check charging system - frustrating issue

[DSNY]

New member here so I will head over to the Intro topic and say "hello"...but
If anyone can help with this I would be grateful.

2003 Expo, EB edition 4.5L

Work done at garage I have used for over 5 years.

2 months ago: Alternator replaced & Harness (not Ford Alternator)

2 weeks ago, check charging system warning on at every start resulting in flat battery.

He kept for 2 days trying various options, replaced harness. Ended up fitting another Alternator.

The very next day on cold start, check charging system light warning was back BUT it would go away once engine was revved (or driven)
Warning did not come back during day of restarting.

He had it back last week and said he ended up replacing one of the battery cables.

The 1st cold start the next day I got the exact same warning, which went off once I revved the car.

At one point he did suggest it could be the PCM - but as they are $1500 to replace I'm not taking that route unless he can prove it is. Everything I read points to alternator but I'm wondering if the specifics of the issue give any more pointers to anyone with it just happening on a cold start?

Any help really appreciated

 

[Bedrck47]

Check you voltage at the battery with the engine off and the key out.

Check you voltage at the battery with the engine running at idle and again at 1500 RPM's

Check the voltage at the alternator stud as above and at 1500 RPM's

Post all results

 

[stamp11127]

2 months ago: Alternator replaced & Harness (not Ford Alternator)

2 weeks ago, check charging system warning on at every start resulting in flat battery.

He kept for 2 days trying various options, replaced harness. Ended up fitting another Alternator.

At one point he did suggest it could be the PCM - but as they are $1500 to replace I'm not taking that route unless he can prove it is. Everything I read points to alternator but I'm wondering if the specifics of the issue give any more pointers to anyone with it just happening on a cold start?

Why is the harness being changed?
Why is your mechanic trying various options? Seems cause of the problem hasn't been determined and/or he doesn't know what he is doing.
Suggests it could be the PCM? What data does he have to back that statement up?

You need to provide the test results from bedrck47's reply in order to troubleshoot the problem.

 

[Skauber]

And a new PCM is not 1500 bucks, you can find a used for a lot less on ebay or in your local junkyard. Just make sure the partnumber matches, and you're good. Have to get it reprogrammed though, but I can't imagine that the dealer will charge too much for that. It doesn't take that long.

 

[DSNY]

Thanks fr all the replies. I was going to say I woud have to go get myself a multi-meter to post the results of tests as above but today things took a new twist.
After a couple of days of cold starts in which the warning did NOT come back (go figure), my wife headed off to visit a friend and 20 mins into her trip, the warning came on and has stayed on so she may well have a flat battery by the time she gets there.
The garage again is suspecting the PCM and although I did say he hasnt really got any test results to prove that he is saying "the PCM is controlling the charge and as we've replaced the Alt it seems the next logical thing to look at.
I have asked him to fit a Ford Alt, which he has agreed to do, because everything I have read with people describing this problem, the blame has been put on non Ford replacements.

 

[Bedrck47]

Not trying to be a smartass which I normally am

But being you are paying good money to have your garage throw parts into it Ask then to give you answers to what I posted above.

Have them use a volt meter and get those SIX voltage readings before they replace any parts or the pcm

Then come back on the forum with those results and get some GOOD FREE ADVICE.

How old is the battery???
How many time during all of the above have you run the battery down???

 

[DSNY]

The battery was new in December. The original 'check charging' fault happened in June (the battery went flat) and the Alt & Harness was replaced. Two weeks ago all these issues started again (when wife was out on a trip), warning came back on and battery was flat when she got back.

He hasn't charged me a penny extra for fitting the 2nd Alt and the trip back to him last week

I did ask him if this could be related to the battery and he said the battery checks out fine.

I'm kinda stuck not wanting to offend him by making out I know more than him, because I don't. I'm not a mechanic....BUT...as I said, everything I read points to fitting a Ford Alt so at least he's gonna do that.

I haven't read anything anywhere that this issue is a PCM problem.

As he cant take it in until Thurs I may run out and get a decent Mutli-meter so I can post the test results

 

[Bedrck47]

I just had to replace the Alt in my expy as I was stranded and near a Autozone store The alt that I got was a rebuilt alt and have not had any issues due ti it not being a Ford Alt. Not saying that isn't your problem but It would be very helpful to know the voltages.

You can get a decent meter at lowes or homedepot. Just make sure you have it on the correct scale and set for DC volts when you use it

Although you "haven't read anything anywhere that this issue is a PCM problem" the PCM is part of the charging circuit.

Update:
Need to clarify my above statement "the PCM is part of the charging circuit" This statement DOES NOT apply to any of the 1ST gen expeditions.

 

[Bedrck47]

There are a few here on the forum that do not believe in just throwing parts until the problem is resolved

The best way to troubleshoot a problem is to start at the beginning and work your way to the end. Just thinking that a certain problem was solved one way doesn't mean that is always the answer to the next time the same problem occurs

 

[DSNY]

Yep I appreciate that not all 'non Ford' Alt can be bad.

I'll run out this afternoon and get a meter although I suspect I'll have to charge the battery when wife gets back because she'll prob run into the garage and turn it off LOL

I don't mind replacing the PCM if it can be proved it's the problem. Although if it is, it's gonna make me wonder if that has always been the problem and I didn't need a new Alt 2 months ago

These elctrical problems seem to be a ***** to figure out

I appreciate the help