4L60E shifts from 1st to 4th no kickdown with throttle

[70bird]

Hello all,

This is my 1st real post here, and I'm sorry to say it's because I'm having a problem with my truck,
I have searched this forum and did a Google search for these symptoms. Seems I am the only one Lol. I really need some help here. This is my work truck, and have until Monday to get this sorted out.

As the title says, trans is shifting from 1st to 4th. Possibly 1st to 3rd. It's hard to tell which because it happens almost immediately, as soon as the truck starts to move.

Here's what I know for sure:
1993 K1500 4x4 5.7L 4L60E 140,000+ K
Fluid is at normal level and not burned
No noises, grinding, clunking, or slipping
All forward and reverse gears available
No kickdown available at throttle
NO codes
Will not hold 1st gear manually, will shift to 2nd ALMOST immediately at 5-10 mph regardless of throttle position.
Shifts back to 1st automatically when vehicle stops.
Operating temperature has no affect
When revving in Park, speedo needle will climb to around 10mph, Huh?


I can drive it by manually shifting with no issues, but I don't want to hurt it further if the trans can be saved. I'm praying this is a electronics issue.

I'm going to test the TPS and the fuse for the electronics.(same circuit as MAP & o2 right?)

I should add that the truck starts, idles, and drives good other than a pinging issue under load and poor fuel mileage.
I understand that TPS is one of the sensors the trans relies on for shift points, and may also be my pinging and fuel problem.

Anyway thanks in advance for any help!
Mark

 

[70bird]

Well, TPS checks out OK.
Still trying to figure this out

 

[70bird]

Great news!
Turns out it was a pinched wire in the VSS harness.
After testing TPS, MAP, and VSS to be good, I was figuring a bad PCM.

I decided to bite the bullet and take it to the trans shop. Seems I was wrong about it shifting from 1st to 4th.
It was shifting 1-2-3-4, but so quickly it was hard to tell. They put it on the scanner and found a fault in the VSS.
Even though I had tested VSS sensor and it was good. Speedometer was working correctly too.

When checking for codes at home, (counting SES light flashes) No codes appeared.???
So Yeah, a pinched wire above the bell housing near fuel line.

For anyone in the Redding Ca. area,
Big shout out for Redding transmission!!! They didn't even charge me!

Hope this helps someone else out,
Mark

 

[Dwayne]

Where is the Vss?

 

[70bird]

Mine is 4 wheel drive, so on the transfer case drivers side. On 2 wheel it will be on the tail shaft housing.

 

[jdyates]

Glad you got it figured out! Those 60E's are a pain in the ass lol, lots of stuff has to be in working order for it to work correctly.

 

[Dwayne]

I am so frustrated with my Tahoe and going through another 4l60E it sits in my driveway, Had the vehicle for 5 years and counting and in truth these transmissions are not cheap and the shops are rolling in the cash on labor cost to get you back on the road again. you got lucky on this repair.

 

[70bird]

Yeah, like jdyates said, lots to go wrong with the darn things.
I think I,m gonna start looking for a replacement ahead of time so I can keep my down time to a minimum.
Maybe look into swapping to 4L80E. I need to do my homework for that.

For now, she's shifting great! I don't do a lot of heavy towing or anything so.........fingers crossed.

Mark

 

[Dwayne]

Well the funny thing is its about the money, i found a few shops and yes i can do the job myself but i am wore out on the repair, i been looking into PATC transmissions its a little costly but worth it for the tranny itself and just pay the labor for the install, the first estimated cost for my repair was estimated a 3,350.00 for a standard rebuild in a local shop but getting a good warranty is the key, the 4L80E is the best way to go but you will need to change the cross member and change the computer and drive shaft length, the dirty little secret is out as you see so many good trucks up for sale and parked because of this problem with with transmission, especially when you find yourself depending on your truck everyday. But the question remains on what type of set up you want that will last and these transmissions are everywhere even in the corvettes wise choice to prepare.