This is really bizarre - alternator

[woodysmom]

Ok guys, i JUST bought a new alternator and new battery. I installed everything back. now here's the problem.

When EVERYTHING is connected:
Voltage from battery reads 12.02 V
Voltage from alternator reads 11.53 V

When I disconnect the Wires from the alternator (positive wire)
Voltage from battery - same
Voltage from alternator - 0.54 V

Now can someone explain to me WTF is going on? Just yesterday, i posted claiming the alternator was pushing 5V. It was then i thought that the voltage regulator might be bad...but isn't the voltage regulator on the alternator?(i just got a brand new alternator).

This is really baffling, the only thing i can think of is that a positive is ground or vice versa. The alternator DEFINETLY works because i had it bench tested before i brought it back.

Anyone please help!

[DuffMan]

I'm pretty sure that our alts are interally regulated.

It sounds like your alt is bad.

[woodysmom]

ihad it bench tested and it's good...remember its brand spankin new!

[thx247]

the alternator is internally modulated by a diode array.

So the alt was bench tested....um.

I know little about electricity...bad ground? /me guessing

[misnomer]

This may be a stupid question, but was the car running when you checked these voltage values?

[woodysmom]

yea it was runnning heheh

[RedSuns]

do you have to jump the car off to start it or keep it running...or will it stay running all day long....


I had a similiar problem where one of my engine grounds were disconnected. the car had to be jumped to start but it would run fine once i got it started.try checking you 75 amp fuse.

[woodysmom]

Is there a diagram of where the grounds for the engine are located?

Thanks!

[Bill Roberts]

replace the battery cables. You could have some corrosion keeping them from conducting properly in the cable itself. Clean the ground on the block.

[FliMSiCaL]

with the engine running your voltage at the battery should read from 13.8 volts to 14.2 volts to indicate a properly functioning alternator. Start your engine, rev it up to over 4300 rpm's and take a reading, if its right, you have a loost/shorted alternator signal wire.

I went thru all of this 3 weeks ago.....pain in the @$$.

[RedSuns]

Originally posted by woodysmom
Is there a diagram of where the grounds for the engine are located?

Thanks!

the FSM shows you everything that is grounded but trying to track them all down is tough...just crwal over every inch of your car to see if you can track down the fault

[woodysmom]

ok guys. On elast question.

My battery is re-located to the trunk of my car and is ONLY grounded to the chasis in the trunk. Could this cause a problem? Should i run a wire to the engine bay?

Thansk!

[woodysmom]

K guys,

I am still having my alternator problem

lemme update you on what i've done

i reground my alternator/block/distributor. Checked all the fuses and had my alternator bench tested again. Lemme restate the problem

When alernaotr is plugged in;
voltage output from battery = 11.9
voltage output from alternator = 11.8

When alternator not plugged in
voltage output from battery = 11.9
voltage output from alternator = 5.9

I think that when i rev the engine the voltage goes up, but i'm alone and can't confirm this, but i'm pretty sure it does.

My battery is located on the back of the car and is ground to the bottom of the trunk.

Any advice would be great!

thanks

[woodysmom]

bump for desperation

[Muzzy]

ok..try this...start the car...disconnect the neg battery terminal..if it still runs the alt is ok....if not its crap or not hooke up well(maybe)

[woodysmom]

Hey muzzy,

Thanks for the tip. Just tried it and my car died immediately. Now, this is a BRAND NEW alternator. Bench Tested and working. Where could it possible be not hooked up well?!

Thanks

[Muzzy]

the plug on the left side of the alternator (when facing it from the wheel of alt) and the one on the back of the alternator

try them

[FliMSiCaL]

try running a 2nd LARGE ground wire from battery to engine block, leaving the trunk one in place, see if that helps.

[old_s13]

Rev the motor from inside the engine bay by pushing on the throttle body.

Check the output from the alternator TO the battery with a multimeter, at higher RPMs it should be over 13v.. topping at about 14V. If it doesnt do that, you have issues with your electrical/charging system.

- Mike