I found this post by Dreamsteve in Blazerforums, he found this using AllData, which is the same program my neighbor used to find it, just thought I would share the info.





General Motors Informative
GM service bulletin about code p1870 - GM service bulliten about code P1870
Posted By: NJBOB on 2/28/2006Location: Collingswood, NJ

This GM service bulliten might apply to your vehicle:
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

 

Same information I linked to above...

The TPS sensor is located on the driver side of the throttle body.

 

OK i will connect my multi up to it next day off I have. Ill post back my results

 

Voltage seems smooth through the spectrum,and the numbers for it on the scanner show smooth transition also. After the 2qts I swapped out it seems slightly better,dont see why though fluid smells like new and looks like new

 

If you like go ahead and let someone sell and replace your transmission but here is my suggestion! Check around and see if you can find a minor vacuum leak! This can simply be the big round hose that goes from the fuel injection to the power brake hub! This is normally a push in connector which has about a 1/2 inch hose clamped on it! If there is any kink or the connector is not in correctly a leak will occur and the transmission will shift rough as though you will be thrown out of the vehicle! Try unplugging this connector and plug it back in hard and straight and maybe you will be lucky and fix your problem. If the vacuum is correct your transmission will shift better than you have ever experienced!