My speedo doesnt work. the sp alternator fuse keeps blowing when I replace it. I had the car checked at autozone( check engine light) and the code came bad o2 sensor. Could that be the reason the fuse keeps blowing? its a 97 civic dx. Its my moms car and when she drives it when the fuse blows the lights dim and go back to normal dim etc.

 

There was a Honda technical Service Bullitin about a very low number of EK's with alternators sporting bad voltage regulators and the #1 symptom was the lights flickering as you described. My 98 was one of these lucky cars. honda wouldn't warrenty it even though there was a TSB and I worked for them. it's a very easy diag. you will see low and/or erratic voltages on the battery when the car is running.

Also on that model the cat cracks where the primary O2 bung is and sometimes a cat code comes on first and sometimes and O2 sensor code. Make sure that the light is on when you go to Honda and it will be replaced for free if the car is under 80k and on some years even later. there was a stupid overlap year where they kept using the faulty cats but cut the extended cat warrenty off before upgrading the part.. go figure. Can't remember what year off the top of my head. hope this helps.

 

Also check the engine wire harness that goes under the intake manifold. There is a brown wire in the loom that rubs through and shorts to ground.
This will cause a VSS and O2 sensor fault @ the same time the alternator will not charge due to the blown fuse...
You may also get a "electrical load detector circuit" fault...

Happened to my 98 DX as well...

 

Could a bad alternator be it. i pulled the negative wire off the batterie and the car shurt right off, but there was no fuse in it cause it keeps blowing.

 

your alternator wont charge w/ that fuse removed or burnt out.
What are the exact codes your throwing?

If the fuse is blowing,you probably have a short to GND. That fuse goes to a brown wire to your alternator. Try this. Wiggle the harness under your intake manifold and put the fuse back in...

Im willing to bet your engine harness is rubbing through the intake manifold support. Repair the wire and zip tie the harness away fro the bracket...

 

This happened to my car 2 days ago.After replacing the alternator and speed sensor with new ones I was still having the same problem.Car kept throwing the O2 and vss code.Did a search on here and found this post and decided to try what PyroProblem suggested.I was surprised to find not one,not two but three wires worn right threw.Taped the expossed wires up and zip tied the harness nice and tight to avoid any vibrations to it and presto problem is gone!!!!
I wish I would have came accross this post before I spent $300 on a new alternator and speed sensor.It's kinda of a bitch to do on the floor in the driveway so if you have access to a hoist use it.PyroProblem if I lived close to you I'd buy you a few beers as I was ready to drop the car off at an electrical speacalist.


BTW does anyone know what would happen if I took that stupid intake manifold support off?I dont like how all those harnesses are so close to it.

 

Very weird because I have the same problem going on right now. Yesterday, I pulled off my downpipe and I have an O2 sensor harness that is extended because the bung on the Greddy DP is way up by the manifold, so every since I unplugged the O2 sensor weird things have been happening. My speedo went out first, actually making erratic readings of like 120mph at a complete stop, and then later that night, the car eventually went dead.

I first then thought, damn, my alternator took a crap, so then I got a new one, and it still happened. Then I started pulling fuses, and came accross fuse #15 alternator, SP Sensor and figured my speed sensor was out. I didn't replace it yet, and thankfully I didn't because if the O2 sensor could possibly be the cause then that would be excellent. I have 2 more lying around in the garage and I'll just make sure the wiring isn't rubbed through. Also, how many pin connector is the harness under the IM?? Just want to make sure I'm looking at the right one, otherwise I will just look it up on Online All Data at work. Good luck on your heavy diagnosis Hope this is easier than I thought it was going to be.

 

my speedo is all messed up as well, and im throwing these codes.

20- electrical load detector
41- primary oxeygen sensor heater

we will see what happens... good luck with your problem.. i just found the post searching to fix mine

 

Old thread, but a friend of mine is having similar issues with his Civic. For those that have had issues with wires rubbing on the intake manifold, can you tell me which bracket they are rubbing on? Is it number 12 in the picture below?

 

Check the o2 wires and make sure they didnt get frayed anywhere and are grounding out.. I have seen this many times.

 

i just had the same problem, I went outside found the wire behind the mani. and BAM problem fixed.Thanks alot whoever figured that out.