Fuse problem on CRX

I know this is not a directly IT related question but maybe some of the CRX gurus here can help.

My street car, a 91 CRX Si, is blowing the 15A Stop/Horn Fuse in the engine bay fuse panel everytime I drive the car. This leaves me without brake lights which is not a good thing. No changes have been made to the car recently, all bulbs look to be in good shape as well as the sockets. It happens while driving for 10 or 15 minutes. I can put a new fuse in and sit in the driveway pressing the brake pedal all day long and not blow the fuse. I tried that with the car on, off, with lights on, lights off, blinkers, pressing horn, clutch in, clutch out, with reverse lights on, stereo on, stereo off, you name it I think I have tried it.

Only response I have gotten from other boards is "put a 20A or 30A fuse in instead" but I would like to find the problem not try and rig it up to work. ANy ideas here guys?

thanks,
Jason F.

It sounds like this is happening under engine load. If it is happening when the engine is >2500 rpm then it might be related to the voltage output from the alternator. I would check what the alternator's output voltage is under load and maybe this fuse is the weak link.

Honda's wiring and electronics are second to none. This means that it sould work perfectly forever, if the wiring is not tampered with. A 11 year old Honda usually has had some butchering of the wiring harnass to install "kid" accessories like an alarm system, stereo and all kinds of different gagets. I would investigate the entire wiring harnass under the dash and hood, and look for any evidence of any previous tampering and go from there.

The car did have a good bit of "kid" accessories when I bought it. The first thing I did when I got it home was remove the car alarm, the aftermarket power windows, aftermarket power door locks, remote keyless entry, and botched stereo wiring none of which worked correctly. Anywhere there was a splice into the original harness I removed the splice, reconnected the original wiring, soldered my connections, and rewrapped with electrical tape and/or heat shrink. I am no electrical expert mind you but everything was working well.

Now over one year later this happens, so I am going to have the alternator checked after work today and while there pick up all new bulbs for all the lights and some lithium greese for the sockets. That should be cheap enough and will eliminate them from the picture as a problem. Beyond that I want to check and possibly replace all the grounds in the car. How many ground straps are there in the engine bay and in the dash/fuse panel. I know there is the main ground from the negative battery terminal to the tranny and the one form the valve cover to the rad support. What else is there?

Thanks,
Jason F.

There is several ground to chassis connections on the CRX. There are at least 3 under the dash, lower b pillars, rear tail section and connections under the hood at the headlights, etc. Borrow a Honda shop manual and check the grounds in the electrical section. Honda shop manual has excellent electrical schematics.

I suspect eithor the alternator or one of those "kid" accessories as the culprit.

The alternator checked out good. No spikes or odd voltages/amperages at idle, 2500, 3500 rpm's.

I suspect a damaged or shorting wire in the light harness somewhere. I have my Helms in digital format so I will have to start digging for wiring schematics. Thanks for your tips on the diagnosis.

Thanks,
Jason

Have you replaced &/or checked all of the bulbs? I have seen on several cars in the past where the lead contacts on the end of the bulb actaully mushroom so bad that they are either touching or with the right bump/movement will touch and cause the system to short, just a thought...

------------------
Gordon Galloway
Honda CRXsi
IT2 #32

Yep replaced the rear brake light bulbs, third high mount brake bulbs, blinker, and parking light bulbs since I had it all apart. I checked the sockets for damage and ran a finger wrapped in snadpaper inside them to clean out any buid up of junk then treated all sockets and bulbs with a little Dielectric greese. I also pulled the entire rear wire harness and checked for chaffing, rubbing, or other damage and found none. I also spent an hour or so under the dash looking for any wire issues there and found nothing of concern. Supposedly the only thing else on the same circuit is the horn, the Helms seems to confirm this so I am going to trace as much of the wiring in the engine bay as I can next. I had to spend last night replacing one of the rear hubs so I did not get to fiddle with this problem any.

Thanks,
Jason F.

Does the car have an aftermarket steering wheel? If so, check the wiring at the horn button, there could be a short.

Jon

Well it did have an aftermarket wheel but it had no horn button. It is all irrelavant now as the car caught fire last night. It did not burn to the ground or anything but it toasted the entire electrical harness and who knows how many sensors or electrical components. The car is pretty much a right off as it was not in that great of shape to start with.

Later,
Jason F.

When in doubt put in a bigger fuse and look for the smoke!!!! That's too bad to hear that it smoked a little to much. Why did it smoke this bad? Did you put in a bigger fuse?and the next thing is is it available as a parts car now?

I have yet to decide what is going to happen to the car. If I find another CRX it will become a parts car, I might part it out, and I might use it for the start of a ITA project.

Jason F.

Sorry to hear that. I was going to suggest looking in the taillight housings for water. 88-91 CRX's and Civic's are notorious for water draining down from the hatch and directly on top of the taillights - the foam gasket over time develops leaks and the water runs right into the housing. When it gets deep enough, it'll slosh into the sockets and blow the fuse.

A solution (the one I used) is to silicon the the foam gasket to the taillight housing and then silicon that assy. to the body. This will keep the water out of both the housing and your spare tire well. I also ran a bead of silicon across the lens/housing seam on top....

Maybe this info will be handy in the future.

I actually drilled 1/8" holes in the bottom of my tail lights in my CRX. What goes it, just drains out!

Yep I checked the housings. In fact I resealed one housing that was slightly cracked at the seam and then like you ran a bead of silicone on both sides of the gasket. Those tail light housings are the biggest cause of water in the hatch area followed closely by the sunroof drain tubes.

Jason F.