Having electrical issues, im a n00b with electrics so any help would be greatly appreciated.

11.18v at the alternator with the car running, jumps back to about 12.3v with the car off.
11.25v at the battery with the car running, jumps back to 12.3v with the car off.
changed the battery - no luck
changed the alternator - no luck
double and tripled checked all the ECU pinouts, there is only one that is for the alternator, its the right pin - no luck
double and triple checked every fuse in the engine bay and interior - all fine
double checked and triple checked the harness coming off the alternator, no shorts and all fine.

Took it for a little drive but didn't take long before the rev gauge started going haywire and the SRS and ABS lights coming on.

Tried to start it but obviously no juice the battery so jumped it and with the leads connected to a good car it sees 13.8ishV at the battery and alternator and everything works sweet, disconnect a lead and it drops back to 11.18v

Where should the + cable run to off the alternator? just to check my wiring is all good.

 

Just had a thought, today the rev gauge was going crazy but the car was driving fine, also the ABS and SRS lights come on and off at random. Would low voltage cause this or is it a cluster fault, also if its a cluster fault and the batt light is not coming on would this cause the alternator not to charge on a evo5?

And If I was to get a new cluster would the kms match via ECU or is it saved in the dash (digital display) so I would be stuck with what ever kms the cluster is?

 

Steve,

Did you digger out what the problem was? I'm having close to the same problems with my evo 7.
I ordered a ecu to see if the problem is in the Ecu not telling the altonator to charge the battery. I will let u know what I find this weekend.

 

Whatever the KM the cluster is your stuck with however if you drive around without the dash plugged in the alternator wont charge the battery.

 

I'm pretty sure you got a short circuit somewhere.


You should definitely check all positive cables and make sure they are not touching anything that is ground, which is the whole damn chassis and everything metal bolted to it including the engine.


You should not be reading lower than 12V at any point, and it should definitely be about 14.4V cold and 13.6 or 13.8 when hot coming from alternator. Since you already replaced the alternator and battery, check all wiring, and don't leave the battery connected for long until you find the short, it is likely draining your brand new battery and making it turn old real fast by discharging it.

edit: I saw that you said you checked for shorts, but around the alternator, did you check the starter? how about the main fusebox next to the battery? Are you measuring amps while you check for shorts? Or just doing visual checks?

 

edit: your short seems to only be happening with the ignition on yes? I suspect it may be your starter positive wire, maybe it got messed up on a clutch job or whatever, but it might be rubbing on your tranny or chassis with bare wire exposed. But I would say your alternator and battery wiring are sound because they are always connected even when ignition is off. Something that turns on with the ignition is shorting, I'm pretty sure of that. Check ignition system wires and everything that connects to your fusebox too. But if it's causing a big short it's probably a big wire.

 

I changed out the ecu that was not the issue when the car is running the battery amps are dropping one amp every 30 sec and with the a/c on they drop even faster. I wonder if it's that little silver amp looking box that's on the firewall of the engine-bay? I think that's the relay for the altonator.

 

Tomorrow we are gonna take apart the dash and see if it's one of the wires back there or the Gage's. But I'm sure it's something that talks to the ecu and alternator. So my money is on the voltage regulator!

 

Is the voltage regulator replaceable or do you have to get a whole new alternator? I'm having odd issues with voltage also. It will read 13.7 then drop to 11volts. It's very random and if I'm on the highway it will drop to 11 volts and the AC will shut off but the. If I take it out of gear and let it idle for a few seconds while cruising it will go back to 13.7/14 volts. Very random and intermittent.

 

The voltage regulator is built into the alternator and you can replace The voltage regulator but the brushes inside the alternator need to have a small *** howl thru them so if u push them down with your finger u stick the smallest Allen key in the hole in the back of the alternator and thru the brushes and they will stay down so u can put the alternator back together

 

Now I'm 99.9% sure it's the alternator or the voltage regulator inside the alternator so I ordered a black advanced alternator from japan I will replace the old one with the new alternator and lit you know if that fixed it. Fingers crossed guys. It's been about a month from the last time I drove the car.

 

It's just odd because this all began after I had the clutch job. It's an intermittent voltage issue going from almost 14volts down to about 10-11 volts. It's easy to tell because the AC fan speed drops and the qc stops working and blows warm air then if I roll at idle for a bit it jumps back up and the fan speed goes up and the air gets cold again


Not sure where to begin diagnosing this

 

You need to replace your alternator I just got a new black alternator it's a really good company but the are expincive but worth it they are mad to put in race cars with high RPMs I should get it this week and I will put it in and let you know if it worked but if you go to want to spend a lot of money just order the alternator regulator and brushes and rebuild it yourself it is so easy there is a video on YouTube that will show you how to take it apart it's just 4 bolts