??? for BIG AL --- expertise needed

[MudNurI]

I hope you can help-

I am having major problems with our D/A.... the symptoms of the transmission- gets stuck in 3rd gear wont shift to 4th- stays at 40 MPH, 3,000 RPM's..until you let off the gas- and "slowly" get back past 4th.... today it tripped the SES light- I was searching the boards, and found this thing--

General Motors P0700 Transmission Control System

but there is no description- the only thing is that the guy with this truck seemed to have the same symptoms as what's going on with mine. The truck goes in on Monday for the new bearing kit, seatbelt replacement, and hydro-booster leak... what should I ask these guys to do to figure out whats up with my tranny- now that its tripped the SES is there a "memory" in the computer so they can read what it was that caused it?---

does this seem as simple as a "re-flash" being needed? or is this serious crap?

I appreciate any and all help you can give me, I love my truck and the thought of not being able to get away from the power strokes, and cummings it not sitting well with me.

thanks!
Brandy

you may email me directly if need be- gmcsuburban@yahoo.com

[DmaxMaverick]

Hi, Brandy.

I hate to jump in on Big Al, but....

Two things come to mind on the tranny. Have you changed your spin on filter lately? If not, do so before taking it to the dealer. If the filter is the problem, you may get a surprising bill. The other, I almost hate to mention, is the tranny fluid level. Of course you've checked that. The Allison seems to be sensitive to the level. Good luck!

[mackin]

Brandy,


I think Big AL is at the rendezvous ....... You'll probably have it in the shop before he gets a chance to respond .......

Have you seen this post ? This is the SES code you are getting ....... Also seems you are not alone with this issue ........ Hopefully yours will be repaired as well ,simple, and quickly ........

http://forum.62-65-dieselpage.com/ubb/ultimatebb.php?ubb=get_topic&f=7&t=003304


MAC

[ 05-12-2002: Message edited by: mackin ]</p>

[MudNurI]

I'm glad to see that someone else has this problem... sad to say, but at least its not me. My brother in law had tranny problems in his 8.1/A this past winter and they replaced his module....

I checked that link- sounds 100% like mine, get stuck in 3rd... I drove it today- about 125 miles, and it did NOT do this once... now I'm not sure if I just drove differently - or just didn't happen... I tried not to let it happen.....I'm trying to run my tank out- so I can put in some new fuel before tomorrow...1/4 tank left..should be all set for a fill up in the AM...

I will definetly post whats up with this tomorrow afternoon. I will ask the tech and service manager to give me the details- instead of just "your truck needed a reflash"...etc... I'll let everyone know what's up with it..


BTW.. NO service to the tranny- with 25K on it now....
thanks guys!
Brandy

[DetroitBob]

MudNurI. I agree with DmaxMav. Try the spin-on filter. It filters the oil going directly to the valve body /solenoids. Any metal could cause the solenoids to stick. Keep us informed. Good luck

BoB

[DmaxMaverick]

Another thing about the spin on filter is it doesn't bypass. If it clogs, it stops the fluid, or slows it down enough to cause problems. To my knowledge, the system does not have any form of bypass for the filter. A good design, IMO.

[77TransAm]

The early spin-on filter (p/n 29531007) did not have a bypass valve. The two most recent filters (p/n 29537268 and 29539579) do have internal bypass valves. The bypass filters were already in use before the pickup truck version of the transmission went into production, so all pickups should be equipped with the bypass filter.

[sonofagun]

77,

Why 2 part numbers? What is the difference, if any?

Bob

[77TransAm]

The original filter (29531007) was lacking a bypass valve, which is a very desirable feature for cold-start conditions.

The next design (29537268) incorporated the bypass valve and flats near the bottom of the filter to allow the use of a filter wrench.

The current design (29539579) is the same as the 7268 with the exception of the rubber o-ring seal at the top of the filter. The material has been changed to prevent possible blow-outs during extremely cold starts (-40F and below).

[DmaxMaverick]

Thanks, 77!

I don't like the idea of a bypass on the tranny filter. I'd rather have a limping machine now due to a clogged filter, than a limping machine later due to a worn out tranny! I keep a spare filter in the truck, so it can be changed just about anywhere. I've changed my filter twice now (5K and 35K). At the last change, there was a very noticeable amount of metal dust on the magnet. Better in the filter than in the VB. I guess I'll be sure to order the earlier number. Last I checked, they are still available. I still have one left from my first order, which is the older one. Again, thanks.

[DetroitBob]

More trans info. In the Allison 1000 series Operators Manual under Fluid Recommendations, pg 47/48, if the outside air temp is -17* (-27*C) the transmission oil must be preheated before operation or malfunction may occur. Running the engine for 20 minutes minimum is listed as a means of heating the oil.

BoB

[AKDmax]

I would think a heater pad would produce the same results. They get pretty warm. You Alaskans know what I'm talking about. Kennedy sells them.