We wanted to be able to play our (digital) music collection in the van. After trying out an FM transmitter (that had horrible quality) we decided to replace the van’s original factory FM radio (which at the time of manufacture, was an upgrade, from no radio) with the cheapest radio we could buy that had an axillary line in connection (a.k.a. the “ipod jack”). We ended up with a $70 CD/AM/FM receiver by Dual.
Mecanically, the hardest problem was mounting the single DIN radio into the hole left by the previous (non-standard sized) radio. Lucky, the popularity of the 1979-1993 radio model our van had insured that I could buy a plastic adapter kit for only $25 with shipping.
Unfortunately, I made one key mistake when installing the radio (electrically). The previous radio had two power wires leading up to it (red and orange) that tested out at +12V and Ground when I measured them with my volt-meter. A separate wiring harness carried all of the speaker wires, so I felt justified in assuming that I should attach the +12 line to the red wire and the “Chassis Ground” wire to the orange wire. As it turns out, the original radio used the van chassis for it’s ground connection, and the orange wire was really a console light circuit. The console lights (orange wires) are normally held at ground when the headlights are off. BUT, when the headlights are ON, the console light wire floats somewhere between +12V and ground, depending upon how far the headlight selector lever is twisted. (This allows for adjustable console/instrument light brightness.)
Grounding this circuit out via the radio is BAD. However, everything works as long as the headlights are off. In fact, everything continues to work fine if the headlights are on, as long as the console lights are dimmed all the way to off. In actual practice, everything works for several weeks until you drive out of the state.
The problems start when the headlights are turned on and the selector knob is NOT in the fully dimmed position. First, the rheostat (a long coil of partially resistive wire, or a potentiometer) in the headlight switch begins to heat up, burring some plastic and causing a characteristic electrical burning smell. Then, if your driving companion convinces you that nothing is burning, and you don’t turn off the headlights, eventually the rheostat burns all the way through (destructively disconnecting the short). This stops the burning smell. However, the console lights do not illuminate. Then, if you twist the dimmer switch all the way counter-clockwise, the connection pad eventually reaches the “full-on” (or zero resistance) setting, and this allows 5 Amps to flow through the short circuit, and the fuse blows. (This is exactly why fuses exist. Fuses are good. They prevent fires, and are relatively inexpensive to replace. I personally replaced three of them before fixing the problem, but luckily I had bought a 5 pack.)
Finding the actual problem however can be very tricky. It involves buying a new headlight switch (because the rheostat is broken) and replacing it. Then, optimistically hoping that the headlight switch caused the short, and burning up a fuse finding out that no, the short is somewhere else. Then you have to buy a $20 repair guide (including wiring diagrams!) and trace all of the circuits (including testing each and every bulb hidden away inside of the dash, plus all the wires that lead to them) before finally realizing that the chassis ground on the radio isn’t shown on the wiring diagram, but of the two wires leading to the radio, one is +12V, and the other is NOT always ground.
This also involves driving around for two days with the dash off and instrument panel held on only by wires and (if you are lucky at the time) the speedometer cable. (We had to add 17 miles to one of our MPG calculations because I hadn’t attached the speedometer cable for that trip.) I did take advantage of the situation to spray a lot of WD-40 down the speedometer cable, which did a good job in reducing the sticking that was causing the speedometer pointer to bounce around our true travel speed.
Eventually I got both the radio, AND dash lights to work at the same time.