Just replaced the alternator. Getting same results.

The scan gauge II volt reading and a hand held DMM read any where from 11.6 to 12.6 at idle. Goes up to 13.0 at 1500 RPM. By accident, I found that the I get the same readings with the alt plug ( not red wire) disconnected.

What signal comes into this plug and where might it come from? What is this plug for basically??

I did have a bad battery that was replaced yesterday.

Thanks

Edit: 03 Ex still stock.

 

Bet you got a bad alternator.

(do you have battery voltage on the red wire at the alt?)

 

Well the old alternator just checked good at Autozone. I got the repalcement from DB Electric with print out of its testing.

I really thought I had a bad alternator at first too. hence the waste of money now.

 

The PCM controls the alt. make sure the conector is clean, and check to wireing.

 

I have had AZ tell me an alt. was good and it wasn't. They have also told me my batteries were good and they died 6 days later. They don't have what I consider certified techs. You get what you are paying for. They are a good general source but nothing to take to the bank.

 

I believe this is only true with dual alternators. For single alternators, the PCM is not "involved".

 

We need to do a little more homework here. I thought the pcm controlled both single and dual alts. Do we have any techs on line to clarify this?

 

Here you go, pulled directly from the workshop manual:

The generator is belt-driven by the engine accessory drive system.
With the ignition key in the ON position (single generator system only), voltage is applied through the warning indicator I circuit to the voltage regulator. This turns the regulator on, allowing current to flow from battery sense A circuit to the generator field coil. The dual generator system (with the ignition key in the ON position) applies voltage through the powertrain control module (PCM)-controlled I circuits (1183 [WH/YE], upper generator; 1185 [YE], lower generator) to both generators. Once the PCM sees a voltage drop on the lower generator, it turns off the voltage to the lower generator if the glow plug system is cycling. Once the glow plug system stops cycling, the PCM applies voltage to the lower generator, which turns the regulator on allowing current to flow from the battery sense A circuit to the generator field coil; at which time it begins to function normally. The PCM maintains voltage (on the I circuit) to the upper generator at all times (key ON, engine off or running). This turns the upper generator regulator on, allowing current to flow from the battery sense A circuit to the generator field coil. When the engine is started, the generator begins to generate alternating current (AC) which is converted to direct current (DC) internally. This current is then supplied to the vehicle's electrical system through the output terminal (B+) of the generator.
Once the generator begins generating current, a voltage signal is taken from the generator stator and fed back to the regulator S circuit. This voltage feedback signal (typically half battery voltage) is used to turn off the warning indicator on the single generator system while on the dual generator system, the PCM uses this signal to determine when to turn off the warning indicator.
With the system functioning normally, the generator output current is determined by the voltage of the A circuit. This A circuit voltage (battery sense circuit) is compared to a set voltage internal to the regulator, and the regulator controls the generator field current to maintain correct generator output.

 

Can I assume then that on a single alt. system that the voltage reg. is built into the alt. and on the dual system that is controlled by the pcm?

 

on a single alt system the alternator is not controlled by the pcm. in a dual alt system, the second alt is turned on by the pcm when it is needed. to answer the origional question, when checking an alternator on a single unit system you need to verify that you have battery voltage at the positive term. of the alternator as well at the orange wire ( or yellow in some cases ) and 12V key on at the green with red tracer wire at the alternator plug. If all these check out and you have no amperage or low amperage and voltage after 2 minuites of running, you have a bad alternator.
Hope this helps. Larry

 

Thanks toolman, you have cleared my head till I have another beer. By the way, I gave u a rep for this. 1st time it was explained in simple terms.

 

My pleasure LMAO

 

I think you doubted me ........

Great posts jboczar and toolman05kr!

 

Maybe my beer is stronger than your hydrocodone?? lol

 

God, those complicated words are making my brain hurt. LOL