Check charging system message.

[Tungsten06]

Hey guys. Need a little help again.

A couple weeks ago my check engine light came on. Checked the code and it was P0340. I did some research and found out its a common problem with the alternator. I took the alt off yesterday and dropped it off at a local shop for a rebuild. They confirmed the bad diode problem and got rid of the stock clutch pulley on the alt. Installed the alternator this afternoon and all seemed well on the test drive. Did a little bit of running around but eventually got the check charging system message and the battery light came on after dark when I turned on the headlights/fogs, but Im not having any noticeable issues. Made another stop and started the car back up but didn't get the message again until a couple mins of driving.

Any suggestions on where to start looking for the cause? Is it possible that the battery was weak from being disconnected for a day and I need to drive it to charge the battery or is there possibly still an issue with the alt?

 

[Joser281]

I say is still the Alt. because I had driven to work (45 miles) a few times in my stang with a weak battery, had to jump it every day with a portable charger to start by the way, and had never gotten a "check charging system" message.

 

[Tungsten06]

I think it probably is too, but I really am trying to avoid having to shell out a few hundred for a new one.

I dont know if this info will help, but this morning I noticed that the volt guage would sit in the middle of the guage at idle and go up to about 3/4 when driving.

 

[Chrome61]

Check the 3-wire plug that goes to the alt. Mine was loose, I would push it in and after a couple days got the Check charging system again, I replaced the plug and never had the problem again.

 

[eyeeatrice]

I had the same issue when I was putting in a new battery in my car in the dark! BAD IDEA, the posts on the new batter were opposite of the last one and I got sparks and smoke. Bought a new alternator from ebay off at an amazing price. The problem ended up being the wire that plugs into the back of the alt. Replace that wire and if it doesnt fix it, pm me and ill send u my old alt if u pay shipping. Im almost positive the old alt is fine.

 

[08gt4u]

i think alternator too.i had to take my alt back to the guy that rebuilt mine 3 times before he got it working.

 

[bradleyem]

If you can, put a volt meter on the battery while the engine is running. If your volt gauge is going up that much, then the alternator may have a bad regulator and be overcharging. My alternator recently failed in this way, and the volt meter was reading 19 volts at idle, which is too high. Hot temperatures will kill alternators quickly.

I also had my alternator go bad before while driving from Missouri to Ohio in the hot August heat. The firestone that I went to put in the wrong alternator which was not made for the PCM to control voltage regulation. The alternator was charging, but I still got a Check Charging System message and battery light about 20 minutes after I got back on the road after leaving the shop, which was of course closing when I left. I drove it home that way with no problems, but took it to a local firestone to have the correct alternator put in under warranty. I'll be changing my alternator for the 3rd time this weekend

 

[Tungsten06]

I appreciate all the responses guys. I took the alternator off the beginning of last week and checked the plugs and everything else. Put everything back together and still got the message. I finally just took the alt back to the shop that rebuilt it, and it looks like they only replaced the diodes cause the regulator was bad. Been back on for a few days now and it seems to be working like a charm.

 

[discofan]

Check the wiring from the alternator to the battery...

I did some work on my motor and when I took the alternator out, I must have broken a connection on one of the small wires inside the large wiring cable that goes from the alternator to the battery...

Had to strip off the electrical tape off and fixed the broken conection....

No more "Check Charging System" alert!!!

Try it...

Dave