View Full Version : HELP!! ALLISON FAILURE - Need ideas before 7am
MountainMax
10-31-2002, 22:01
While driving tonight I lost the light which shows which gear you in on drive, neutral and reverse. The service engine soon like came on and the transmission won't shift above third. While parked, when I shift through the gears, I makes a LOUD CLUNKING noise going from park into reverse, reverse into a forward gear and when you go back to park. I got under the truck and had my wife shift through the gears. The noise is coming from inside the transmission. It sounds like my old Z71 would when the transfer case for the front wheels locked in. Any Ideas on what it might be would be appreciated. I'm taking in in the morning.
chevmeister
10-31-2002, 22:15
http://forum.62-65-dieselpage.com/ubb/ultimatebb.php?ubb=get_topic&f=7&t=004164
check ths post??? may help.
Cross fingers that it's just the NSBU switch and the clunking is just the normal noise when shifting...
mountainmax,
most likely, it is the nsbu switch. when it fails, trans. goes into limp in mode(3rd gear only), you loose the prndl indicator light, disables tcc engagement, and raises fluid pressure. the clunk noise is most likely because of the increase in fluid line pressure. the dealer should be able to diagnose easily, trans should set a code(p0708).
hope this helps,
77TransAm
11-01-2002, 09:22
Sometimes a failed NSBU will send the trans into hydraulic default, which only gives you third and reverse. Since no trim is applied during shifts when in hydraulic default, the trans will really slam into gear as full line pressure is applied without modulation. If it's just a bad NSBU, the trans should return to normal operation once it is replaced and the codes are cleared.
MountainMax
11-01-2002, 13:02
Well thanks to you guys I went to the dealer loaded for Bear this morning. I followed the other threads on the subject, I am convinced that the NSBU switch is probably the cause. We Had 11 straight days of rain in Houston with light steet flooding so I've been driving alot in the rain. I show up this a.m. at the dealer and tell the service writer what the truck is doing, and, I believe I know whats wrong and even the parts #s. He stares at me for a moment and goes "I'm going to go talk to the shop foreman" 15 #@%&* minutes later he comes out and says that the shop foreman said that for that switch to fail, I had to have driven my truck through high water because the switch is sealed and besides that's not what's causing the problem. I explain to him what I've learned here. That the 01 models had an unshielded switch and that the foreman is right, the switch is sealed....on the 02s and 03s but not on the 01s and thats my point. It was UPGRADED BECAUSE IT TENDED TO FAIL!!!!. He stares at me again , I see the lights go on and he dissapears again. After 15 more minutes I walk into the service managers office and explain I just want some one to write up a work order and fix my truck no matter what the cause is. Now he gets involved. The shop foreman finally shows up and has sheets of paper he's pulled from his computer with service bulletins about losing the shift indicator and he tells me its part of the ignition and has 3 wiring schematics. I look at them and there all for the 460LE and 480LE trans. and the Escalade etc. I say this is an Allison, and I don't see that mentioned. He says it's the same wiring scheme. I then show him the thread here that shows several people with the same symptoms as my truck and all had the NSBU switch replaced. I asked him to explain that. He couldn't. He said that the information on these sites is unreliable and dated. He then asked me if I had serviced my trans and put an outside filter on. Well if you look here, I posted a warning about Allison service. I told him that they had just flushed it a month ago but that THEY didn't include changing the outside filter in their service. I did it myself. I met with same service mgr. on that occasion and complained about them not knowing to do it. Well at this point the shop foreman goes " oh yeah we just had a meeting about that." I say "oh yeah? thats cause I raised hell last time I was here. You had a meeting because of me, and now you're asking me if the filter has been changed. I find that amusing."
Anyway the trucks in the shop. My money is on you guys. I'll keep you posted on when he figures out he's a moron and you are right. Thanks for the help.
[ 11-01-2002: Message edited by: MountainMax ]</p>
77TransAm,
So with these things failing here and there, what can a guy do to "cobble" it up and make it work? I'm sure there must be a way to do this???
MountainMax
11-01-2002, 13:37
John: The good thing about it is I had 35548 miles on the odometer when I went in. I will drive it home fixed. If they say it failed because I drove it through high water and its not covered they're in for a fight. Thank the Big One, this is my first problem with the truck and the warranty had about 2 more days on it. FWIW, I appreciate all you contribute to these forums.
deerhunter7
11-01-2002, 13:39
It's amazing that this board knows more than the Dealers. GM should force the Dealers to read the Diesel Page !!!! :D :D
JK,
Maybe the old "hammer rap" will get ya home ;)
You KNOW I would try it! Actually, I figured maybe a jumper wire or something...
77TransAm
11-01-2002, 14:22
kennedy, I've never tried to make one work that had died... once the new NSBUs became available we replaced all of our old black ones with new tan ones. Haven't had a failure yet with a new one.
As far as the black ones failing, water is bad, but slush and salt seem to be the elements that cause the most failures.
Freightliner (?) making any ground on there recall.....???We should join in.....I guess I'll have to get a spare and stick it in the glove box......
MAC
MountainMax
11-04-2002, 12:03
Chaulk another one up for the Board.
Picked up my truck Friday afternoon. The service writer had a sheepish look and the shop foreman was nowhere to be found. Of course it was the NSBU switch. The mech. even noted on the paperwork there was no water in the failed switch. I think the service writer felt bad about all the hassel I was given in the morning because when I went to the cashier, they gave me a big piece of cheesecake.
Thanks again guys.
Are you sure it was cheese cake??? :eek: :eek:
MM
Dito on what "Smorey"......Perhaps the have away of getting back !!!!!! :D
How you feeling???? ;)
Got a case of "WET TAIL" since you picked up your truck???? tongue.gif
MAC smile.gif
BowTieDmax
12-01-2002, 09:46
Well first snow of the season. And while checking oil wells today I pulled in a drive, did what I had to do. I went to leave and the truck backed up about 30ft then it went into nuetral. I tried to shift it back into gear but it was lighting up only 3rd gear once, then moved forward about 5ft and thats it. Now the shift indicator wont do nothing.
It's Sunday, first snow of the season (I plow), ands its opening day deer seaon tomorrow morning and my truck is sitting in a oil field drive way 10 miles from home.
Well I removed the NSBS. I guess I use the wifes yukon for hunting tommorrow as my wife borrows someones car to find me a new switch at a dealer.
I quess I should of took someone advice off of here to get a spare in the glove box.
Paul
ChevysRus
12-01-2002, 11:54
Damn Interesting, is the NSBU internal or external? Dumb question I know cause if it's getting wet and slushy it has to be external right! So how come when the stealer replaced my NSBU he had to pull the pan and add 3 qts of ATF? Just makes you wonder doesn't it. Not only that, but I think he replaced it with like for like or black one for a black one so I have another failure to look forward to in my '01.
OH well, by the time the '05's are out maybe 50% of the dealers will be up to speed ont hese trucks.
Have a great day all! Only 22 more days until we turn the corner towards spring ha ha ha
ChevysRus
External? Right.....
Man I'd luv to see that service slip......What a screw up....You didn't have to pay anything did ya???Me I'd have to find out their reasoning,their S/M ,foreman and Techs name,who signed off on that one.....They were able to drop pan re-bolt up and only lose 3 quarts?????
MAC :confused:
What is the switch part number and is it hard to replace. I've a 2001 and I'm worried about a failure. I'm out of warrenty but this sound like a factory messup.
Powered by vBulletin® Version 4.2.5 Copyright © 2024 vBulletin Solutions Inc. All rights reserved.