New Battery and Alternator - Battery Light Still On

[blackf0rk]

I'll preface my current situation: Battery light came on last week Thursday. Checked out the battery and alternator and replaced them both yesterday. I'm getting 14+V at the battery; before the replacement is was 11-12v. Now though, same as before, the battery light comes on about 20-30 seconds after I turn on the car. I went to AutoZone and had them scan my codes and there were none. My current research on this has been this...

I read through this thread, which didn't lead me to much:
http://www.mercurymarauder.net/forum...=Battery+Light

I then read through this thread:
http://www.mercurymarauder.net/forum...=Battery+Light

According to this last thread, if I unplug the alternator 3-prong plug, rev the engine at 4,500RPM for 3 seconds...my battery light will go off. Is this correct?

I'm not sure what to do as there are no codes and everything's new...

[Local Boy]

Regulator? I think anything over 14V is high.

[FordNut]

First, where did you get the replacement alternator? Check to see that the regulator is the same as the one on the old alternator. I have experienced battery light and charging issues when installing a Cobra alternator, which looks the same but is not functionally the same.

Second, check the wiring extensions for the alternator. I have heard of some Trilogy owners having charging issues due to bad connections at the extension harness.

[blackf0rk]

First, where did you get the replacement alternator? Check to see that the regulator is the same as the one on the old alternator.

1. You don't even want to know what it took to get this alternator.
2. How do I check to see if they're the same or different
3. If I'm getting consistent 14V would it really be the regulator?

[FordNut]

1. You don't even want to know what it took to get this alternator.
2. How do I check to see if they're the same or different
3. If I'm getting consistent 14V would it really be the regulator?

I put a Cobra alternator on my MM once and it went to 15v immediately on startup and stayed there. Just a few minutes/seconds later the battery light would come on.

I have heard, but can't confirm, that the wiring connector for the regulator is a different color.

My guess is that the old alternator may be ok, but the wiring connections for the Trilogy extension harness have corroded or broken. Then replacing the alternator with one which is not compatible with the PCM-controlled regulator introduced a second problem.

[blackf0rk]

Well here's the story.

I order the alternator from AutoZone, but they had to order it. By the third day of waiting and still not even a tracking number, I cancled and went to AdvancedAuto. They didn't have it either, but could order it and have it in by the afternoon. I said ok. When it came in, and I compared them, they were completely different. I took the new (and wrong) alternator back with my old one and showed them it. The guy looked at some numbers on the alternator and they had the one I needed in stock. He said he found it off a Mountaineer.

It's not putting out 15V. When I say 14+, I mean 14.1 to 14.5 at peak. But nothing over that.

[SamF]

All I can say is I went thru 2 alternators (represented to be replacement equals) one physically would not fit, I didnt even take it from the store, the other looked exactly the same as mine but exhibited the same symptoms you have, throwing just over 15V and triggering the BAT light after about 15 seconds. I went to Ford for a new Alt and its running fine now...

[FordNut]

FYI, I recently bought one of the ebay 200A alternators and it's working just fine. Cost $241 including shipping. Already has the non-clutched pulley so it should be a quick & easy bolt-on for a Trilogy.

[JMan]

Quit playing!

http://www.motorcraft.com/wheretobuy.do

J

[blackf0rk]

...exhibited the same symptoms you have, throwing just over 15V and triggering the BAT light after about 15 seconds...

Ok, but mine isn't putting out 15V...

[SamF]

Ok, but mine isn't putting out 15V...

I dont know enough about it one way or another,my new one is putting out just under 15v. All I know it was a nightmare getting the right ALT and if I had to do it again I would go directly to Ford. NAPA and the other places I called didnt even have a direct cross reference replacement to the FoMoCo part number. It was "oh yea...I can order it, Mercury 97 and up are all the same" which is not the case.

I had mine in and out about 5 times (attempted to rebuild it once at a local shop, that effort failed miserably)

Call Ford

[blackf0rk]

I'm getting a cool and consistent 14.5v on the battery...

[magindat]

Quit playing!

http://www.motorcraft.com/wheretobuy.do

J

Go to Jake's link. Click product look up on top, then buyer's guide on the right. Type in the stock MC part num and see what comes up as a reverse cross reference.

[FordNut]

Anybody around your neighborhood got a Marauder? Put the new alternator on it and I'll bet you get the same problem. Too many of us have been down the aftermarket alternator road with the exact same indications you have described.

Or just get some black tape and cover up the lamp on the instrument panel, as you said it's putting out good voltage.

[Badger]

I updated the second thread on your original post.
If you have a bad connection/splice your PCM will increase the field to your alternator to attempt to charge the battery. That may be causing your voltage to go high.
My tech finally found the bad splice by hooking up his volt meter and going over the alternator wire inch by inch. When he got to the crimp all it took was a little twist to get the connection to open.
Of course I do recall the smell of the burning plastic of the crimp but I had assumed that the smell was the blower pulley "burning in" the underhood insulation and nothing more.