I meet all the requirements at the bottom of not replacing the tranny. How do I get my hands on a good valve body? One that would have the updated control valve body. It shouldn't be to hard to replace.


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

Stop by BLUE MOON Steve's shop in grand rapids he has been doing Trannys for over 30 years at his own shop, he will fix you up.

This service bulletin pertains to 4l60'es that have a worn bore in the lock-up oil circuit,what happens is the valve eats the bore out then when your driving the lockup clutch doesn't lock-up completely. When the computer senses a 200 rpm drift between commanded rpm's and actual rpm's it knows the lock-up clutch is not completely holding,once it does this twice for 2 key cycles it throws a code 1870 (a generic slip code). The upgraded valve body has a .470 dia valve vs a stock .440 dia valve and IF the problem hasn't damged the torques convertor lock up clutch lining it's fixable with a upgraded valve body (they gauge how damged the convertor is by how much debris is in pan,how burn''t the oil is and whether the convertor has burn't the paint off and started to turn blue). This problem is also fixable/preventable with a 45$ transgo shift kit which also contains a redesigned valve that rides in the good part of the bore.
As far as YOUR symptoms,the upgraded valve body isn't going to fix it unless something else in the valve body happens to be stuck. The slipping caused by a bad tcc circuit valve lets the transmission slip slightly when lockup is commanded,your problem is much greater the "neutralizing" your describing is 10 times worse. Typically when a vehicle does what your describing and shutting it off and restarting it makes it work again I would still say the convertors one way clutch is freewheeling or pump is damaged allowing it to lose its prime hot,Smitty

also,a code 1870 is a generic code,it means the trans has slipped more then 200 rpm's for a certain length of time during 2 consecutive key cycles,ANY component that allows the trans to slip will cause this code to be thrown,Smitty

Update:

So far I have changed the fluid (it was scorched) and the filter, also I had my brother reset the code message P01870. I have driven the truck for a week now and have not had any problems. The transmission actually is smoother and shifts better than when it was installed after the rebuild.

When my brother had the pan off he said that it had minimal amount of fuzz on the magnet, but the fluid was trashed in his opinion. He hooked it back up to his Diagnostic reader and it hasn't tripped the code again. This is the first time that I have not had a check engine light in years.

Thanks,
Jason