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.

wow, you were right about the long post. yes, from my experiments (and failures) I have found out that when the headlights switch on, one of the wires switches to negative, also called a negative trigger. The parking lights, however are opposite, using a positive trigger to activate. so, you said that you pulled out the dimmer switch and tested those wires, heres one thing you could try, give a positive and negative voltage to those wires and see what happens, if the lights come on, then you probably fried your switch. Another thing you could try is taking out your instrument cluster and looking at the back of that to see if there's any burn marks and what not. you could also, while you have it out, check the bulbs to see if there still okay. And, while it's out, you could test the wires that plug into the cluster and see if you can find the one that switches with the headlights (if it still works). But, come to think of it, sorry, the first thing I would do, if you haven't already, it take the steering column plastic down and check the wires up there. If you can get the top plastic off, the headlight, parking, and all that sutff should be sitting right there for you to play with. And if it comes down to it, and you have to take your steering wheel off, obviously the airbag is very important. You just want to make sure that you unplug it first, before you do anything else, and when you unplug it, make sure you're not touching any wire with a positive or negative current at the same time (which is pretty hare to do). Most of the time, Honda's will have an access panel underneath the wheel to do this. then just look for other panels or hidden screws and have at it. And DON'T turn the car on with the airbag out or unplugged, that's I big mistake that you don't want to make. Sorry for my long post, but I hope that some of this will help you. Good luck and godspeed.

So we made a huge mistake by connecting the orange wire to a red wire (+12V) and the orange/white to a black (ground).

Did you guys read the instructions? Every CD player I have ever installed says the those 2 wires may not be used, and to just cap them off. If you would've done that you would have never had to go through this whole mess. At least now you know!

wow, you were right about the long post. yes, from my experiments (and failures) I have found out that when the headlights switch on, one of the wires switches to negative, also called a negative trigger. The parking lights, however are opposite, using a positive trigger to activate.

Hm.. so my guess was correct then. Now I got another question: why are the clock and the stereo lights on when I first start my car (without parking lights or headlights on)? They're off when the parking lights or headlights are on, just like my cluster. I thought all of them (clock, stereo and cluster) are wired to the same controlling circuit. So if my cluster light is never on, then the clock and the stereo lights should never come on either, should it? Anyway I'll go check the illumination wire at both places.

so, you said that you pulled out the dimmer switch and tested those wires, heres one thing you could try, give a positive and negative voltage to those wires and see what happens, if the lights come on, then you probably fried your switch. Another thing you could try is taking out your instrument cluster and looking at the back of that to see if there's any burn marks and what not. you could also, while you have it out, check the bulbs to see if there still okay. And, while it's out, you could test the wires that plug into the cluster and see if you can find the one that switches with the headlights (if it still works).

Yeah, I did those already. The bulbs are all okay. The wire that's supposed to switch with the headlights doesn't do so; that's why the cluster light isn't working properly. So I kinda believe it must be the headlights switch that got fried. I always thought that mechanical parts, like this switch, are able to tolerate a current surge better than electrical parts. This proves that I'm totally wrong, or could it be just my bad luck?!?

But, come to think of it, sorry, the first thing I would do, if you haven't already, it take the steering column plastic down and check the wires up there. If you can get the top plastic off, the headlight, parking, and all that sutff should be sitting right there for you to play with.

I already took off those plastic cover pieces. The problem is I couldn't find a wiring diagram of the headlights connector, so I don't know which wire I should test. Would it be the same color (red and red/black) as the one going into the cluster? Do you know where I can find the diagram? Like I said, after having so much trouble, I'm gonna get the service manual eventually. But if I could fix it right now, then it'd be great.

And if it comes down to it, and you have to take your steering wheel off, obviously the airbag is very important. You just want to make sure that you unplug it first, before you do anything else, and when you unplug it, make sure you're not touching any wire with a positive or negative current at the same time (which is pretty hare to do). Most of the time, Honda's will have an access panel underneath the wheel to do this. then just look for other panels or hidden screws and have at it. And DON'T turn the car on with the airbag out or unplugged, that's I big mistake that you don't want to make. Sorry for my long post, but I hope that some of this will help you. Good luck and godspeed.

Wow.. after reading your guide and caution, I think my adventure shouldn't go that far. Just imagine how inexperience I am that an easy stereo installation is giving a hard time already, I'm very certain that I might run into another big trouble.



Thanks a lot for your reply!!

Did you guys read the instructions? Every CD player I have ever installed says the those 2 wires may not be used, and to just cap them off. If you would've done that you would have never had to go through this whole mess. At least now you know!

Actually we did. But we read the one that comes with the harness first. It says the orange/white wire is the illumination ground and that made us think that we had to hook it to ground. But after we saw the spark, we knew something went wrong and did a further research to find out later about not using these two wires.

It was kinda fun at the beginning, that I got to learn several new things about my car. But now it's been about a week already; the fun has died out and I just want to get it done.

If you got any idea, please let me know, okay? Thanks a lot.

I already took off those plastic cover pieces. The problem is I couldn't find a wiring diagram of the headlights connector, so I don't know which wire I should test. Would it be the same color (red and red/black) as the one going into the cluster? Do you know where I can find the diagram? Like I said, after having so much trouble, I'm gonna get the service manual eventually. But if I could fix it right now, then it'd be great.


What you could do, if you don't mind waiting a little longer, is go on Ebay and find a factory service manual on CD. They usually have complete wiring schematics and are usually pretty cheap. I think I got mine for like 10 bucks. Then I just uploaded it onto my laptop and now I have it everywhere I go.

Other than that, city libraries usually have some Chilton and Haynes' manuals, but I don't know exactly whats in those. Good luck. Oh, and I tried to find wire colors for you but I was unsuccessful. You might wnat to try searching the net, and maybe you'll get lucky in that respect. Again, good luck.

Do you have marker/tail lights ?

As mentioned, see if your library has online access to the Alldata or the ARRC sites they have wiring information for most models.

In had the same situation, and it is right - don't connect the orange wire!

I have a question for you, seeing as how you have already done something that I NEED to do with my 1998 Accord - same as your 2002. I need to remove my dashboard instrument panel (speedometer cluster) to replace a burnt out bulb behind the gas gauge. The two obvious screws on the underside are removed, but it wont budge! Can anyoen direct me as to how I can pull out this cluster?

Thanks!!!!!!!!

In had the same situation, and it is right - don't connect the orange wire!

So how did you fix the problem? My cluster light is still not functioning properly, i.e. not illuminating when I turn on the headlights. I even bought the Honda Factory Manual but it doesn't give me much information.

I have a question for you, seeing as how you have already done something that I NEED to do with my 1998 Accord - same as your 2002. I need to remove my dashboard instrument panel (speedometer cluster) to replace a burnt out bulb behind the gas gauge. The two obvious screws on the underside are removed, but it wont budge! Can anyoen direct me as to how I can pull out this cluster?

Thanks!!!!!!!!

Do you mean the black plastic piece that you have to pull it out first? After removing those two screws, just pull it out. The clips are on the bottom, by the way.

i installed a new kenwood radio and tha same problem my cluster doesnt work i dont have memory in my radio y checked the positive cables from the bulbs of the cluster and both have postive energybut when i came to the fuse box i had groung in them most of them know im driving blind with out my cluster and each time i start my car oi have to reset the radio could you guys help me ??