wire behind the radio bezel. The wire you're looking for is light green with an orange tracer. You can either T Tap into this wire or solder in.
And that's pretty much it. Word of warning, make sure to use the proper size fuse in the inline fuse holder coming from the battery. My radio has a 7.5 fuse in it already, so I used a 7.5 amp fuse in the fuse holder. Never use a higher amperage rating.
As for the switch, it doesn't have to be anything special. A simple on/off switch will work fine. Push button, toggle, rocker, any kind you prefer.
This is what I chose for those of you wondering:
Enjoy your new key-less (sometimes) radio!
Also a 'thank you' to Grampybox who pointed out a few items which weren't very clear.