RX7Club.com - Mazda RX7 Forum

RX7Club.com - Mazda RX7 Forum (https://www.rx7club.com/)
-   2nd Generation Specific (1986-1992) (https://www.rx7club.com/2nd-generation-specific-1986-1992-17/)
-   -   Electrical problem (https://www.rx7club.com/2nd-generation-specific-1986-1992-17/electrical-problem-861023/)

86NA7XR Sep 2, 2009 05:58 PM

Electrical problem
 
Ok long story short, my alternator went bad. I got a new one, installed it, and now im getting no power with the key on besides the door open idiot light, no headlights, wiper, hazards, air, etc. Checking the system my main fuse was blown and is getting a tremendous amount of current, sparking every time i put my dmm up to it, and heating my lead wires while doing so.. I tried looking at the factory service manual for a wiring diagram or something. The small wire on the negative side is the one holding all of the current, Does anyone know what that wire leads to? and to add my rear wiper does not work. im thinking it may be shorted out resulting in this situation but i need to know where the one small wire at the negative battery terminal leads to for me to find out. your help is GREATLY appreciated. I've only had this car for about a month maybe and its not treating me too well.

RotaryRocket88 Sep 2, 2009 06:00 PM

Are you battery cables hooked up to the correct terminals? Doing it backwards will pop the main fuse.

86NA7XR Sep 2, 2009 06:09 PM

they were on the right terminals, double checked myself freaking out. That was the first thing i thought of.

calpatriot Sep 2, 2009 06:37 PM

SUre sounds like a dead short to me. Are you saying the system is pulling high current even when the main fuse is burned out?

That doesn't make sense... unless the short is between the battery + terminal and the main fuse, but that is a very short run.

What happens if you pull all the fuses in the car except the main? Do you still get the high current?

HAILERS Sep 2, 2009 07:22 PM

The positive cable on the battery has two cables. One large, the other smaller.

ON all three of my cars, the negative cable has but one cable.

The small wire on the POSITIVE cable , goes to the fwd side of the engine bay fuse box and feeds those fuses in that box plus the Main Fuse which in turn feeds the single black wire that goes to the ignition key. That wire has batt voltage all day long as long as the Main fuse is good and the right battery cables are installed on the correct battery posts.

That single black wire at the ignition switch, feeds most of the fuses in the interior fuse box IF the key is put to ON.

BAtt cables are on ass backwards imho. Just an opinion, nothing more or less.

misterstyx69 Sep 2, 2009 07:56 PM

Negative wire has the STRIPE on it.
do yourself a favor and get some RED and black tape,and mark the Cables...It happens to everyone,at some point.

86NA7XR Sep 3, 2009 01:09 AM

Yea that just happened to me, thanks for the help.
One more question now that we're on electrical and i already feel like an idiot.
There is a connector behind the alternator that looks like it should plug into the back of the alternator itself. I looked on the fsm and it shows it connecting but it also shows the wire coming from somewhere else. Not to mention it wasn't plugged in when i bought the car.

Once again thank you tons for the help!!

AGreen Sep 3, 2009 03:47 PM

Haha... that's the field connector for the alternator. Picture this:
Your alternator works on the principle that magnets spinning around a bunch of conductors induce a voltage. Well, the armature of the alternator is not a permanent magnet, it's an electromagnet. Without the connector plugged in, it's not going to get the voltage to the alternator to make the magnetic field to make electricity. Yes, it takes electricity to make it.

So... your alternator may not have been bad.

HAILERS Sep 3, 2009 03:54 PM

The alternator plug on a seires four has a BLACK/WHITE and a White/Black wire(s).

86NA7XR Sep 5, 2009 10:31 PM

awesome, so could that have made the old alternator go bad though, cause it was not plugged in before.

HAILERS Sep 6, 2009 03:27 AM

The voltage to the alternator from the WHITE/BLACK wire is what excites the alternators regulator. The BLACK/WHITE powers the regulator inside the alternator.

A RX alternator can self excite if the WHITE/BLACK wire is missing thru residual magnatism in the ROTOR of the alternator. Usually you have to rev the engine up a bit to make it self excite.

Once excited, and no power to the regulator inside the alternator, I can see how the old alternator might have destroyed itself over a period of time. Just an opinion.

86NA7XR Sep 6, 2009 04:02 AM

Thats what i was thinking!!! So plugging it in excites the alternator, not stressing it, or causing the long term harm. I'm gonna plug it up.


All times are GMT -5. The time now is 08:35 AM.


© 2026 MH Sub I, LLC dba Internet Brands