Printer Friendly Forum Posts - Problem after installing a new head unit

My car is a Honda Accord 2002 V4 sedan. I've been searching around on this site as well as others but haven't been quite successful yet. I'll try to give out as many details as possible, so I beg your pardon if my post seems to be too lengthy.

Last week I tried to replace my factory head unit with a Kenwood HU. I got a help from my buddy and we finally got it to work. However, we found that there're two extra wires left unused: orange (illumination) and ORANGE / white (dimmer). At that time, we thought the orange wire is supposed to go to a power wire and the ORANGE / white one is its corresponding ground. So we made a huge mistake by connecting the orange wire to a red wire (+12V) and the ORANGE / white to a black (ground). Sure enough, we saw a spark, but the radio still worked just fine. We found out that the parking lights and the tail lights were out, so I checked all the fuses and found a blown one (small light fuse) and had it replaced with a new one.

One problem solved, yet another one was about to show up. Now that I learned that the orange and the ORANGE / white wires are to be left unused and separately terminated, we were about to finish the installation. But when we checked the headlights, we found out that we could never get the instrument cluster's backlight to turn on, no matter where the headlights switch was on or off. And yes, I did check that knob that adjust the brightness level. All other lights, however, were still working alright, including those on the cluster (ABS, SRS, etc.) as well as those on the dashboard.

So I tried putting the stock stereo back. The stereo backlight was on when I turned on the ignition. But after I switched on the parking lights or headlights, it went out immediately. I pulled out every single fuse in my car, including those under the hood, and carefully checked all of them with a multimeter. All of them are okay.

The search continued: I thought it might be a faulty dimmer knob, so I took out the instrument cluster and looked at the printed circuit board. I checked the potentiometer (rheostat?) with a multimeter and there's nothing wrong with it. Then I traced the connection to see which one powers up the backlight bulbs. The two wires are red and RED / black. I checked the voltage coming out of these two wires. Both of them give +12V constant regardless of the headlights switch position, and that's why the cluster backlight never came on. I also tried using a power supply to feed +12V to check if all light bulbs were okay and if there's anything wrong with the PCB itself.

Now I'm trying to narrow down the problem. Fuses are okay, the stereo works find, the instrument cluster is good. Could it be the headlights switch itself? If so, I think I ran into another major problem. It seems, at least to me, that I need to remove a steering wheel first before I can take that switch out. Frankly, I'm too afraid to do that since I may do something wrong again and cause the airbag to pop out (ouch!!). I could go to a nearby mechanics and ask him to do that for me. But then I've never seen one before, so how can I tell if the switch is faulty or not? And if it's not, then what else could be the cause of my problem?

I'm curious to know if both red and RED / black wires are supposed to give out +12V when headlights are off and one of them drops to zero when headlights are on (so that the instrument cluster will be backlit). And are there any other 'experiments' that I should try in addition to what I've done as mentioned above?

I'm seriously thinking about buying an Accord manual so I can look at the wiring diagram and get a better idea. But if someone can enlighten me, I'd be very grateful. I'm too tired of driving without seeing how fast I'm going (I'm afraid I'll get a ticket too).

Many thanks in advance.