Let my start by saying that this past week I have woken up to a dead car two mornings. So I started to dig into the issue. I have replaced the battery already with a new optima red top, 60 dollars is not bad since it was under warranty. I also removed the alternator and had it tested. Autozone claims it is good.

The problem I am having is what appears to be variable charging. After running my volt meter on my car at the battery and alternator this is what I am seeing. The battery reads a constant voltage of around 14 volts. When I test the voltage at the alternator regardless of what I ground it on I see the same voltage as the battery, but I am also seeing dips. The voltage will dip from 14 down to as low as 5 and then come back up. It appears to be every couple of seconds this is happening. It is leading me to believe I need a new alternator or more specifically a new voltage regulator. So do my forum members agree with me or have some other ideas?

I should also add I have cleaned the grounds in the car and it did not make a difference to what I was seeing. The only other issue I have noticed recently is turning on the AC brings about a loud audio pop through my speakers. Not sure that is related, but that is why I cleaned the grounds.

 

I'm really surprised there are no codes with that type of fluctuation in voltage.

 

I have not even checked for any because the check engine light never came on. I might go look through the DIC tonight. It is a real split second dip and it does not even show on the DIC. I mainly see it on my voltmeter.

 

Sig

Try this:

Run a 10ga wire directly from the positive battery terminal to the BATT terminal on the back of the alternator (terminal under the balack boot). If the problem is resolved, you have a poor or loose connection on the starter solenoid. All the alternator terminals connect there.

Bill

 

Where exactly on the alternator are you measuring?

 

Bill I tried that using a jumper cable to make the connection. I was still seeing the dips show on my voltmeter.

I tested the connection from the alternator output bolt on the back and use both the alternator case and the driver's side frame as different grounds. I was still seeing the dip I mentioned.

 

A drop of 12 to 5 volts is huge. The amount of current draw to drop the voltage that far seems as though it would be welding something together. My point, I would question the meter or there is a major ground issue that is going open.

If you have your head lights on do you see them go out for this short blast to 5 volts or at least dim? I would even expect the car to quit running with a voltage that low.

 

....be nice to know if there are any codes to corroborate this......

 

I have not noticed any dimmer, but I have not really driven the car much since this started. What gets me is I only see that drop from the back of the alternator. When I run the voltmeter on the battery I see a pretty stead voltage.

As for the codes I will check tonight probably post up on that around 6:30 CST.

 

Hmmm...so I proposed you measure the voltage at the alternator using the negative battery post as ground. Sounds like you do not have a good ground where you are measuring at the alternator.

 

I will have to give that a shot. I have a few more things I was going to look at tonight when I get home.

 

If the alternator is properly connected to the battery,,,theres NO, ZERO, NADA way that the voltage output of the alternator is going to drop to 5 Volts unless your seeing a MAJOR load drop I.E. "SHORT"

Your seeing a steady 12+ VDC at the battery so, you should see a steady 12+ VDC on the back of the alternator. Its the same wire from the battery Pos terminal to the BATT terminal on the back of the alternator.

Either you have a poor connection of a bad meter. There are Two other red wires on the small plastic connector. Read them to ground and see what their reading. Read from the BACK of the alternator to a good chassie ground and then to the NEG terminal on the battery.

Bill

 

Bill,

I just got through with some testing. I also checked my meter against my truck battery and alternator. My truck has no fluctuations between it and I am confident in saying my meter is accurate.

I red the pink and red wires coming out the plug and see the same issue as I do reading from the alternator. I additionally, using jumper cables connected the battery positive and negative to the alternator and the housing. My readings at the alternator did not change. I have two videos if you can pm me your email that show what my meter is reading if you would like to see them.

 

What about connecting the red lead to the alternator, and the black to directly to the negative battery cable?

 

Heres the schematic for the generator:



Please post what voltages that you read on EACH wire with the engine running and engine OFF.

BC

 

Ok this is what I am seeing.

Engine off
Battery - 12.65
Alternator - 12.65
Red wire 1 (closest to engine) - 12.65
Red wire 2 (more pink closest to the tire) - 0.02

Engine on
Battery ~ 14.1 some fluctuation, but nothing more than about 0.05 V
Alternator ~ 14.1 with dips
Red wire 1 ~ 13.9 with dips
Red wire 2 ~ 13.9 with dips

Edit - I am not noticing any PCM codes since I replaced the battery. When my battery died I had the following codes:
U1255, B0851, B0503, B0508, B2483, B2587, B2592

 

What are you reading on pins C (grey) & B (Red) in the small connector?

 

I will have to go double check. From where I was standing the connector from Driver's side to passenger I saw pink, grey, red. I read what looked to be pink and then skipped the grey and read the red wire.

If you want to see what my voltmeter is showing on the alternator please see this video.

http://www.facebook.com/video/video.php?v=939353600925

 

Sig

Call me

PM Sent

 

By your video my bet is on your meter reading wrong. Cheaper meters don't filter for some of the pulses that can be present right at the alternator in the current. This can mess up with the meter reports. Can you borrow a good meter from a friend near by? Fluke would be a good thing...