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2004 Crown Vic charging problems


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Chipata
Novice

Oct 28, 2013, 7:35 AM

Post #1 of 12 (2257 views)
2004 Crown Vic charging problems Sign In

I have 2004 CVP with 195,000miles. Battery light started coming on and off randomly and the voltmeter would also drop. Following the leads on the site, I have changed the alternator and pigtail connector, belt tensioner, checked the fusible links, and all fuses are okay, no loose connections on instrument panel, the belt is only about 3 weeks old, and put a new battery ground. The battery is about 8 months old and once charged it keeps charge and cranks the car without any hesitation. Despite all this, the car will not charge unless it is given a high and abrupt rev. Gently raising engine speed does not get it to start charging. Once it starts charging it puts out about 13.6-13.8v and then the battery light comes on! The battery light initially comes with ignition, goes out when the car is started and the alternator is NOT charging. With the ignition off, I get the following readings at the pigtail connector
Pin#1: 0.7v
Pin #2: 12v
Pin#3: 12v
With ignition ON
Pin#1: 9v
Pin #2: 11.5
Pin#3: 11.5
What else could be the issue?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Oct 28, 2013, 7:50 AM

Post #2 of 12 (2253 views)
Re: 2004 Crown Vic charging problems Sign In

Did any of the symptoms change when you changed the alternator?



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Chipata
Novice

Oct 28, 2013, 8:00 AM

Post #3 of 12 (2245 views)
Re: 2004 Crown Vic charging problems Sign In

No changes after replacing alternator


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Oct 28, 2013, 8:24 AM

Post #4 of 12 (2242 views)
Re: 2004 Crown Vic charging problems Sign In

Have you tested for power at the main output terminal with the key off?



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Chipata
Novice

Oct 28, 2013, 9:21 AM

Post #5 of 12 (2235 views)
Re: 2004 Crown Vic charging problems Sign In

Ranges from 11.9 -12.5


Chipata
Novice

Oct 28, 2013, 9:26 AM

Post #6 of 12 (2233 views)
Re: 2004 Crown Vic charging problems Sign In

I don't know if it has any relevance/significance at all, but, I noticed that even with the headlight switch in the OFF position, each time I connect the battery, the headlights come on momentarily then go off.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Oct 28, 2013, 9:30 AM

Post #7 of 12 (2230 views)
Re: 2004 Crown Vic charging problems Sign In

Everything seems to be pointing to a bad PCM. That's what controls the charging rate.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Chipata
Novice

Oct 28, 2013, 9:40 AM

Post #8 of 12 (2228 views)
Re: 2004 Crown Vic charging problems Sign In

Any specific testing that can be done to give us a high degree of confidence in the PCM being the culprit?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Oct 28, 2013, 9:48 AM

Post #9 of 12 (2225 views)
Re: 2004 Crown Vic charging problems Sign In








~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Oct 28, 2013, 9:49 AM)


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Oct 28, 2013, 9:54 AM

Post #10 of 12 (2223 views)
Re: 2004 Crown Vic charging problems Sign In

High end scan tool to monitor the GEN COM circuit and to retrieve any charging system trouble codes. Also need a scope or graphing multimeter to monitor the GEN COM and GEM MON circuits to see what the signals look like. If PCM is commanding the alternator and you have no GEN COM signal going on, you have to think what PCM inputs are needed to make the alternator system function and test those accordingly. Once inputs are verified, you have good powers and grounds at PCM, and you have eliminated every other possibility that would keep the PCM from turning on the alternator is when you can have enough information and confidence to replace the PCM.

Also have ran into these reman cheap aftermarket alternators not working on these PCM commanded systems. Motorcraft or dealer OEM is the way to go.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Oct 28, 2013, 9:59 AM)


Chipata
Novice

Nov 10, 2013, 10:10 PM

Post #11 of 12 (2169 views)
Re: 2004 Crown Vic charging problems Sign In

Replaced PCM. PROBLEM Persists. Alternator still charges only when the engined is a hard abrupt revv. Battery light come son with ignition, goes off after engine is started BUT comes on when engine has been running for a couple of minutes. I am at my wits end


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Nov 11, 2013, 5:34 AM

Post #12 of 12 (2167 views)
Re: 2004 Crown Vic charging problems Sign In

What tests did you perform that led you to replacing the PCM?





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.






 
 
 






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