Tranny dancing between 3rd and 4th (Auto)

[blindeyed]

Alright guys.. a couple months ago my tranny started acting up. I would be driving like normal, and normally once I hit 45 mph, the tranny normally shifts to 4th gear. Well after that it would then downshift to 3rd, then upshift to 4th and back and fourth just bouncing between the 2. So what I did was change the fluid and filter, and it seemed to run beautifully after that. But now it's doing it again.. and I'm confused. I'm pretty sure I don't have OD since the console never showed the option, just 1 2 3 D R P. I don't exactly know too much about tranny's, but I kind of know my way around them. Anyone have any ideas? 4L60-E btw...

[ikeyballz]

anything wrong with your throttle position sensor? since yours is all electronic if the sensor says you're going WOT, notWOT, WOT, etc.. then it should do the shifting up and down..

thats the only electriocal thinng i can think of.. i dont know 4L60E's much but i read a crapload on the 700R4's cuz of my bad trans..

and btw, your 4th gear IS od.

[blindeyed]

Originally Posted by ikeyballz

anything wrong with your throttle position sensor? since yours is all electronic if the sensor says you're going WOT, notWOT, WOT, etc.. then it should do the shifting up and down..

I'll have to check that out, I know once I let off the throttle a little and just cruise, it doesn't jump back and forth between the two. But one I get to highway speeds it does it consistently since I have to keep the rpms's pretty high to maintain speed.

Originally Posted by ikeyballz

and btw, your 4th gear IS od.

Are you sure.. because I've seen some consoles read 1 2 D (D) R P. With the (D) being the overdrive.

Idk.. like I said, I'm not too great with tranny's. I'll try changing out that sensor though and see if that helps. I just think it's a little odd that it stopped doing it for a while after I changed the fluid and filter, and just started doing it again.

[fubar1420]

change the shift solenoids. just drop the pan , remove the filter, and they pull right out.

[ikeyballz]

that guy up there seems to know more then i do.. hehe. the solenoids would make sense..

[hotrod_chevyz]

Originally Posted by fubar1420

change the shift solenoids.

I agree.

+ have the transmission flushed. Sometimes thats all they need.

[Blue Bowtie]

That's great, so long as the "flush service" includes removal of the pan, cleaning the magnet, and replacement of the filter AFTER the fluid flush, otherwise the only thing getting "flushed" will be your wallet.

Clean fluid and a clean filter may just solve some problems.

[blindeyed]

Yeah I bought a new TPS sensor, thought it fixed the problem. But it didn't. It's still dancing between the 2 gears and now the SES light is starting to flash on and off. I'm gonna go get the codes read tomorrow. Anyone know where I can find a decent write up on how to change solenoids? If that does end up being the problem then would this be a good time for a shift kit maybe while I'm at it?

I would rather start off with flushing it out first before changing any solenoids.. money is kind of tight. That might be all it does need. Cause like I said before, I have changed the filter, and did wipe the magnet clean, refilled it.. and that fixed it. But I'm not sure how to actually get all the fluid out of there for a complete flush.

[Blue Bowtie]

Shift kit? For a 4L60-E? That would be called a "reprogram" in most places. While you can get upgraded and modified solenoids, separator plates, servoes, and spools, the PCM is going to control everything at it's programmed temperatures, pressures, and VSS inputs as best it can.

[blindeyed]

Originally Posted by Blue Bowtie

Shift kit? For a 4L60-E? That would be called a "reprogram" in most places. While you can get upgraded and modified solenoids, separator plates, servoes, and spools, the PCM is going to control everything at it's programmed temperatures, pressures, and VSS inputs as best it can.

Well TransGo, Jet, B&M, etc all call them shift kits...

I tried getting the codes scanned. Nothing popped up. The guy at Advance said normally the transmission won't throw codes, it just trips the SES light to let you know there is a problem. So I got nowhere there. He said he thinks it could be the pump in the tranny.. which I pray that it's not. I really don't have the time, money, nor patience to deal with that.

[hotrod_chevyz]

"reprogram" just means your changing it from its original settings. My shift reprogram kit was made for a THM 350, wich has no electric parts what-so-ever. Made by Transgo.

I bet the SES light is from changing the TPS.

As for the transmission, I would just flush it and see how it acts. I bet it fixes the problem. If it doesnt then yes, a shift kit would be the next step.

[blindeyed]

Well what steps are involved with flushing a transmission. I know how to change the fluid, filter, etc.. but how do I do a thorough flush?

[hotrod_chevyz]

Originally Posted by blindxeyed

Well what steps are involved with flushing a transmission. I know how to change the fluid, filter, etc.. but how do I do a thorough flush?

Just take it to have it done by a reputable company. Dont tell them anything is wrong with it. That way if its still messed up after its flushed, you can blame them for it

[Blue Bowtie]

Not trying to argue, but that TH350 shift kit isn't going to do much good in his 4L60E valve body:



If you're dead set on changing solenoids, change whichever ones you want, but do yourself a big favor and pull the snap rings and plugs to inspect the 3-4 relay valve spool, the 4-3 sequence valve spool (directly behind the 3-4 relay spool) and the spring behind them both. Also look at the 3-4 shift valve spool and spring. On the front of the valve body, there are four plugs for valve spools. The second from the right (passenger side) is the bore for the 3-4 relay and 4-3 sequence, and the third from the right is the 3-4 shift.

[Blue Bowtie]

Originally Posted by blindxeyed

...The guy at Advance said normally the transmission won't throw codes, it just trips the SES light to let you know there is a problem. So I got nowhere there. He said he thinks it could be the pump in the tranny...

No offense intended to anyone, but unless the "guy at Advance" has fallen on really tough times, that's probably why he is a parts counter guy at Advance. If the MIL turns on, there will be either a stored or pending code (the only exception being some years of VATS/PassKey systems). Just because his generic code scanning equipment cannot read the codes doesn't mean there are none. I won't bore you with the pages of possible transmission DTCs for GMs.

Unless the transmission has been severely abused, neglected, overheated, or has over 250,000 miles on it, I would have serious doubts that the problem is with the pump itself. Even one with a heavily worn bushing and scored slew ring will maintain pressure adequate to operate the hydraulics, lubricate the transmission, and hold pressure on servoes and clutch packs if everything else is working properly.

Go with the transmission flush if you want. It can't hurt anything as long as the filter is replaced afterward (again). A dead empty (just rebuilt) 4L60E with a stock converter and 2-7/8" pan will take about 14 quarts for both the converter and transmission.