# transmission shifting hard (auto trans)



## MicrophoneFiend

So this morning I get in my truck and drive to work and my transmission is shifting very hard from first to second and into third gears. Does anyone have any idea what my be going on? It just started this morning. Just drove it to San Diego and back to Bakersfield with no problems and put about 550 miles round trip this weekend (no towing). My truck is a 2000 Chevy 3500 dually. Help a brother out cant be without my tow rig. Truck has about 118k on it. No slipping no loss of power just shifting really hard.


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## CoupeDTS

is it shifting at different times than normal too?


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## tearitup

is the check engine light on?
you need to pull codes.

Some DTCs can put you in a "limp home mode." it will set the line pressure to max and make it shift hard to avoid slip. it may even start in 2nd gear.

always pull codes first. i have seen shops replace trannys when the actual problem had absolutely nothing to do with the transmission.


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## lilmikew86

heres a couple easy fixes check ur trans fluid level{when warmed up}and if thats good change out ur trans filter and have the tranny flushed might have gooten clogged up wit all the new miles up put on it if thats dosent fix it go to a shop to get a diagnostic


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## kadillak_driver

this happened to me once in my tahoe, never happened again though 

i was city driving for about 20 min and then got on the highway for about 90 miles straight no stopping at all. As soon as i got of on the ramp i noticed the really hard down shifts and then hard up shifts. headed back home and no problems at all except for the up and down shifts. 

Got home and Put the scanner on it and no codes nothing out of the normal. all i did was clear adaptive memory and it fixed it perfect shifts and never again had the problem


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## droppen98

pull you positive cable on you batt try reseting the computer and see it if happens again


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## pink63impala

is it a c,k or w 3500 and what engine? alldata is showing bulitens for valve body repairs

This bulletin is designed to provide easy to follow valve body reconditioning instructions and new illustrations to simplify reassembly of the valve body and list other service information documents that are related to the 4L80X transmission family.

Related Service Document

PIP3427A - SES light on DTC P0757 harsh shifts delayed 2-3 shift no third gear or slip in third or reverse or a 2-3 shift flare. Debris stuck in the # 11 check ball or a sticking pintle in the 2-3 shift solenoid.

Subject:
Harsh 1-2 Upshift, SES, MIL, or CEL Illuminated, DTC P1870 Set 
(Replace Valve Body)

Models:
1996 Buick Roadmaster
1996 Cadillac Fleetwood
1999-2000 Cadillac Escalade
1996-2000 Chevrolet Camaro, Corvette
1996-2000 Pontiac Firebird
1996-2000 Chevrolet and GMC Light Duty Truck Models
1996-2000 Oldsmobile Bravada
with 4L60-E Automatic Transmission (RPO M30)
Built Prior to January 15, 2000 (Julian Date 0015)

This bulletin is being revised to update VIN Breakpoint Date information and revise the Parts Information table. Please discard Corporate Bulletin Number 01-07-30-023A (Section 07 - Transmission/Transaxle).

Condition

Some customers may comment on a harsh 1-2 upshift and the Check Engine Light or Service Engine Soon indicator is illuminated.

Diagnosis

Typically, these vehicles will have been driven more than 32,000 km (20,000 mi) before this condition occurs.

The scan tool may show a DTC P1870 set as a history code.

A harsh 1-2 shift or DTC P1870, caused by wear in the control valve body, may be difficult to duplicate when the transmission temperature is below 93°C (200°F).

Cause

The condition may be due to wear in the control valve body. This wear occurs in the bore that contains the TCC isolator and regulator valves, and results in poor, or no, TCC apply.

Important :

^ DTC P1870 is a type B code. The conditions for setting the P1870 DTC must occur on TWO CONSECUTIVE TRIPS (ignition cycles, with a drive cycle) before setting a P1870 history code.

^ When the conditions for setting DTC P1870 are met (first trip), the PCM commands maximum line pressure and harsh 1-2 shifts are the result.

^ This may result in a harsh 1-2 shift with no history code if the conditions for setting the DTC required for the second trip are not met, on two consecutive trips (Ignition cycles, with a drive cycle).

^ When the conditions for setting the DTC are met, on the second consecutive trip, a DTC P1870 is stored as a history code.

^ When the P1870 code is stored, the PCM will turn on the Service Engine Soon (SES), Check Engine Light (CEL), or Malfunction Indicator Lamp (MIL).


Correction

Install a control valve body with the revised TCC regulator and isolator valves. Refer to the Parts Information table below. These valves are used in all transmissions produced after January 15, 2000 (Julian Date 0015), and all of the service parts currently available through GMSPO contain revised TCC regulator and isolator valves.

Important : If all of the following conditions are true, it is not necessary to rebuild the transmission or to replace additional transmission components beyond the control valve body.

^ Transmission operation is normal before the transmission reaches operating temperature, or before DTC P1870 is set (no slips, flares, or missing gears).

^ The torque converter is not blue or overheated.

^ The transmission fluid is not burned or has no burned odor

^ The transmission fluid pan contains no abnormal debris (clutch material, bronze, brass, or metal fragments).


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## NIMSTER64

I have a 2002 yukon xl the denali. it started not wanting to shift from first to second . when it reach its time to shift I let go of the gas and it shifts into 2nd.od and 4th are fine. can anyone help me out on this one? what steps should I take in fixing the problem?


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## NIMSTER64

oh and one more thing. I turned the tow haul on and it felt like it was on neutral, it just reved up and didn't go anywhere. just started doing this.


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