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I have a 96 Impala SS that the tranny just went out in. I went and got a re-man tranny but it isnt shifting right. I hooked up a snap-on diag. scanner to see if it had any info to my problem and the only thing that I can see is that the tranny line pressure is low. After flushing out the tranny cooler and hooking up an intercepter (its supposed to raise line pressure) the problem still remains. I'm no expert on tranny's by any means but the only other thing that I can think of that is left is the computer, I read somewhere that it controls tranny line pressure. If anyone has any insight to this Thank you in advance.
 

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4l60e

try disconnecting tps, this should not only set code for tps but will cause max line pressure.another way to increase line pressure drop pan unplug the pressure solenoid also sets a code. does the trans shift or should I ask slip when all shifts occur? does scanner show shift adapt or codes for low tps volts?
I have seen bad computer in 96 truck that I use as shop truck, it set codes of low tps volts I replaced tps, wires to tps and some other engine component's .at the end only thing that worked was that I replace computer and all problems solved.

does transmission company agree with your guess or have you asked them yet?
 

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Discussion Starter #3
It shifts from 1st to 2nd fine but when it shifts to 3rd is when it slips a little, almost like you are driving a standard shifting gears. The tps voltage is within tolerance from the scanners readings and it shows no codes from the tranny. I told the tranny people what was going on and they just swapped out tranny's for me so this is my second re-man doing the same thing. I'll try your suggestions tomorrow and see if that helps before I go get another computer. Thanks for all of your help.
 

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4L60E Line Pressure problem {possibly]

Poor line rise problems are some what common with 1996 GM vehicles.

The computer has ground issues. GM has an updated wire harness to address this concern.This harness is cheap and easy to install.

I will post the part # in the morning when I get back to the shop.
 

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You the man...thanks so much for the info. I've been driving my 67 impala SS around for the past week and it's not the most everyday driver friendly. Again, thanks so much.
 

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some folks simply run a ground wire from the trans to the battery neg post.

If the trans is shifting up and down like it should ( cept for that slippage in 3) I would think there is a good enough ground for the pressure control solenoid to function.


HAs there been an actual pressure gauge installed on the trans? Checking for pressure readings?
 

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4L60E Line pressure problem[possibly]

The AC Delco part # is 12167310. This is to correct,in their words,poor internal ground,which causes pressure control solenoid voltage to remain high during heavy throttle acceleration.

If the ground issue is causing your problem this will fix it,but.

Crosley brings up a good point,did you check this with a gauge?

Again this is an easy repair,but if you should need to install this kit and there are no directions with kit please post back and I will post them.Good luck!

Tony, I've run ground wires to computers before to fix ground issues[Isuzu] with success,but this kit has you swapping wires around at computer,probably best to stick with kit,if ground is issue.Dana.
 

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Discussion Starter #8
I havent checked it with a guage yet, I've been depending on the snap-on scanner for that. When I go pick up that part I'll get a guage to take before and after readings. You guys have been a big help!!! Thanks a bunch.
 

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4l60e

opinions are different on this one, guessing at what could be wrong on the net can be tricky, ground trouble would show up in many ways. no pressure raise unplug your harness from tranny see what happens in reverse.

when harness is on ground for pressure solenoid will or should duty cycle (rapid on off) to regulate line pressure. (shift feel)
when you unplug the harness you should get a much firmer shift in reverse, and this will set all the transmission codes. you can not check drive as all shift solenoids are off you get third gear only in drive.

as cosley pointed out if third is the issue, pressure may not be the trouble
we have agreed to disagree on what your trouble maybe but we all want to help.
 

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4L60E line pressure problem [possibly]

Airworld, you are a true gentleman.

We may not agree,but it is true, we all want to help. :)

I can't wait to see those pressure readings!
 

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the deal here is ;

all of the questions or suggestions can point to / find or fix the problem.

Out here in the dry climate we do not see the corrosion issues the rust belt tranny shops do.
 

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Discussion Starter #12
Sorry it took me sooo long to post an update, but here is the deal. I went and got a new computer and that jumper wire that Briscoe recommeded and installed them. My old computer was bad, atleast thats what the dealer told me when I brought my car up there to get the new computer flashed. Soon as I got all that going line pressure went up and everything started shifting right. HELL YEA!!
 

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4L60E Line Pressure problem[possibly]

Good news Olimpalarider,glad it worked out,just wish you had tried the ground update first,to qualify the true failure.

But your rolling again and thats great!
 

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After talking with the guys I got the re-man from to make the warrenty valid I had to get a new computer that jumper wire installed. I wish they would have told me the that long time ago when I was troubleshooting and pulling my hair out. But as you said, I'm rolling again and thats all that matter. Again thanks a bunch, you guys were a big help.
 
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