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98 blazer lt 4.3 tranny problems

Old February 15th, 2011, 8:56 PM
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Default 98 blazer lt 4.3 tranny problems

so when i first got the truck i drove it on the highway for about 45 mins and when i got to a stop light then when it was green i give it gas and my rpm went to 3000 and then my tranny did a big loud switch from 1 to 2 gear and i got a code that my A up**** was bad. i did a research on the code and people said they just did a tranny flash and it fixed it well i did that clear the code and the code never came back but my tranny still does not shift good from 1 to 2ed gear but at lest you dont hear that big bang but you still can feel it. i saw some tsb on this

File In Section: 07 - Transmission/Transaxle
Bulletin No.: 01-07-30-023B
Date: March, 2002
TECHNICAL
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 TruckModels
1996-2000 Oldsmobile Bravada
with 4L60-E AutomaticTransmission (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).


and
Bulletin No.: 07-07-30-024
Date: September 27, 2007
INFORMATION
Subject:
Information on 4L60-E M30 Rear Wheel Drive Automatic Transmission Valve Body Reconditioning, DTC P0741, P0756, P0894, Harsh 1-2 Shift


Models
The following new service information outlined in this bulletin will aid technicians in providing easy to follow valve body reconditioning instructions and new illustrations to simplify reassembly of the valve body. This service bulletin will also provide additional service
information documents that are related to the 4L60-E transmission.

Related Service Documents
DTC P0741 - Torque Converter Clutch (TCC) System - Stuck Off. Refer to Service Bulletin 04-07-30-041.
DTC P0756 - 2-3 Shift Solenoid Valve Performance - No First or Second Gear. Refer to Service Bulletin 01-07-30-036F.
DTC P0894 - Transmission Component Slipping. Refer to Service Bulletin 06-07-30-007.
Harsh 1-2 Shift. Refer to Bulletin PIP3170E.
If valve body cleaning is not required, Do Not disassemble the bores unless it is necessary to verify movement of valves.
Inspection Procedure
Using the exploded views in this bulletin, inspect each bore for freedom of valve(s) movement and evidence of debris. Pay particular attention to those valves related to the customer's concern.
Verify movement of the valves in their normal installed position. Valves may become restricted during removal or installation. This is normal due to small tolerances between the valves and bores.
If a valve is restricted and cannot be corrected by cleaning the valve and bore, then replace the valve body. Describe the restricted valve on the repair order.



Valve Body Spring and Bore Plug Chart (inch)




Left Side Control Valve Body Assembly



Right Side Control Valve Body Assembly
Be sure all solenoids are installed with the electrical connectors facing the non-machined (cast) side of the valve body; otherwise the solenoids will bind against the transmission case as the valve body bolts are tightened and damage may occur.
Disassembly/Reassembly
If a valve is restricted by a metal burr from machining that bore, remove the valve and burr, then inspect movement in the valve's normal position. If no other debris or restrictions are found, then reassemble the valve body and install in the transmission.
If the valve body has been contaminated with debris from another transmission component failure, then disassemble all bores for complete cleaning of all valve body components. If possible, keep individual bore parts separated for ease of reassembly. Use the illustrations in this bulletin for a positive identification and location of individual parts:
Using GM Brake Clean, or equivalent, in a safe and clean environment (clean aluminum pan), clean the valve body and dry it with compressed air. Use appropriate eye protection.
Clean individual valve body components with GM Brake Clean, or equivalent. Coat each valve with clean ATF and reassemble in each bore. Check each valve for free movement during assembly of each bore.
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