spider0735

I want to apologize before hand that I am quite new to working on cars myself so I may not be able to see all the connections and dependencies between parts.

Last Tuesday as I was going home on the highway, my catalytic convertor fell and was scraping the road creating sparks out the back end of my car. I was waiting for the next to take a look at it after I come home from school. To my surprise, it was towed due to the freaking snow emergency plow. Got it back and took out the cat. It was heavily scrapped through to the inside making it unusable. This cat has an oxygen sensor connected to it. *this is one concern that I will bring up later*

Since my younger brother also owned a similar model and year as mine which he no longer use, I decided to take out his. I took out from the down pipe connecting to the exhaust manifold to the end of the cat. now his cat doesn't have an oxygen sensor on it. I really needed my car to work again so I went ahead and replaced mine with his. I cut the female end of the oxygen sensor on mine and covered the other end under the car so dust and water can't get in.

Also, both of the down pipes that we have has oxygen sensors on them as well. The wires on his was old and out of the connector/socket. I couldn't get the wires back in and I wasn't able to get the o2 sensor out from the pipe. So I went to my next option and cut the wires on both the sensors and also replaced my end of the connector with his. I made sure that the wires matched and that they went to the right place. There were four wires on both of ours. His had a blue, a white, and two blacks. Mine has a green, a white, and two blacks. I soldered the blue to the green, the whites together, and the two black wires to the two black wires...based on their location on the connectors.

On Sunday, I got them hooked up, saw a pipe to combine the cat with the rest of my exhaust assembly. After that, the car never sounded so beautiful. I was almost so proud of myself to accomplish such a task by myself.

...However, the next day, I was ready to go to school. I went out and started my car. It started fine. Running fine. Sounded fine. I thought everything was fine. I went back in to wash up and do my business inside the house. When I got out, the car was dead. ... I tried cranking it and all I got was just a hiss, very weak crank. Then my roommate helped jumped the car and it came back to life. I thought maybe it was just one of those one time thing where the battery would die and be okay after a jump. *The battery was good, and was fully charged a few weeks ago from autozone.* I needed to go to autozone to have the battery checked and recharged.

Two blocks down, the lights started to dim and then completely out. by this time the car would just jerk a few times and then stalled on a turning lane. I got out and was looking around in the hood to see what I can make out of it...then a good fellow stopped and helped jumped it for me. So I made it through the 2 miles highway and when I came to a stop, the car did the same thing. I could see the lights going out, but the car was still running. But only for another block. As I was waiting for the red light to turn green, all I thought about was hoping the car doesn't die on me on this intersection. The car didn't die, but it jerked its way over a mile to autozone from there.

When I got there, and opened the hood to take out the battery, it smelt like something was burning. I couldn't tell if it's the timing belt, or was it the engine or was it something else. I took the battery in to check, and the battery was gone. I told the clerk about this scenario and he told me that it's the alternator that is not charging the battery. ...But everything was working fine before my cat fell... so I wouldn't think it's the alternator. I got the battery back fully recharged and the next day, the same thing happened. The battery was drained after letting my car warm up. except this time, it didn't come back to life.

I have read around for a bit, and I came to a couple assumptions but can't be for certain. one, that it might be the ecu, since it receives data from the o2 sensor. and now, I don't have the second sensor after the cat, perhaps that could somehow made my speedometer not work? two, that it could really be my alternator breaking and not charging my battery? i don't know what to think right now. I have just got the car out of the impound and just don't have enough for any new parts. I have heard people talking about the alternator fuse that the car will do similar things if it was blown. what if the fuse is still good? Help!.

indylude18

It sure sounds to me like it is your alternator. I'm not guessing the parts car you have has an alternator on it you could "borrow?"

Also, while you are poking around in the engine bay, make sure you are getting a good contact on both battery terminals and check your engine ground.

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Bluetop H23a Vtec Swapped NHBP '99 Base

f22man87

I've never had to replace the alternator on the prelude yet so I'm not sure on the placement of the wires, but by chance did the wiring from the alternator get cut or disconnected somewhere down the line? It could explain the burning smell you had if it grounded itself off at one point and it would also not allow the battery to charge back up.

Phantom240

I wouldn't think that the exhaust coming apart like that would have anything to do with alternator failure, nor would it come near any of the wires on the alternator. However, check the oxygen sensor harness to be sure that it did not short out on your exhaust anywhere. I just had to wire up a friend's CA18DET powered 240sx because his oxygen sensor shorted and melted the injector harness wires because they're in close proximity.

Other than that, I would say this is just a freak occurrence.

EDIT: For reference, the alternator wires run over the valve cover, and don't even come close to the exhaust. As to where they go from there, I haven't paid much attention.

spider0735

I haven't had the chance to take a look at my brother's car to see if he have an alternator available. The last time I've checked...while I was there taking out his exhaust assembly, his hood couldn't be opened. Of course, it could be frozen or something. but I will go over and take a look at it again to see if I can get it open.

and also, I didn't touch anything other than the exhausts... and the o2 sensor. so I don't understand why there would be any electrical wires being misgrounded on the alternator. but definitely will check that too.

there is one other thing that I touched. it's the screw on the manifold which holds a lose bar... that i had to losen it up to get it out of the way so I can pull the down pipe out. I have no idea what that little piece of metal is there for. and I don't think this has anything to do with the alternator?

just a question.... where is the alternator? I found two blocks that I found to the right of the engine that could be the alternator. the clerk at autozone told me that it shouldn't be difficult at all to take it out. but to me...i have no clue where to start. there's one on top which holds a belt, and the bottom one also holds a belt too. i was just so confused.

I cut the o2 sensor wires so close to the harness that I wouldn't believe it has any spare length to reach anywhere and get shorted. although, I didn't put black tape on the ends of the wires....so.... I will check that as well.

Phantom240

When you open the hood of the prelude, look toward the front of the engine (driver's side). The silver thing underneath the power steering pump is the alternator. From top to bottom, there's the power steering pump, then the alternator, then the a/c compressor at the bottom.

ExodusFX

The alternator looks like this:



It has vents in the casing and is the only one with a belt that also has wires connected to it. (The power steering pump above it has a belt & hoses)

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ExodusFX

By the way, this situation can be checked fairly easily if you have access to and know how to use a multimeter.

First make sure you've checked for any blown fuses and replace any that may be bad.

Do a voltage check on the battery with the car off. It should read at just about +12v. If it's 11v or lower, the battery needs to be charged or is bad. Do the test again with the car on. If the alternator is working, the voltage will read somewhere around +13v.

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