AjHawk

If I unplug the alternator then how am I going to drive the car for 5 or more minutes without killing the battery? And should I pull the fuse box and unplug the eld or remove it altogether?

Former User

I think a fully charged battery will last long enough. Be sure not to use any electrical accessories during the test and stay close to home.

This^

I think it has a 3P connector on the bottom side of the hood fuse box.

By the way, I should have also added the dash fuse box to my list in post #49 (edited).

AjHawk

So if I rule out the alternator and eld, and already know that all those Evap connections have not been plugged in at all during this adventure, it could be in the fuse box under the dash. Ouch.

AjHawk

Drove it with the alternator unplugged and all was good, plugged it back in, revved up the engine and the fuse blew. It is a brand new alternator. Would that point to a short in the wiring between Alt and ecu?

Former User

Lifetime warranty alternator? If so, return for replacement.

tony_2018

So which harness are you using now?

AjHawk

Pulled the connector for the ELD (lots of dielectric grease in there), green/red wire has 1.1k ohms to ground. Sensor unplugged has 47k ohms between green/red and solid black. OL between all other sensor combinations.

^All good there?

AjHawk

^Doesnt matter now.

Unplugged; alternator, VSS, both o2 sensors, and ELD.
Still blows fuse 15 and loses all power once it warms up.
Still runs great until that happens.

crazyhouse2011

I'm not entirely sure the secondary O2 will affect your engine performance in any way. It's just a tattletale sensor, ie it tells the ECU that your primary O2 and Cat are doing their jobs.

Former User

Informative.

Manual or auto transmission?

Test:
Try also unplugging cluster connector B, all EVAP valves, and the integrated control panel on the rear of the dash fuse box. Does fuse 15 still blow?

Test:
Unplug connector C421 on the rear of the dash fuse box. Does fuse 15 still blow?

AjHawk

I left everything unplugged that already was and I disconnected the c421 connector. Started it and went for a ride, as usual, drives like normal and everything is good. After about 10 minutes I get back, come to a complete stop, as I attempt to pull forward, its back. Engine breaks up and misses. If I floor it, it will backfire. Idles perfect, revs up in neutral perfect if I dont floor it, if I floor it in neutral it misbehaves like usual. Put a load on it (in gear), falls on its face. Never tries to stall though I noticed, just run like crap.
Manual transmission.
Edit: it does not blow fuse 15 now, im guessing its because you had me disconnect c421 though.

AjHawk

Car is currently warm.
MAP @ idle .99-1.02v or 32kpa
Fuel injection @ idle 2.8 msec
ECT is 90 degC
BARO @ idle 2.79v or 97kpa and doesn't move
Spark advance @ idle 22 deg
@ 2500rpm is 41 deg
FTP is 3.12v or 10kpa and doesnt move

Former User

This^ is critical new information because it tells you that the poor driveability and fuse 15 blowing are two completely separate issues.

And if unplugging C412 definitely prevents fuse 15 from blowing, then you know the short is somewhere downstream of C421 in the circuit and not in the dash fuse box.

Former User

Before or after driveability issue begins?

glen_zam87

Hi, i'm from mexico, and have a 00 civic ex with exactly the same two problems like AjHawk, do you fix this issues in some time? sorry for my poor english

Former User

Check the two O2 sensor wires for a short.

LeroneP

Hey, I'm a new member here. I recently purchased a 1998 Honda Civic Hatchback. I revved it one morning while going to work and i heard a cracking sound, the car lost power and i then saw smoke coming from under the dash where the fuse box is located. I checked and found the No. 15 fuse blown. I changed it and went back home and park the car. The next day I drove it the fuse blew again, and i smell something burning and smoke coming from under dash again. When i checked i realize that the no. 14 wire in the connector C421 connected to the back of the under dash fuse box leading to the main wire harness and connected to the engine harness was badly burnt. In so much that it also melted the insulation of other wires. The burnt wire is connected to the black wire with a yellow stripe that connects to the alternator.
I repaired the wires, replaced the burnt one, replace the fuse and it cranked but didn't start and when i checked the fuse was blown again. I proceeded to inspecting the entire engine harness and there is no sign of and burnt or chaffed wires beneath the intake manifold. The connections on the alternator looks fine too.

Can someone please tell me what could have caused the wire to burn that bad and constantly blowing the no. 15 fuse.

PS. The area around the fuse also slightly melted.

tony_2018

Wires crossing somewhere. Looks like you're gonna have a field day under the dash.

LeroneP

Ok.....I plan to go at it this weekend. Thanks