Downshifting but not in tow haul and alternator not charging issue

425EXPEDITION · June 11, 2012

Truck is a 2009 GMC 2500 H/D C/C 4X4 6.0 6 speed

I tried to look for posts but couldnt find any I thought were on here. Anyway when I slow down to a stop my truck downshifts by itself without tow/haul mode on. If I remember right there was a post about it being a brake switch causing this ?

I also have the low rpm not charging problem, Like others especially plowing the alternator doesnt charge until it feels like it,lol

Are there bulletins on these problems ? If so what info is available about it so I can get it fixed without hearing its normal.The truck is coming up to 36 mos warranty expiring and want to get these thing taken care of.

Thank you in advance.

425EXPEDITION · June 14, 2012

wow,this is really sad

00Silverado4x4 · June 14, 2012

Take it to dealers until it gets fixed. If no go contact GM directly to forward your problems up. I personally have no others suggestions other than get it scanned for codes. Sorry.

GMC Tech · June 14, 2012

Straight from the owners manual.

For vehicles with a voltmeter gauge, this gauge indicates the battery voltage when the ignition is turned on.

When the ignition is on, this gauge indicates the battery voltage.

When the engine is running, this gauge shows the condition of the charging system. The gauge can transition from a higher to lower or a lower to higher reading. This is normal. If the vehicle is operating outside the normal operating range, the charging system light comes on. See Charging System Light for more information. The voltmeter gauge may also read lower when in fuel economy mode. This is normal.

Readings outside the normal operating range can also occur when a large number of electrical accessories are operating in the vehicle and the engine is left idling for an extended period. This condition is normal since the charging system is not able to provide full power at engine idle. As engine speeds are increased, this condition should correct itself as higher engine speeds allow the charging system to create maximum power.

The vehicle can only be driven for a short time with the readings outside the normal operating range. If the vehicle must be driven, turn off all accessories, such as the radio and air conditioner.

Readings outside the normal operating range indicate a possible problem in the electrical system. Have the vehicle serviced as soon as possible.

What you describing may be a normal condition.

425EXPEDITION · June 15, 2012

Never mind

gmtech4 · June 15, 2012

why are you pissed ? if its under warranty ,just take it in ,dont look to find something to TELL them what is wrong ,,,techs/advisors/managers phuckin hate that ,the tech WILL check for bulletins ,he WILL scan it and hopefully find SOMETHING and fix it so the store gets a a good survey response from you !!

do you understand me bud,? all good man

425EXPEDITION · June 25, 2012

woah dude,im not pissed. im more surprised i wasnt able to find anyone with knowledge of these issues. i have read about these issues and thought it was on here,guess i was wrong, but they have been discussed online and have been addressed. if service techs,advisors etc. have a problem with a customer telling them about the issue and not liking it well thats just too bad.i know my service writer and hes told me if i have a problem and have info he would like to know.it still amazes me how misinformed even some dealers can be.. most times if you dont bring it to there attention all you get is the usual no problem found. i certainly dont need someone to read there manual info to me. there have been problems with the charging issue and there has been a few people that have had it resolved by a reprogram to the computer, if i go to a dealer without that info i will get just what the other guy read from his manual,nothing. the majority of truck owners will never have an issue with it but for me and others who use the truck to plow it could be a problem.yeah i have the 145 amp alt.and plow package but that has nothing to do with it. theres a change in what the computer tells the alt. to do and it is fixable. if the truck is scanned it wont show a problem for the charge issue.and dont even think of telling me that my truck downshifting when it is NOT in tow haul mode isnt a problem ? again i was looking for info from someone that has had the problems not someone who thinks because the dealer says its normal that everything is ok.some dealers live by what the scanner says and that isnt always the way to correct things.im not pissed at all just looking for real answers.peace out.

gmtech4 · June 26, 2012

telling the advisor as much info on the complaint is great !!! what i meant was telling them what to do is not good ,,,

can't give real answers unless real truck is in front of us......

good luck ,,sorry we couldnt help further for you

Doug_Scott · June 26, 2012

Back when I was on the bench, having a customer tell me what was wrong, and how to fix it, almost always ended up with them pissed that I did not do what they said. Did not matter that I fixed the issue. This was before the internet was invented. I can imagine it is much worse now. Funny how the customers with the answers could not manage to repair it themselves.

All a customer needs to do it give correct complete symptoms. Adding what you think it may be will likely lead the technician down the wrong path. For some reason this reminds me of one customer, he was in his late 60's, had the car all packed up for his yearly trek to Florida. Came into the shop madder than hell that there was a rattle on the right side of the car. Complained that we just serviced the car the day before, and now he is going to late leaving for Florida. He walked beside me the whole way to the car, bitching all the way. As I got to the car, he said he would drive to show me. He still had his keys, I walked up to the passenger side door, pulled his wifes keys out of the lock, and handed them to him. Wished him a nice trip. Did not wait to hear his response, but his wife did.

00Silverado4x4 · June 27, 2012

Going back a few years I was at the dealer getting my truck serviced and decided to wonder the lot while waiting. As I walked out of the waiting area I watched a very similar situation. At least both parties were in better moods over the cause of the "problem"...lol

425EXPEDITION · June 27, 2012

Im not nor would I ever go in and tell them what to do. I know what im doing ive had many,many new vehicles(mostly trucks) as well ive been in the automotive industry for longer than I like to remember. I think I know how to handle myself at 46 but again I was looking for info about the problem.

I just found what I was looking for the charging thing.anyone interested follow the link.enjoy

http://www.plowsite.com/showthread.php?t=106962&highlight=charging