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Discussion Starter · #1 ·
I have a problem with my transmission on my RM wagon-96.
The 4th gear wont go in until i let off gas.
And driving on the highway when i press the gas just a little it will downshift from 4th to 3rd.
And wont shift back to 4th until i let off gas.
No slipping on 1-2-3 and shifts nice.
TCC is working perfect.
Any ideas??
Can it be leaking servo seals on 4th apply servo?
Or has it something to do with 4th accumulator?
The seller told me the trans is rebuild.
Sorry for my bad english i,m from sweden.

[ 07-07-2007, 10:54 AM: Message edited by: mbc ]
 
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Discussion Starter · #2 ·
before condemning the tranny i would look at the data stream and see what the pcm is comanding to make sure it is not an electrical ptoblem or sensor problem tps can cause this to happen but again you need to see the data stream
 
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Discussion Starter · #3 ·
Ok, i will look at data stream,
i have an obd2 cable can you suggest any software that can help me,
Thanks
 
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Discussion Starter · #4 ·
well iam pretty much privy to a tech 2 becuase i ama GM tech but any tuning software should be able to read that not to up on the tuning side of the house i just a tranny tech and drivabiity
 
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Discussion Starter · #6 ·
i,ve checked with proscan and it all looked normal.
1-2-3 perfect then it feels like it tries to get into 4th but wont shift until i let off the gas.
Then it jumps out of 4th if i give it just a little gas.
I even tried another tps but the fault is still there no change.
I read in another topic that leaking 4th circuit.
I will check the 3-4 accumulator piston tomorrow probably is that a good start or any other ideas??
Is it the same piston in th700?? i have a bunch of those laying around.
 
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Discussion Starter · #7 ·
Let me know how that leaking circuit thing checks out. That is probably my post you have read about a very similar sounding problem. The only difference I see is that mine works fine sometimes and like you describe others. I noticed yesterday when it was acting up that the 2-3 shift was delayed at light throttle conditions about 10mph. Are you seeing the same thing?
 
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Discussion Starter · #9 ·
I didnt got thr time to look at the car maybe next week...
My boss is driving me crazy
 
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Discussion Starter · #10 ·
Is it speed related? I posted a while ago about how my tranny won't go to O/D until >50, irrespective of programming or throttle position. I'm wondering if I have a bad electrical connx or something else going on. Everything looks find in Datamaster. BTW, I believe Datamaster is OBD-1, only.
 
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Discussion Starter · #11 ·
No it is not speed related,even if i go 70-80 mph the 4th wont go in until i let off gas.
 
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Discussion Starter · #13 ·
I removed the 2 accumulator pistons and replaced the o-rings.
No difference.
My shop will take a look at the car in august.
 
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Discussion Starter · #16 ·
Not yet, i,m working my ass off so i dont have time for the car.
It is going to the mechanics on wednesday.
I promise i,ll keep it posted when i get this fixed.
 
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Discussion Starter · #17 ·
Originally posted by mbc:
.....
Sorry for my bad english i,m from sweden.
Are you kidding me? :eek:
It would be great if some of the American misfits on this forum could communicate IN THEIR NATIVE LANGUAGE half as well as you do!
To your issue: Sorry I didn't see this post earlier, but it sure sounds to me like a programming issue rather than a hardware problem.
I can't help you because I don't have any software for OBD2, but it would be good if you could read your program and send it to someone with OBD2 capability.
To any of you RM wagon owners who may be reading this: Does the factory programming prevent 4th gear engagement at WOT like many of the cars through the 80's and 90's?
 

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Bump… ever any resolution to this, I have the same problem????
Well, it was 15 years ago since last post, so probably no. Best to datalog it and confirm the PCM isn't the problem, then you know the transmission probably has an issue in the 4th gear apply hydraulic circuit.
 

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I have a problem with my transmission on my RM wagon-96.
The 4th gear wont go in until i let off gas.
And driving on the highway when i press the gas just a little it will downshift from 4th to 3rd.
And wont shift back to 4th until i let off gas. No slipping on 1-2-3 and shifts nice.
TCC is working perfect. Any ideas??
...
[ 07-07-2007, 10:54 AM: Message edited by: mbc ]
... 1-2-3 perfect then it feels like it tries to get into 4th but wont shift until i let off the gas.
Then it jumps out of 4th if i give it just a little gas.
… ever any resolution to this, I have the same problem?
Not a problem - a feature, intended by GM.
Under 110MpH, while the throttle is over 43.7%, 4th gear is avoided.
Until the throttle relaxes under 43.7%, 4th gear is not permitted under 110MpH.
If you're in 4th, you're under 110MpH, or you're under 43.7% throttle - or both.

Only LT1 B-cars with 3.08 (GU4), are programmed to exceed 108MpH.
 
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