Engine high idles to about 850 RPM. Charging circuit ?

me2

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My engine seems to high idle at about 800-850 RPM about 80% of the time.

This summer the batteries went dead for no reason that I know of. I put new batteries in last fall. I boosted it to get it running and then put on the battery charger. The battery condition eye was red prior but after I charged it it was green and still is. The batteries have been fine ever since.

Other than the high idle, the engine seems to run normal.

Any idea what is causing the high idle ?
 

Lipka101

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Has it started since it got cold? They have an auto high idle to keep temps up in the winter. ******d? If so what device are you using and are the sensors in the ****** pipe hooked up?

Sent from my SAMSUNG-SM-G890A using Tapatalk
 

me2

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It started doing it this summer in June.

The truck is stock. I changed the diesel particulate filter because it was plugged about 2 years ago. It worked fine until this summer.

It is not doing the warm up high idle. It does that fine when it is cold out. This is a constant high idle at about 850 RPM. Stock is 750 ?

I'm wondering if it is high idling to try to better charge the batteries ? The batteries went dead and it started high idling about the same time.

I've also got an issue with one of the power door locks not working and the interior light isn't coming on anymore.
 

Powerstroke Man 6.4

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Is it cold where your at?

Other than that what voltage look like?

Check for dtc's sometimes when the alternator is on the verge of dying it will kick the idle up and throw a charging dtc (forget the code at the moment).
 

me2

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It turns out it was the charging circuit.

A few weeks ago my alternator light came on. Long story short, I replaced the alternator and the truck no longer high idles. It starts way better too.

It is quite a job to replace the alternator. Don't do it from the top. Pull the passenger wheel and the wheel well. Then it is fairly straight forward.

BTW, there were no other signs that the alternator was going except a low battery and a longer start. The truck totally died about 5 minutes after the alternator light came on. It would have been nice if the CEL came on to flag that it was having charging issues. Luckily I wasn't caught out on the road.
 

My09Ride

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Sort of on the subject.... Had some work done on the truck... 09 6.4. They mechanic allowed me to hang out. He disconnected the crossover wire from the right battery. Had to take the left out> On the drive home at first I saw 11.50 to 11.75 volts... I figured it would come up so quit watching.. I did notice a higher idol.. Check volts again... around 11.25 to 11.50 volts??? Go home and checked he forgot to reconnect the right battery... Would this cause a higher idol....??? any ideas... Hooked back up everything back to normal... 14.0 v charge lower idol??????
 

jray64

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When my truck did this it ended up being the alternator. You might check into it.
 

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