Transmission function

[m-35tom]

I noticed today that when I put the trans in neutral and come to a stop that at near zero mph the trans locks the driveshafts, holding the truck with no brakes applied. 2006 A1R. Normal? And how reliable?

 

[dmetalmiki]

What vehicle is that?..And no, it should not lock up in neutral at all.
There is a brake band doing the wrong thing in there..probably trying to lock two? or more epicyclic trains together?
Out of adjustment on the selector..?
Does the gearbox have a 'Park' Position?
If it does then something is definitely 'skew wiff'.
UNLESS, Of course that vehicle has a "Function" I never heard of..But then, you never know.

Just a thought..(Not an obvious one..but), Did you check the brakes?.

Addendum.

And you do not say if the vehicle IS automatic, Or manual.

IF, It is a manual gearbox, Then the selectors are out of positioning.

OR, The gearbox and engine ;Overcome; A resistance fault somewhere else on the vehicle.

I am though curious...Please do report back on the 'fault' and it's remedy.

 

[m-35tom]

well I guess I will just ignore this reply then!

 

[Third From Texas]

Normal.

My 2008 A1R does the same.

When I got my first truck the previous owner told me to 1) always be at a stop, 2) never shift directly between D and R (proper operation is D>N>R , R>N>D). I've always been in a habit of that, but still noticed that my new truck does in fact hold on it's own in N.

 

[doghead]

Are the TMs available for these trucks?

 

[Floridianson]

Yea do not think I will try the roll thing but as Texas said I always do a complete stop in drive or reverse then neutral.

 

[Third From Texas]

Are the TMs available for these trucks?

Yes. Well, sort of.

I have a revision for the A1 thru 2003.

Unfortunately, I think it deals mostly with the 3126 implementations and not the later C7 but I have yet to do more than scan a few .pdf files. It must be installed due to the search software and how it hotlinks images and diagrams. I've been too busy with the truck. LOL

 

[fuzzytoaster]

Are the TMs available for these trucks?

Unclassified but limited to Government and contractors only according to the APD. The TM9-2320-391-23&P is what we need but it's an ETM so yeah.

I noticed today that when I put the trans in neutral and come to a stop that at near zero mph the trans locks the driveshafts, holding the truck with no brakes applied. 2006 A1R. Normal? And how reliable?

I have 5 A1/A1R trucks with the C7 ranging from 2003 to 2008 and none act that way. When slowing down to stop does it cause a sudden jerk or whip lash? Also reliable what exactly?

Yes. Well, sort of.

I have a revision for the A1 thru 2003.

Unfortunately, I think it deals mostly with the 3126 implementations and not the later C7 but I have yet to do more than scan a few .pdf files. It must be installed due to the search software and how it hotlinks images and diagrams. I've been too busy with the truck. LOL

Correct. It covers truck up to 2003 focusing on the 3126. There are some references and pictures to the C7 setup but limited to operator troubleshooting the PDP modules. It's basically useless for the C7 trucks. I've reached out to a few contacts in service in attempt to get schematics or something on our trucks but it's been difficult.

 

[m-35tom]

Come to a stop on a hill, put in neutral, release brake. The truck will not roll. Consensus seems to be it is normal. Maybe it is an attempt at a 'park' function. So is it reliable as in will it hold the truck stationary as long as engine is running.

 

[fuzzytoaster]

Come to a stop on a hill, put in neutral, release brake. The truck will not roll. Consensus seems to be it is normal. Maybe it is an attempt at a 'park' function. So is it reliable as in will it hold the truck stationary as long as engine is running.

Your original post made it sound like it would lock up on flat ground. Only my 2008 A1R will hold on a hill in neutral but only on an incline. If facing the decline it will roll forward. I've not tried to put it in R and back up a hill to test that hold direction. From what I've read it was a safety measure for both operator and equipment. I'm assuming the obvious rolling backwards into something on a hill but possibly drive line whiplash or internal wear if rolling backwards then applying heavy throttle.

 

[Suprman]

Maybe its an allison feature. Several civilian trucks have a similar feature.

 

[NDT]

How are you supposed to use the winch then? Pto locked out in D and wheels locked in N?

 

[Suprman]

The a1 winch system tells the trans electronics to stay in neutral and kick up the engine rpms.

 

[fuzzytoaster]

How are you supposed to use the winch then? Pto locked out in D and wheels locked in N?

That was my initial thought but I've not had an A1 with a winch to test specifics yet.