throttle and TC unlocking.

[PenultimateLap]

hello all. been noticing some weird behavior while driving namely the TC unlocking and and revs rising while cruising on highway. i checked the codes and it said throttle position sensor malfunction under ABS secction. I thought that was odd, but i noticed that at idle tand he absolute throttle pos was 9-11%. this makes me think that the ecu is reading a higher throttle input, and therefore jumping out of lockup and trying to accelerate. i get a similar willingness to hold gears while ddriving around town as well. i replaced the TPS. with no change. next is the pedal sensor i guess. anyyhing else i should look at. im assuming the % should read near zero at ide. thanks.

 

[afpj]

Lots of knowledgeable members on this forum that could help ( I'm not one of them) , but it would be immensely helpful if we had more data...year and specific model of vehicle, miles on it, maintenance done ( tranny replaced? Maf replaced, and what brand, etc) , what code reader you using, have access to bidirectional scanner? Help us help you.

 

[swathdiver]

You can unplug it, take it off the car and clean it real good, even the ends of the throttle plate and see if that helps. Due to age, it might just be time for a new one. The code and symptom follow on just might tell you why.

 

[rockola1971]

This sounds more like the 2-4 band is slipping which seems like the torque converter is unlocking (TCC). Check your fluid! Smell burnt? color go from pinkish to a orange or even brownish?

 

[NickTransmissions]

This sounds more like the 2-4 band is slipping which seems like the torque converter is unlocking (TCC). Check your fluid! Smell burnt? color go from pinkish to a orange or even brownish?

Could be; depends on how much rpms rise when whatever is happening happens. Typically you'll see 500-700+ rpm rise when the band slips vs a couple hundred when the tc clutch comes off. If the band is just begininning to wear to the point of slippage, it may not have started to slip yet in second...

hello all. been noticing some weird behavior while driving namely the TC unlocking and and revs rising while cruising on highway. i checked the codes and it said throttle position sensor malfunction under ABS secction. I thought that was odd, but i noticed that at idle tand he absolute throttle pos was 9-11%. this makes me think that the ecu is reading a higher throttle input, and therefore jumping out of lockup and trying to accelerate. i get a similar willingness to hold gears while ddriving around town as well. i replaced the TPS. with no change. next is the pedal sensor i guess. anyyhing else i should look at. im assuming the % should read near zero at ide. thanks.

How big is the RPM increase when this happens?

Wondering if you're actually falling out of fourth gear.

Any other shifting issues at all (ie slipping from first to second)?

 

[PenultimateLap]

well, just lost 3rd and 4th on the freeway yesterday! so you guys were on the right track. it was only 200 ish rpm fluctuation which seemed like TC, but then it quickly escalated to a much bigger range, and then just started freewheeling in 3rd. luckily i was a cruise home in 2nd. so thats where im at! guess i need to call around trans shops today.

 

[S33k3r]

Keep in mind that if the transmission shops want more than your current budget can allow, you can buy a used one from FB Marketplace, Craigslist, etc. Just look for part outs of 4L60Es, and make sure they are 4WD transmissions. I stalked you to find out what vehicle you have (2003 Suburban Z71 for anyone else wanting to give advice).

 

[NickTransmissions]

Keep in mind that if the transmission shops want more than your current budget can allow, you can buy a used one from FB Marketplace, Craigslist, etc. Just look for part outs of 4L60Es, and make sure they are 4WD transmissions. I stalked you to find out what vehicle you have (2003 Suburban Z71 for anyone else wanting to give advice).

Ive rebuilt quite a lot of "good used" transmissions, especially 4L60Es as the 3-4 pack likes to go out shortly after the buyer installs it.

well, just lost 3rd and 4th on the freeway yesterday! so you guys were on the right track. it was only 200 ish rpm fluctuation which seemed like TC, but then it quickly escalated to a much bigger range, and then just started freewheeling in 3rd. luckily i was a cruise home in 2nd. so thats where im at! guess i need to call around trans shops today.

If you're able to r/r the trans yourself you'll save anywhere from $700-1000 in labor.

Also, see my 4L60e thread for parts considerations and make sure the parts i list as "required" are installed. Get pricing based on that list as some shops dont replace things like electrical components or one way clutches unless you ask for it.

 

[rockola1971]

Looks like I got this keyboard diagnosis right. Sorry to hear OP.

 

[PenultimateLap]

thanks guys. normally id tear into it myself, but i dont have the space or time at this point. just evaluating if its worth the repair at this point.