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4l60e no 4th gear

 
Old 02-09-2019, 07:33 AM
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Default 4l60e no 4th gear

I have a 2010 silvarado 4.8 4l60e i had to change the tcm . All gears shift nice it commands 4th gear but it seems its still stuck on 3rd . The rpn goes high as the speed goes high too . Theres to much load on the engine after the 4th gear if i want to speed up . What may cause this no dtc codes detected .
please find a log file attched
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Old 02-09-2019, 06:08 PM
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If it is being commanded I would suggest removing and inspecting the 4th servo also make sure the small bleed hole at pan under servo has not become blocked .
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Old 02-10-2019, 03:49 AM
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Here is alog file
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File Type: hpl
SILVARADO 1.hpl (3.81 MB, 7 views)

Last edited by Mohammed Aldabos; 02-10-2019 at 04:10 AM.
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Old 02-10-2019, 05:35 PM
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I swapped another servo on and i still have the same problem .
Does it look like a mechanical problem or electric as i dont have any codes on its confusing . I have a 4l80e laying around and i may just swap that
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Old 02-10-2019, 05:39 PM
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I do not have the ability to open the file . But if its being commanded its certainly mechanical. But since the band is both 4th and 2nd it would have to be either the servo, band clearance or stuck 3-4 shift valve IMO.
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Old 02-10-2019, 05:55 PM
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Yea it commands all 4 gears right . I swapped a servo so its not the servo . Checked all wires .
i had the same problem before i rebuild the transmision so i dont want to tear it down again and end up the same thing .
sometimes when it changes all gear up to 4 then stop drive again the vcm shows current gear still 4 when the speed is like 10 .
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Old 02-10-2019, 06:17 PM
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Why is it stuck in open loop?
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Old 02-10-2019, 06:19 PM
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I dont have o2s on at all .
does that make a shifting problem
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Old 02-10-2019, 06:25 PM
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Stock tune file i am using .
does a diffrent os t42 tcm cause this issue i took this tcm out of a 2008 subrban
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MY FILE.hpt (962.2 KB, 4 views)
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Old 02-10-2019, 06:28 PM
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Originally Posted by Mohammed Aldabos View Post
I dont have o2s on at all .
does that make a shifting problem
Why not?
Theres something going on. I see it shifting from second to fourth at low speed/low rpm.

Is this an actual silverado or a 4.8 and 4L60E out of a silverado swapped into something else?
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Old 02-10-2019, 06:31 PM
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Originally Posted by Mohammed Aldabos View Post
Stock tune file i am using .
does a diffrent os t42 tcm cause this issue i took this tcm out of a 2008 subrban
Are they both for a 4L60E?
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Old 02-10-2019, 06:39 PM
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Its an actual silvarado 1500 .
Both for 4l60e . I have the 17 pin plug for the 4l60e . .
Yes it shifts all gear on low speed and rpm . ???
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Old 02-10-2019, 07:40 PM
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Originally Posted by Mohammed Aldabos View Post
Its an actual silvarado 1500 .
Both for 4l60e . I have the 17 pin plug for the 4l60e . .
Yes it shifts all gear on low speed and rpm . ???
The only other easy thing I can think of is make sure the rear gear and tire size matches the silverado.

I'm not very familiar with the GM TCM stuff. I've done the older GM PCM's, and Dodge ECU/TCM's.
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Old 02-11-2019, 03:02 AM
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Rear gear and tyre size is stock the car only done 49000miles
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Old 02-11-2019, 03:50 PM
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Any help please i want to know if my problem is electrical on tcm pcm . Or mechanical . So 8 can decide to rebuild the tranny any or swap it .
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Old 02-11-2019, 08:12 PM
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I think you would be better to post this in the tuning section with your log file , https://ls1tech.com/forums/pcm-diagnostics-tuning-7/
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Old 02-15-2019, 07:29 PM
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Performabuilt (Frank?) is being too humble when he wrote "... But since the band is both 4th and 2nd it would have to be either the servo, band clearance or stuck 3-4 shift valve IMO."
I can state unequivocally that every 4th gear problem (in the transmission) ever reported here was due to one of those issues. Usually it is the servo, a few times the OP fixed the problem with a new(ish) valve body.

I briefly looked at your log file and your tune. 4th gear is getting commanded at 39 MPH; TPS is at 35% at that moment. I do notice that according to the tune, 4th gear should not be commanded until 55 mph at 35% TPS but I might be missing a detail.

I would suggest NOT "Swapping in a 4L80E" as that is a big effort and might not even solve the problem. Be sure you are installing the 4th gear piston the correct way and that its seal is good. Worst case, you might try a different valve body.
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Old 02-16-2019, 05:43 AM
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Thank you guys for ur help
i changed the servo and i still have the same problem .
I have a slip 3rd gear now i am goung to rebuild the trany again i will look carfuly for the 3rd and 4th piston .
i have a code p0717 iss sensor and the speed drops untill i clear the code can i just just disable that or its a must fix so the tranny reads a speed of it . I need to get to know my exact problem to slove with the next rebuild .
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Old 02-16-2019, 04:05 PM
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The TCM definitely needs to read the ISS sensor; no one has ever found a "tuning trick" to disable it.
Reading everything again, is this the original 4L60E (or almost identical 4L70E) or did the transmission get rebuilt or replaced? If replaced, it has to be a unit with ISS.
Was the TCM replaced with the same model TCM? What is the TCM part number?
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Old 02-17-2019, 05:09 AM
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I talked to the previous owner he said he replaced the tranny the same as the older one 4l60e . And i just rebuild the tranny 3 weeks ago or so . It has an interbal p/n switch with 17 pin conector on . I checked all wiring wire by wire all conected . Yes it has an iss sensor hust behind the oil pumb . The older tcm os 242521140235/24252955
new tcm os 242345037081/24238856
ecu e38 os 12633238
Here is a pic of the plug i have
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