code 1870

[kensr199]

Could anyone tell me how to correct a code 1870, "transmission module unstable"?
Thanks
Ken

[GMCTech]

P1870 is transmission component slipping. (You may have pulled the definition off a generic scan tool?)

P1870 usually entails removing the valve body and cleaning really well. The most common cause is a hanging valve. There is a tranny shop trick, but I wouldn't suggest it to the shadetree mechanic.

But, before you worry yourself about all that, when was the last time that you serviced the transmission? Try that first. Clear the code, and let us know if the code returns. (It very well might.)

THere are many components in the transmission that can slip, or cause slip, and it may be time to have the transmission overhauled. But try servicing first, we'll talk horror stories later

By the way, what year and how many miles on your Jimmy?

Hope this helps.

[kensr199]

Originally Posted by GMCTech

P1870 is transmission component slipping. (You may have pulled the definition off a generic scan tool?)

P1870 usually entails removing the valve body and cleaning really well. The most common cause is a hanging valve. There is a tranny shop trick, but I wouldn't suggest it to the shadetree mechanic.

But, before you worry yourself about all that, when was the last time that you serviced the transmission? Try that first. Clear the code, and let us know if the code returns. (It very well might.)

THere are many components in the transmission that can slip, or cause slip, and it may be time to have the transmission overhauled. But try servicing first, we'll talk horror stories later

By the way, what year and how many miles on your Jimmy?

Hope this helps.

Thank-You GMCtech.
It's a '96 jimmy w/86k on it. & yes, the code reader was a $40 cheapo.
Thanks again.
Ken

[Robert Ducros]

Originally Posted by kensr199

Thank-You GMCtech.
It's a '96 jimmy w/86k on it. & yes, the code reader was a $40 cheapo.
Thanks again.
Ken

I just paid 400.00 for the valve body cleaning,it did not do the job. It still shift hard from 1st to 2nd, but no slippage.It shifts normal when I reset the code error and on local runs. When I get on the highway and go 70mph for about 5 miles the error code comes back, and shift hard form 1st to 2nd. If I stop the car and turn off the ignition, restart and go, its ok till I run it on the highway. HE removed valvebody, installed modified TCC/PWM valve assembly. Gaskets, solenoid screens.NEW SHIFT SOLENOIDS, AND NEW SEPERATOR PLATE. DID I GET SCREWED, I GUESS IM RUNNING ON BORROWED TIM. NO MORE TOWING THE BOAT WITH THIS ONE.

[Robert Ducros]

Originally Posted by kensr199

Thank-You GMCtech.
It's a '96 jimmy w/86k on it. & yes, the code reader was a $40 cheapo.
Thanks again.
Ken

I just paid 400.00 for the valve body cleaning,it did not do the job. It still shift hard from 1st to 2nd, but no slippage.It shifts normal when I reset the code error and on local runs. When I get on the highway and go 70mph for about 5 miles the error code comes back, and shift hard form 1st to 2nd. If I stop the car and turn off the ignition, restart and go, its ok till I run it on the highway. HE removed valvebody, installed modified TCC/PWM valve assembly. Gaskets, solenoid screens.NEW SHIFT SOLENOIDS, AND NEW SEPERATOR PLATE. DID I GET SCREWED, I GUESS IM RUNNING ON BORROWED TIM. NO MORE TOWING THE BOAT WITH THIS ONE. :

[USAFweaponstroop]

Robert ( or anybody)...I was reading your tread about your P1870 Transmission Components Slipping. And in your post your discribed WORD FOR WORD the exact problem I am having with my 97 Chevy Tahoe 4x4. If you don't mind me asking, what did you do to take care of the problem? and how much did you end up paying? If you can email me back I would very much appreciate it, my email address is [email protected] Thanks, Joe

Instead of not be able to tow a boat, I can't tow my quads

[blazee]

Usually, if servicing the tranny doesn't help...... the valve body will need to be replaced. Check out this thread for more info:
http://www.automotiveforums.com/vbul...d.php?t=461182

[USAFweaponstroop]

Thank you for the reply and the great thread on tranny problems. I recently had my tranny serviced, I also when with Mobil 1 syn. fluid, and the problem doesn't occur as often as often, only when I take a long drive, or pull a load. So should I replace my Valve body beforce i look into rebuilding my tranny? and is it likely to fix my P1870 problem? Well, I also have about 168k on my Tahoe. Thank you for your help, Joe

[blazee]

With the problem only occuring after long drives, that's a pretty good sign that it is the common problem of a poor tcc apply body caused by wear to the valve body bore. It most cases replacing the valve body is all that's required, however, if this has been going on for a while, there's a good chance that you've damaged your transmission.
You should be fine without rebuilding it if:
The tranny fluid doesn't look or smell burnt.
The torque convertor doesn't look discolored as though it has been overheating.

If you drop the pan and find metal, then your tranny won't last much longer without a rebuild.

[USAFweaponstroop]

Yes after a drive the Trans Fluid does smell burnt, and with the mileage I have on the tranny a rebuild seems the best way to go. But a rebuild fix the problem with my valve body? I very much appreciate the help. Thanks, again, Joe

This may sound like a dumb question but how much life does the motor have with about 170k on it, before it should be rebuilt?

[blazee]

IF you have it rebuilt, you'll still want to change out the valve body with the new updated one or you'll more than likely end up with the same problem again.

As for the engine, if properly maintained these engines will last a long time. A lot of them go past 300,000.