transmission problems????

[race_b51]

I have a 1998 ck1500 305vortec engine 2wd auto. trans. (dont really know the number for the transmission), with overdrive, it has about 135000 miles on it. Dont know if trans. fluid or filter was ever changed as I have only had the vehicle for the last 18000 miles. It seems like after it warms up the shifting starts "bucking" hard that can be felt throughout the whole vehicle, from first, to second, etc. sometimes it is harder bucking than others........does this mean its slipping???? Also my "service engine soon" light came on at around the same time this problem started.....................seems like when truck is cold and I drive it for a short distance it does not do this as bad...........any insight or advice will be much appreciated..........thanking you guys in advance.....

Race

[MyTOY]

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 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.

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.

[Arrowshooter]

Next to valve wear is the seperator plate in the valve body lets the check balls bore in when hot and stick causing the the computer to raise the pressure and thus the hard shifting. No matter what you need to have it looked at.

[race_b51]

Thanks for the information...........what do you think about Cottman transmission service, they are basically telling me they have to pull it out and check the valves and while they have it out they will check everything else out and only replace what is needed..........???? sounds like a rebuild overhaul job is coming??? I am new to this area and its the closest tranny place supposingly with a good reputation.........they want about 400 dollars just to take it out, and apart to check it all................I am getting the same song from the STEALER DEALERSHIP here also..........but more money......to pull it.....................Do they need to pull it for the TCC valve replacement etc. and should I let them check it all out???? The truck has 136000miles on it and other than this problem its in great shape..........thanks again for your insight

[troy1]

get it scanned. look for a possible P1870. then report back

[Arrowshooter]

The only need to pull tranny would be if there is metal or a mound of clutch material in the pan. All repairs mentioned above can be fixed with just pulling the pan. I'd check with another shop.

[race_b51]

Scan is definitely coming up with the P1870 code, (460l GM junk transmission) that from what I understand is pretty common, Cottman still tells me due to the milage (136000) they need to pull it, take it apart to change the valves and check pumps etc. tourqe converter and all..........I hear good things about them and bad things, not this particular shop franchise but cottman nationwide in general, just trying not to get screwed too bad...........and it is pretty close to home..........I am going to tell them if I give them the job, I want all the used parts that were replaced..........