batterly light blinking / all lights pulsing

[neilzonwheelz]

This is my first post, but have been using this forum for quite awhile to gather info/insight into a misfire problem I was having. Long story short, I replaced all spark plugs...using 3 motorcraft and 5 autolite plugs (due to store inventory), but was still having "rough idle/bucking while driving issues". Decided to pull out autolites and put in motorcraft, and all is right with the world. At least for a few hours. Then my battery light came on, and now it's blinking...and all my interior and exterior lights are pulsing while at idle. As the lights pulse, I can hear my engine dip in rpms in sync w/ the pulsing lights.

I've got a 2000 4.6L Expedition w/ 146K miles...and 1yr old battery. I don't know how old the alternator is. I've been disconnecting the neg terminal on the battery somewhat frequently over the past weeks as I've been working on the spark plug issue. I've checked the battery connections and they look good. I checked fuse #11 (alternator field) and it looked good. I checked a few ground wires attached to the chassis (passenger side near firewall) and the wires running to/from the alternator and they look good as well.

Any other things I could look at? I know I can go to Autozone and have them test the battery and alternator voltage, but was hoping to investigate all other possibilities before that. It's just odd to me that this issue came up right after working on the spark plugs.

Thanks in advance!

 

[rtbrjason]

I'm not sure what the issue is, but I too am seeing all light pulsing a little at idle and they seem to pulse a bit faster when RPMs rise. I am not getting the flashing battery light though. At this point I've put in a new battery, new ground wires from the battery to the body and block and have tried 2 alternators.

I started a thread on this and the consensus was that the alternator was causing the issue. I may try a 3rd alternator of a different brand, or I may look into all the wiring and connections once it warms up a bit. My guess in your case would be to look at the alternator.

 

[bedrck46]

do an alternator load test to see what voltage the alternator is putting out

 

[splintrcel]

My buddy worked at advance auto and he said if you bought the rebuilt alternators some would fail within a few days. Dont cheap out on the alternator. I would make sure to try out the nicer $200 one because if you still get the issue you know its not that.

 

[neilzonwheelz]

**fixed**

So I decided to go ahead and buy a new alternator from Autozone and install it last night. The install was a breeze compared to the knuckle bloodying spark plug installs. Once the new alternator was installed, I start the car up...and everything was still pulsing. Worse this time. Fed up, I decided to drive to Autozone in the Expedition (a few cars pulled over as my headlamps where pulsing pretty good) to have them test the battery and new alternator.

I stopped the car, went in, and came back out with the Autozone guy...started the Expedition back up and the car was running perfectly. He went ahead and tested batt and alt and all looked good. Ugh. Turned off car and went in the store for a minute. Came back out, and started the car...and the pulsing was back. I thought, what could have changed between then and now...well, I slammed the hood shut, so it's got to be a connection somewhere. And sure enough, when I jiggled a connection near the firewall (image below) the pulsing stopped. Then i noticed that connection wasn't fully plugged in. I must have hit that connection with my socket wrench trying to remove the #3 spark plug earlier. I don't know what that connection is, but it certainly needs to be plugged in

Oh well, it's solved now. And I've got a brand new alternator to boot! I'm just calling that purchase preventative maintenance...to help me feel better about myself.

 

[rtbrjason]

Thanks for the image! It's a bit tough to see but I'm certainly going to investigate the connections in that area on mine now.

 

[neilzonwheelz]

Here's a better pic. I didn't actually take any pics of my car, so had to search google for a these. Good luck!

 

[FordandPolaris]

Yeah that is the main engine fuse, or at least related to it. Very important haha. Nothing wrong with replacing something before it breaks though in regard to your alternator.

I did the same thing with my CV axles while trying to diagnose a bad humming noise. It turned out to be the year old wheel hub I had put in, but the new CV axles were already installed so I just left them.