2000 astro strong shift when hot

[fomongo]

when cold start ands run like new,has 125,000 miles, but after runnig it for along period of time 45 minutes or so,when stops that goes to second gear shifts really strong and bang goes less as it changes to the last.Last time gave me check engine light,Code was P1870(traansmission component slipping,is this something that may go away with changing fluids and kit or may be more serious?

[Blue Bowtie]

Changing the trans oil and filter is almost always a good idea. Getting some clean oil into the valves, servoes, and accumulators certainly can't hurt.

[fomongo]

I `m going to give it a chance there`s nothing to loose and new oil and filter wo`nt hurt. thanks for reply

[Supergumby]

On a high milage 4L60E the TCC regulator valve will get worn in the valve body, and the (T)orque (C)onverter (C)lutch will not fully apply. On a long highway drive, the computer will see excessive slippage in the transmission, set this code, and then shorten (firm up) the shifts and raise the line pressure to 'save the transmission'.

That's the 'banging' shifts you feel.

Depending on how long it's been doing this (slipping), you may be able to simply replace the valve body and be fixed. otherwise, you may also need to replace the converter...if the internal lockup clutch friction material is too badly burned.

From the Service bulletin:

TSB # 01-07-30-023A
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, 1999 (Julian Date 9015)
This bulletin is being revised to update the Parts Information. Please discard Corporate Bulletin Number 01-07-30-023 (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. These valves are used in all transmissions produced after January 15, 1999 (Julian Date 9015), 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




GOOD LUCK........

[fomongo]

thank you for some great valuable info,is much appreciated,thanks again