98 Blazer hard shift

[maryfish]

My 98 Blazer is shifting hard from 1st to 2nd and 2nd to 3rd. Runs fine on the freeway, but when I drive at slower speeds thats when it shifts hard. The Service Engine Soon lite is on. What do you think is the problem?

[ChristianGentry]

I have the same problem, only it's not all the time. I believe it is an electrical or sensor based issue, not an actual transmission problem and here's why...: I am also having other electrical issues and they are as follows:
rear hatch release button will not operate at times, door locks trigger themselves without the key in the ignition, and with the key in the ignition. Blinker relay clicks randomly, although the blinker itself doesn't turn on unless the switch is on. All strange issues that I would be have a common problem in my case, although I haven't been able to fix it yet. If I were you before you overhaul the transmission, have your electrical system checked out in depth as possible,

[BlazerLT]

Originally Posted by ChristianGentry

I have the same problem, only it's not all the time. I believe it is an electrical or sensor based issue, not an actual transmission problem and here's why...: I am also having other electrical issues and they are as follows:
rear hatch release button will not operate at times, door locks trigger themselves without the key in the ignition, and with the key in the ignition. Blinker relay clicks randomly, although the blinker itself doesn't turn on unless the switch is on. All strange issues that I would be have a common problem in my case, although I haven't been able to fix it yet. If I were you before you overhaul the transmission, have your electrical system checked out in depth as possible,

No offense, but how can you give advice on what the problem is if you haven't seen the actual trouble code that was set in this case?

Mary, go to autozone and get the codes scanned for free.

Get the actual code number and not the attendent's redition of it.

Report back with it.

[cobra1]

Harsh 1-2 Upshift, SES, MIL, or CEL Illuminated, DTC P1870 Set (Replace Valve Body) #01-07-30-023B
Harsh 1-2 Upshift, SES, MIL, or CEL Illuminated, DTC P1870 Set (Replace Valve Body)
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).

Parts Information
Model Year
Vehicle Platform
Engine (RPO)
Transmission (RPO)
Transmission Broadcast Code
P/N

1996
S Truck
2.2L

(LN2)
4L60-E

(M30)
SAD
24217855

1996
C Truck

(Mexico)
5.7L

(LO5)
4L60-E

(M30)
CPD
24217856

1996
C/K Truck

G Van
5.0L

(L30)
4L60-E

(M30)
CCD, CFD, KBD, WAD, WBD
24217856

1996
C/K Truck

G Van
5.7L

(L31)
4L60-E

(M30)
CHD, CJD, KCD, CMD, CUD, KPD, YDD, FFD, WCD, WHD
24217857

1996
F Car

Y Car
5.7L

(LT1)
4L60-E

(M30)
FFD, YDD
24217857

1996
D Car
5.7L

(L31)
4L60-E

(M30)
AHD
24217857

1996
S/T Truck

M/L Van
4.3L

(L35)
4L60-E

(M30)
TBD,TAD, MSD, MDD
24217860

1996
C/K Truck

G Van
4.3L

(L35)
4L60-E

(M30)
CAD, CBD, KAD
24217861

1996
S/T Truck
4.3L

(LF6)
4L60-E

(M30)
SHD, TLD
24217862

1996
B Car
4.3L

(L99)
4L60-E

(M30)
BBD, BCD
24217863

1996
B Car

(Includes Police Pkg.)
5.7L

(LT1)
4L60-E

(M30)
BFD, BWD, BKD
24217864

1996
F Car
3.8L

(L36)
4L60-E

(M30)
FCD, FBD
24217865

1997
S Truck
2.2L

(LN2)
4L60-E

(M30)
SAD
24217866

1997
C/K Truck

G Van
4.3L

(L35)
4L60-E

(M30)
CAD, CBD, KAD
24217867

1997
S/T Truck

M/L Van
4.3L

(L35)

4.3L

(LF6)
4L60-E

(M30)
SHD, TLD, TBD, TAD, MSD, MDD
24217868

1997
C Truck

(Mexico)
5.7L

(L31)
4L60-E

(M30)
CPD
24217869

1997
C/K Truck

G Van
5.0L

(L30)
4L60-E

(M30)
CCD, CFD, KBD
24217869

1997
C/K Truck

G Van
5.7L

(L31)
4L60-E

(M30)
CJD, CHD, KCD
24217870

1997
F Car

Y Car
5.7L

(LS1)
4L60-E

(M30)
FFD, YDD
24217870

1997
F Car
3.8L

(L36)
4L60-E

(M30)
CFD, FBD
24217871

1998
C/K Truck

G Van
5.7L

(L31) 5.0L (L30)
4L60-E

(M30)
ADD, AFD, AJD, ALD, AWD, CCD, CFD, KBD, CHD, CJD, KCD
24221155

1998-2000
C/K Truck

G Van

S/T Truck

M/L Van
4.3L

(L35) 4.3L (LF6)
4L60-E

(M30)
TAD, MSD, CAD, CBD, KAD, WBD, SHD
24221154

1998-2000
S Truck
2.2L

(LN2) 2.2L (L43)
4L60-E

(M30)
SAD
24221153

1998-2000
F Car
3.8L

(L36)
4L60-E

(M30)
FBD, FCD
24221159

1998-2000
F Car

Y Car
5.7L

(LS1)
4L60-E

(M30)
FFD, YDD
24221158

1998-2000
C/K Truck

(Includes Police Pkg.) G Van
5.7L

(L31) 5.0L (L30)
4L60-E

(M30)
LHD, LSD, LUD, LPD, KXD, CPD
24221161

1999-2000
C/K Truck
4.8L

(LR4)
4L60-E

(M30)
CCD, CFD, KBD
24221162

1999-2000
C/K Truck
5.3L

(LM7)
4L60-E

(M30)
CJD, CHD, KCD
24221162


Parts are currently available from GMSPO.

Warranty Information
For vehicles repaired under warranty, use:

Labor Operation
Description
Labor Time

K6560
Valve Body - R&R or Replace
Use Published Labor Operation Time

[BlazerLT]

Not good.

The 4L60-E tranny is used in several chev cars and trucks.

[gmedinas]

Hello, I have a 98 blazer 160.000km and also the same problem, here in Caracas (tropical temperature over 35c) the transmission shifting hard 1 to 2 only if drive over highways and slow and run again, for a time, if turn off and on the engine the transmission run ok, also in cooler temperature all work fine.

Think about add any transmission cooler system (radiator) or check other valve ot activator or actuator in bad conditions?, thanks.

[blazee]

Originally Posted by gmedinas

Hello, I have a 98 blazer 160.000km and also the same problem, here in Caracas (tropical temperature over 35c) the transmission shifting hard 1 to 2 only if drive over highways and slow and run again, for a time, if turn off and on the engine the transmission run ok, also in cooler temperature all work fine.

Think about add any transmission cooler system (radiator) or check other valve ot activator or actuator in bad conditions?, thanks.

gmedinas,

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