2000 Windstar Charging System

Hey everyone,

It's been a long time since I've posted, but I'm looking for answers to a perplexing problem. It's on my wife's 2000 Ford Windstar 3.8l.

Several months ago, I noticed that at idle, her charging light would occasionally turn on, and shortly turn back off. Assuming it was just a bad voltage regulator or alternator, I replaced it with one from a known good one I had that I salvaged from a 1999 model. It lasted for a few weeks with no lights and then the charging light reappeared.

I took it to the dealership (which I hate to do) and discussed the problem. They charged me $90 to tell me that it was nothing more than a bad voltage regulator.

I gave it the benefit of the doubt that since it was used, it died also. (Although, admittedly, this was a long shot.) This time, I purchased a brand new unit. No reman.

This one lasted around the same two weeks and the light reappeared. I started looking around in my Alldata account and saw that the alternator has a "smart charge" feature in which the PCM controls the windings currents and thus doesn't put too much load on the engine when it isn't needed.

I am not sure whether the PCM could cause the symptoms that I'm seeing. If you put a meter on it, you can see the voltage actually fluctuating between 11 volts up to around 15.5. Not rapidly, but you can definitely watch it move. I would think that the PCM modulating the winding currents would still maintain a constant voltage and you'd just have less current.

I have removed the brand new alternator and taken it to Autozone for testing. They tested it and told me that it was good. (which I suspected.)

Does anyone have any in depth info on the smart charge system? I'd also be interested in any additional theories as to what could be causing my problems.

Sincerely,

Mark

Mark -

I have an '00 Windstar - and have also seen strange charging system behavior.

I used the REMY support site http://starting-charging-help.com/ to get some help - and actually found someone familiar with the Windstar charging system. He sent me a wiring diagram, and some further info.

You can see the diagram here:

http://community.webshots.com/album/581090454uVJWHk

Following is some info he sent me on basic charging system checks - that includes a few details on the PCM-controlled aspects of the alternator:

==============================

Vehicle Running, under heavy load, and after a good drive cycle

Positive terminal of battery to B+ post on back of alternator (circuit 36 at connector c133)= <.5v and >0v ( IE; less than .5v but greater than 0v )

Positive terminal of battery to og/lb (circuit 35 at connector c123) = <.5v and >0v

Negative terminal of battery and housing of Alternator = <.5v and >0v

The PCM controls can be monitored by scan tool and/or oscilloscope for most accurate information, for generic rough indication the two circuits can be monitored for frequency and duty cycle, however there are no fixed specs. Roughly 100-125 Hz and a duty cycle that increases with load

=============================

If you're curious, here's the thread I started when first working on this problem:

http://www.automotiveforums.com/vbulletin/showthread.php?t=1063344

Loose connections ....and relays, relays, relays (.... YMMV)!

I've heard concerns about relays, too - and spent time removing relays to make sure connections were tight, etc. There are simply too many of them to start "hopeful" replacement. I'm not sure there's a good test for a marginal relay; hard failures are easier to track down. Does anyone know of specific relays that are common failure points for the Windstar?

I always use the voltmeter and a electric diagram. With the engine idling, first find the highest voltage ( to the hundredth of a volt ) coming from the alternator. Then start probing "everywhere" until you find the voltages that a just a few tenths of a volt lower .. Now you have a starting point. Note that all the small fuses have probe locations on their tops for using a voltmeter probe.

I have found so many elusive voltage drops that there is no hope to list them all. But I will tell of one vehicle that had prevailing voltage issues ... the problem turned out to be the bolt that was used for attaching the main ground cable to the engine. Some anti-sieze material was used on the threads that caused a 1/4 volt drop right at that location. Doesn't sound like much ... but removing, cleaning, regreasing the bolt made all the issues go away!