wvuFan

Hello. I'm sure long-time members have seen/heard this issue a lot before, so here it goes. I have a '98 Civic DX 5-speed that started with a CEL and sporatic speedometer. Took it to auto store and it shot out error codes related to bad 02 sensors and engine overload ??. came home, Googled the error code and found a suggestion that those codes may point to blown fuse. low and behold, i checked under dash fuses, and under hood fuses, all were ok except the 15 (alternator and SP sensor) 7.5a fuse which was blown. I replaced it and turned to the car to ON and the CEL went out. I then started it up and the CEL stayed off and the speedometer was back working... for about a day. I actually took it back to the same auto store about 30 minutes after I "fixed" the issue and their same OBD tool didn't pick up any codes. the codes magically disappeared/cleared themselves, which they said was strange. Either way I was feeling good. But this morning I took a neighbor to work and everything was cool until I was driving back and then the CEL came on and the speedometer went all crazy again. checked and the same 15 fuse was blown again. i figured, another fuse, another resolution. well this time, the CEL wouldn't go off and the speedometer still wasn't working properly. and the 15 fuse was blown. now the fuse change doesn't fix the issue..i mean it does while at the ON position. but when I start it up, the CEL shines and the fuse is blown again. auto store again OBD tool this time shows p0500 speed sensor, p0135 O2 #1, p0141 O2 #2. before i purchase any of these i assumed that any single part/unit such as an O2 sensor and/or VSS would continually blow a fuse. which means there is an issue with wiring or something. i've researched and found the 99-029 Honda Service Bulletin .pdf to show the possible cause and solution with the wiring harness rubbing on the manifold intake bracket. not good enough weather currently to get up underneath there and examine that possible fix yet. But i did examine under the hood and the wiring, etc. and found that some wiring on the harness almost directly underneath the brake fluid reservoir shows signs of some 'creature" nibble marks and exposed wiring (possibly colored at least black and red)I tried to get good pics. I attached to this post. after all that describing me issue, my question is can anyone identify what connector number this goes to. i cannot find wiring diagram. and would it be safe to assume that these exposed wires could be causing my seemingly random problem of fuse 15 constantly being blown? i know any wire exposion isn't good, but it doesn't seem to be near the harness underneath at the intake manifold bracket. any thoughts/suggestions would be appreciated. thanks in advance. have a good one. p.s, i also attached the Honda issued Export Service Bulletin for anyone who may need to try checking the wiring harness at the intake manifold bracket steps.

another view of exposed wiring

another view of same exposed wiring

tony_2018

That SB is for the engine harness. What I'm looking at seems to run along a frame rail. I would still advise you to repair that wiring and inspect the rest of the harnesses in the engine bay.

mk378

Those wires may also be bad, but the main problem is behind the engine. You can disconnect the back branch of the engine harness from everything it connects to then pull it out toward the right side of the car for easier repair. That still really needs getting underneath the car for some of the work though. Driving up on ramps is the easiest way to do that at home.

Do not buy new sensors. The sensor codes are not because the sensors are bad, but because the sensors aren't getting power from the harness so they throw bad readings.