"Check Charging System" intermittently coming on

[sledzeppelin]

2004 4.6L, 205k miles. At about 6 hours into a 10 hour drive, the Check Charging System message appeared, and stayed on. This was the first time that has ever happened. After another hour or two, the battery gauge dropped, and then the gauges went out, then headlights dimmed and finally went off. Limped to a hotel. Next morning, charged the battery and kept going, and barely made it to the destination.

Got the alt rebuilt at a shop and replaced the battery which tested bad, and the message went away until about 40 miles into our return trip, and then it kept going on and off. Turned around and went back to the shop, who confirmed it was indeed charging. They took the alt off again and it tested okay. They re-replaced some of the parts and the intermittent message continued. Replaced the three wire plug on the harness, and no change. I do have continuity from the 3 wire plug on the alt to the two wire connector near the A/C tubes.

I got one of those alternator gauges that plugs into the cig lighter, and when the message pops up, the voltage there DOES drop temporarily, and then climbs back up. At idle, the engine surges just slightly at the same time the message comes on. While driving, braking seems to make it appear, but not always. Turning on the A/C makes it come on more often.

Is my next step to replace the alt wiring harness? Because of the slight surging, I'm also wondering if something is intermittently creating a big draw, which causes the voltage to drop low enough for the message to appear.


Now, some further background. A couple months ago, the starter wouldn't even click but the lights would go on. After a bunch of tries, all of a sudden it started. From that point on, when it would start, sometimes the starter wouldn't shut off and would just keep spinning until a fuse blew. One time it didn't shut off and I didn't notice and drove that way and the starter burned out. A shop replaced the starter for me (while I was traveling) and ran a wire from the starter to near the battery, and that's how I've been starting it since - by touching that wire to the + terminal. Could that have anything to do with this?

Sorry for the long post, but I tried to include everything I thought might matter. I've already searched this and other forums and I've seen this problem a lot, but none of the fixes mentioned have solved it for me.

 

[Bedrck47]

Welcome to the Forum

 

[docraymund]

Considering all the travelling that you do, you'd be better off with a brand new alternator to avoid inconveniences. And do voltage drop tests on the charging systems' wiring.

 

[stamp11127]

Welcome to the forum.
What you are describing will usually be caused by a failing voltage regulator, poor contact between pins in connectors or by a break inside one of the wires to the alternator (field wire).

Did the shop replace the voltage regulator?

Throwing parts at a problem is the same as gambling - I prefer to diagnose and repair what is necessary. Troubleshooting intermittent electrical issues can be very time consuming so hang in there.

 

[sledzeppelin]

Thank you for the replies! The shop did replace the voltage regulator.

I will try doing voltage drop tests.

What about the engine surging at idle when the message comes on? Is that a normal thing when it detects low voltage from the charging system?

Thanks again!

 

[Bedrck47]

Have you checked the belt and idler pulley

 

[sledzeppelin]

Yes, we did replace the belt and checked the pulleys. I also didn't mention that the alternator was dead when we first had it checked. One brush was totally gone. So when the charging system warning came on the first time, it was legit.

 

[Bedrck47]

Sometimes when someone is looking for help or suggestion they will get responses like the one I asked That is why it is very helpful that a member post ALL of what was done or parts replaced when they post. It avoids having to repeat the same things over and over.

The more information given will normally result in better replies.

 

[stamp11127]

The surging can be from multiple causes. I would concentrate on one issue at a time.
If you have a meter, monitor the battery voltage with the ac on. Charging voltage is 13.5 - 14.5 volts dc and should remain steady or slowly move towards 13.5 v.

 

[sledzeppelin]

We finally got around to jumping over the fusible link from the alternator, and that made the message go away. It seems that the alt couldn't get back to the battery through it (even though it has continuity) and that was causing the alternator's VR to quickly burn out. THANK YOU for all the help!