Darthg

I searched all day and didnt find anything that fit this.

Three days ago I was rollin along and my Batt light pops on. No big, I get in to work and slap a fluke on it. Battery is a touch low but still strong enough to start the car. (11.7 - 12.00) Restart and check the charge of the alternator its in the window at 14+, I figure ok it was a fluke and the light wasn't on anymore.

After work just as I was rolling home the light came on again and I was at an intersection with an auto parts store. PERFECT I said. I pulled in and left it running and tested the circuit again. ahhhh 11.1 now the alternator is not charging!! I figured how easy could this be and me in the right parking lot!!

I order the alternator (400 bones might I add!!!!) two days wait and I figure Ill roll on home its not that far and my luck was up. I made it home stuck the battery on charge for the night on maintenance free charger and away in the morning. Another day luck holding I made it to work and the light was off for the first half of the trip came on for the second half. (brought the charger to work) Charged up and home away.... All seemed well. Only car and no other source for the part I have to push this.... (Oh yah just tagged up 50,000 miles and the warranty is out.)

I didn't make it home that day.... car sat overnight in a nice lady's driveway. Light stayed on the whole way to dead. When the other dash lights started coming on I knew the systems where shutting down because the battery was about to die.
Waited one more day and I get someone to pick up the alternator and meet me at the car. I had the tools and swapped it out in about 45 mins. (minus one of those blasted plastic **** that the hose goes to..... Ill cover that later... )

New alternator in only one day of work lost... No big deal. and I was off and no light... I won. I was so happy! The dealer didn't get to gouge me again!!!!!

It was not meant to be. Just as I was getting to the drive way home the Batt light popped on and the string of curses was colorful I promise! The battery is ok off and the alternator stopped charging again. I cut it off and try after a few hours and it is charging again. then the light will chop on and no charge.

Please I cant loose too much more work hit me with ideas. Here is the list of what I have done:

Checked all fuses**
Charged and tested the battery
Replaced the alternator
Checked the connections to the battery
Checked the connections to the alternator
Checked the connections to the fuse panel under the hood


** I forgot to mention the first time the batt light came on I noticed the cigarette lighter was not working... the time I pulled into the auto parts store I traced the fuse and it was out. I replaced on the spot and it Fixed the cigg lighter but didn't fix the problem with the alternator. The fuse hasn't burned out since but that is the least of my problems....

-Desperate to make it to work on Mon.

EDZRIDE

iTrader: (1)

What was the charging rate of the "new" alternator?

Mazurfer

You got an aftermarket stereo?
Have you put a meter on it when the car is running and when it's off?

Darthg

2004 all stock or dealer parts. New alternator when light doesnt come on yet is 14.7. When I wait and let it idle for 5 mins the light comes on and Im reading battery only voltage. 12.+ and dropping.
Car off is simply the battery voltage and I didnt notice a significant drain.... Notthat that was a problem.

Mazurfer

Slightly confused. So when you start is it's about 14.7(a tad high, but okay), and you are measuring this at the battery terminals....................then without moving the meter leads at all......after 5 minutes of idle, you see it as 12v and dropping? If this is true..........and i want to be careful here, but if you read 14+(after starting) and on the battery terminals, but then see it drop, then I think the battery might have a dead cell or two and is dragging down the alternator. You have another battery you can try or have this one checked out? What if you started the car and then removed the positive lead of the battery(carefully without letting it short anywhere) and measure at the terminal you took off..........what do you see there after 5 minutes?

G3tR3DDY2GR3DDY

iTrader: (8)

i have this same exact issue, it sucks

both my battery and alternator were bad. fortunately i have a few alternators and my battery was still under warranty.

I would recommend getting both, but first i would recommend taking that 400 dollar broken alternator back to auto store and buying a good used from someone like me or mazmart for wayyyyy less, then getting a new battery.

The fuse blew because the alternator is trying to overcharge the failing battery while the car is running. It sees the bad cell draining significantly so works harder to output stable running voltage, but then also puts too much current to power systems in the car. Your cigaretter lighters will either run like a banshee or pop a fuse.

Mazurfer

yep, sure seems like that's it Patrick........hopefully he will get that battery checked out. Seems like the alternator might still be good.....but need to have it checked as well.

dannobre

iTrader: (3)

Check the connector that goes to the alternator from the wiring harness. The alternator charging is controlled by the PCM....poor signal = no charge

Darthg

Ok I made a video with my iphone and you can see it disconnected and running. You can see the charge and hear what I hear. I had the wife bring up the RPMS and when she let off it died of its own accord. This would be when the batt light would come on and stay on.

www.darthg.com/RX8-1.mov
Sorry its 31.2 MB

Darthg

If it wasn't on the alternator right from before I changed it it was on good when I put on the new one. Where is the other end?

I cant exactly load test it here at home but the charger is pretty good and this battery is less then a year old. Also given the last result I would say the battery has nothing to do with it.

Cuts out... mabey another leg in the system.... I am an older school mechanic and can admit that this car is out of my basic skill set. I wish the manual could be gotten without paying SO MUCH!

dannobre

iTrader: (3)

There is an online manual that has a lot of info in it..

You might want to find a wiring dia and check the wire to the ECU...to see if it is giving the correct control signal

Darthg

Where?

dannobre

iTrader: (3)

try here...BTW..this is from a sticky in the Tech section...might want to have a look at them


http://foxed.ca/rx7manual/2003mazdarx8/

Darthg

Yah I found this before you got back to me. It is very vague and doesn't have a trouble shooting for electrical at all.

Still in trouble for tomorrow.

ken-x8

Try this one

http://www.hi-impact.org/ryang/modif...8_manuals.html

Darthg

Wow I just got done pouring over the electrical section and tracing the circuit out and found the PCM in the loop. I decided to look into the paperwork of the alternator I got and it has a service bulletin with it now the question raised of:
If the alternator is designed to be regulated by the PCM, could there be a problem in there that would be an easy test?

When I was coming back I saw the new post for the manuals I had found. Thanks tho!

G3tR3DDY2GR3DDY

iTrader: (8)

i see iphone case on car :P

the idling voltage you have is fine and its at 14.4 while driving (revving) so thats normal

i would say its something else causing the issue than the alternator or battery, but still go swap that 400 dollar one back, thats way to much for a stock alternator.

i will sell you a PCM and good alternator for less than that.

Darthg

Id Love to save the money on whatever part it is that I need but I think I should try to figue out what the problem is first. I have a bad feeling that whatever it is it is killing the alternators. So useing the retail stores ability to swollow that cost is to my advantage. Ill return this one and get another. If that doesnt work there is no way three are bad.

Darthg

Ok, the worst has arrived.... In having it towed to the dealer. Im thinking its the PCM is the roblem and live in BFE so used parts are a little slow to get to me.
Ill let you all know what the problem was.

Darthg

Dealer said they just replaced the alternator because the old was bad. Must have been a bad voltage regulator on the second one.