97 S10 P1870, I think I fixed it - S-10 Forum
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97 S10 P1870, I think I fixed it

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Old 05-12-2008, 03:52 PM   #1
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97 S10 P1870, I think I fixed it

So about a month ago, I installed most of the Trans Go kit. That only fixed part of the problem. It got rid of the that lock/unlock at light throttle , but the P1870 hard 1-2 shift problem came back. So I added a trans cooler and reset the code. It was good for 1.5 days. After some reshearch into the side mounted servo. This Sat. I installed the balace of the kit, and replace the solinoid. It shifts better, no 1-2 gear shift flair. Solid lock up at 40 MPG. I love It. Now we willhave to see if it can make it through the week without setting a code .
FYI to replace the servo on the side of the trany. You do not need to remove the Y pipe. Just remove the O2 sensor. You will need to modify the heat shield in the tunnel to get enough clearance to R&R the parts (hammer time ). Other than that, carefuly follow the instructions in the other post.
I replaced the solinoid because I hait re-work. Might be fixed, I will give you the update.
Also the graby brake problem turned out to be rear brake shoes with some of the lining broken off.

KP
Old 05-13-2008, 02:53 AM   #2
Inu
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Re: 97 S10 P1870, I think I fixed it

i was thinking my hard shift was too much heat from rat race thru town traffic. so a vette servo will fix it? the transgo? fix the converter lockup? link to the kit, i couldnt find it on their site..

thanx inu
Old 05-13-2008, 03:36 PM   #3
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Re: 97 S10 P1870, I think I fixed it

No, if the CEL is on and if it's a 1870 code.
Typical it will be OK when it's cold. It takes a lot of stop and go, or a little freeway to bring it up to failure temp. So every day things start off OK, but the shifts are a little off. If I was driving on the freeway at about 50 then slowed down and speed back up it would do something strange. It seemed to slip or shift gears slightly back and forth. Anyway after it's warm it starts to shift hard from 1st to 2nd even at light trottle. The problem is the lockup coverter. The trany is taking too long to lock or unlock the convertor. When the computor detects this has occured twice in a row, it goe into OS mode. It desides it's slipping so it turns it's pressure up to the max. You get kicked in the A everytime if shifts from 1st to 2nd.
Why this occures is on of GM's trans improvements. On the older version of this trans. (and those with the shift kit installed) you will feel it when the convetor locks and unlocks. Some bonehead at GM desided this is a bad thing. His fix is insted of just locking and unlocking, he came up with a PWM system that would slowly lock and unlock by slipping the clutch in the convertor. To do this the PWM valve in the valve body bounces back and forth rapidly as the clutch locks or releases, as oposed to just moving once from lock to unlock. Guess what this does? It wares out part of the valve body! Are you getting the big picture yet! GM fixes this by replacing the valve body. The new ones don't have this failure mode (so says GM). The Trans Go kit make all of the shifts short and sharp, you will feel it every time the convertor locks or unlocks. It occures just above 40MPH at light throttle.
Hell, I could have told him that would happen! As part of the kit you will modify the servo and add springs. I do not think you will need a Vet servo after the kit is installed. If you do your homework first, you might get the job done in 5 hours. It took me longer, I did not know how to remove the servo.
Good luck. Also if your fluid is burnt, you will need a rebuild. The seals and clutches will be fried.
Old 05-13-2008, 07:07 PM   #4
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Re: 97 S10 P1870, I think I fixed it

close, but GM developed the EC3 pwm to stop customer complaints of too firm a lockup feel. the early version of the 4l60e the 93 and 94 used a 700 pump modified for use in this application. they also went to pwm for longevity of the 3/4 clutches. in theory it worked, but the dissimilar metals of the iso convertor valve in the valve body, which was steel until 2000 then changed to a type 4 anode hardened aluminum configuration, causes rapid wear in the aluminum casting most noticed exactly opposite the oil feed hole.
DUH, thats not supposed to happen. focking engineers, they redesigned the valve body 6 times since its inception, and it still uses the stamped steel crap ass made in china steel shell. the aftermarket along with trans builders that care have made a killing on these things improving factory flaws.

BTW the 1870 is manufacture specific version of a GENERIC trans component slipping, it could be anything.
Old 05-15-2008, 05:56 PM   #5
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Re: 97 S10 P1870, I think I fixed it

Day three and all's well!
The only strange part is now when you shift into drive, the truck imediately jumps. I can live with it, but there is no pause at all.
Old 05-19-2008, 12:58 PM   #6
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Re: 97 S10 P1870, I think I fixed it

It's still fixed! I did check today and found it's about 1/2 quart low.
Life is good!
Old 05-27-2008, 11:12 PM   #7
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Re: 97 S10 P1870, I think I fixed it

It's still fixed
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