4L80E - Harsh 2-3shift - Experts needed

O

olds403

Member
Joined
Jul 2, 2004
Guys...got a problem with my hauler 2003 Chevy 2500HD w/4L80E.
After the temp goes over about 150F, I get this nasty 2-3 shift and a check engine light. GM tech tells me about TSB No. 08-07-30-001.

Truck is not under warranty and has 72k miles. I pulled the pan and its clean. Fluid is clean and no debris. I regulary changed the fluid in this truck and really don't understand why this has happened.

I've pulled apart Turbo350's and 2004R's before, but not something this complicated.

Any ideas where to look ? Have time...
Any manuals or tips are much appreciated. Just can't afford to replace this tranny at this time. I've roasted my share of tranny's, but I've babied this truck from day one.
 
Wait till code(check engine light) reappears, once the code is stored in PCM you might be able to drive to local Autozone/Advance/Napa auto parts store and have them read the code(s), write them down, then diagnosis can begin.
The good news is lack of debris in pan, which would indicate clutch/hardware problem, might be as simple as one of the speed sensors or TCC controls(solinoid or valve wear issue) Good luck.

Kevin.
 
If the codes were set as a hard code, the scan tool should be able to retrieve it from history. You shouldn't have to wait til the DTC is lit, again.
 
It's OBD II, no such thing as hard or soft code, if it sets the service engine soon light, it's stored in memory until it's cleared which most techs do after reading codes. Normally the tech would write down the exact codes for customer before referring them to a service bulletin, if it was checked at dealership he may have wrote them down on service order hardcopy which the cashier might not have transferred to customer copy, P1870 is excess slip code usually relating to TCC, but there are other codes relating to incorrect ratios that external sensors could be suspect.

Kevin.
 
"It's OBD II, no such thing as hard or soft code"..
Whatever..
I think folks get the jist of the post.
 
Had a shop run a scan. Only code is P0101.
Which is for mass airflow...so I am told. No other stored codes.
They want to pull the tranny apart and charge me a fortune. No way.....
Any help appreciated.
 
If Mass Air thinks your under hard acceleration(low vacumn) that could very well explain harsh shifts, if there was actual trans slip you would have had trans related code. Hope that does it. good luck.

Kevin.
 
Actually there are pending codes in OBDII. Pending, set, and history.

So I would say yes there are soft and hard codes.

It depends on the scanner you are using whether you can see pending codes or not.
 
I stand corrected, I have always considered OBD II to be non-forgetting, in previous ecm's they would "forget" if problem did not reappear after a number of start cycles, my appoligies for my previous statement.

Kevin.
 
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