Diagnostic Help Please.
Thread Starter
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Tuned
Joined: Jan 2004
Posts: 476
Likes: 13
From: Hickory, North Carolina
Diagnostic Help Please.
PROBLEM:
Truck shifting with a thud from 2nd to 3rd.
POINTS OF INFO:
Original transmission replaced in 2019 at 310K miles with a Jasper.
All other shifts are smooth and normal.
The higher the RPM the harder it shifts.
WHAT HAS BE DONE/CHECKED SO FAR:
I greased drive shaft splines. (long shot I know it was easy to do)
I found no issue with the U joints.
* My regular Mechanic is on vacation but one of his guys checked the following concerning the transmission.
No error codes found.
All shift points were in spec.
Fluid level correct. (I had already checked this BTW)
He also did a "Reset".
What do you guys think? Is the shift solenoid a possibility?
Thanks in advance!
David
Truck shifting with a thud from 2nd to 3rd.
POINTS OF INFO:
Original transmission replaced in 2019 at 310K miles with a Jasper.
All other shifts are smooth and normal.
The higher the RPM the harder it shifts.
WHAT HAS BE DONE/CHECKED SO FAR:
I greased drive shaft splines. (long shot I know it was easy to do)
I found no issue with the U joints.
* My regular Mechanic is on vacation but one of his guys checked the following concerning the transmission.
No error codes found.
All shift points were in spec.
Fluid level correct. (I had already checked this BTW)
He also did a "Reset".
What do you guys think? Is the shift solenoid a possibility?
Thanks in advance!
David
Lead Driver
Joined: Oct 2005
Posts: 6,129
Likes: 1,919
From: Ponca City, OK
Are you sure it's the 2 to 3 shift and not torque converter lockup? I'm not a transmission guy and the little I do think I know I learned here. That said I think the firmness of the shifts is mostly a product of the fluid pressure, and I would guess the solenoid is more of a "it works or it doesn't" kind of thing.
Thread Starter
|
Tuned
Joined: Jan 2004
Posts: 476
Likes: 13
From: Hickory, North Carolina
Are you sure it's the 2 to 3 shift and not torque converter lockup? I'm not a transmission guy and the little I do think I know I learned here. That said I think the firmness of the shifts is mostly a product of the fluid pressure, and I would guess the solenoid is more of a "it works or it doesn't" kind of thing.
David
Lead Driver
Joined: Oct 2005
Posts: 6,129
Likes: 1,919
From: Ponca City, OK
Can you give a little more detail on this thud? Like is it every time the shift happens, up and down, is it an audible noise or a felt jolt. Is the flexplate original or was it replaced w/ the transmission? Are there any mods done to the truck and is it chipped?
Thread Starter
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Tuned
Joined: Jan 2004
Posts: 476
Likes: 13
From: Hickory, North Carolina
It is felt and heard. The faster you accelerate the more noticeable it is.
Flexplate was replaced with the transmission.
No mods to speak of and no chip.
David
Lead Driver
Joined: Jul 2017
Posts: 6,860
Likes: 2,335
From: WV
I would say best place to start is with some live monitoring (FORScan) to know exactly what “shift” you’re dealing with. Udsuth is correct as this could be TC LU and not actually a gear change. I think we need to know before moving on. FORScan is also the recommended tool for pulling ALL codes.
Throttle position comes into play with shifting. Have you seen any issues with needing more throttle than usual?
Throttle position comes into play with shifting. Have you seen any issues with needing more throttle than usual?
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Thread Starter
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Tuned
Joined: Jan 2004
Posts: 476
Likes: 13
From: Hickory, North Carolina
I would say best place to start is with some live monitoring (FORScan) to know exactly what “shift” you’re dealing with. Udsuth is correct as this could be TC LU and not actually a gear change. I think we need to know before moving on. FORScan is also the recommended tool for pulling ALL codes.
Throttle position comes into play with shifting. Have you seen any issues with needing more throttle than usual?
Throttle position comes into play with shifting. Have you seen any issues with needing more throttle than usual?
I will have to educate myself on FORScan, I'm not familiar with it though I have seen it mentioned on the forum many times. Sorry to be ignorant on that.
David
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Lead Driver
Joined: Jul 2017
Posts: 6,860
Likes: 2,335
From: WV
I’ve never actually used FORScan myself even though I’ve purchased and have the app on my phone. My Edge monitor has been able to do everything I need so far thankfully. But I’m ready just in case.
The tech folder at the top of our forum has an entire section on FORScan. Some of the guys around here are good with it and can help out too.
Basically at this point I think you’re going to want to see live data of shift command (my Edge display will show). It should give you gear command and lockup command somehow. By watching it you can see what is actually changing during the harsh shift.
The tech folder at the top of our forum has an entire section on FORScan. Some of the guys around here are good with it and can help out too.
Basically at this point I think you’re going to want to see live data of shift command (my Edge display will show). It should give you gear command and lockup command somehow. By watching it you can see what is actually changing during the harsh shift.
Lead Driver
Joined: Oct 2005
Posts: 6,129
Likes: 1,919
From: Ponca City, OK
Yeah you can monitor the gear commanded PID to see what the PCM is asking for and the shift solenoids for on/off which depending on the combination tells you which gear your in. There is also a torque converter lockup PID and slip PID that may be useful in your diagnosis.
FTE Leadership Emeritus
Joined: May 2014
Posts: 27,354
Likes: 5,946
From: Lake Hartwell, GA
These links should be helpful.
Thread Starter
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Tuned
Joined: Jan 2004
Posts: 476
Likes: 13
From: Hickory, North Carolina
Lead Driver
Joined: Jul 2017
Posts: 6,860
Likes: 2,335
From: WV
Unless you want to go the wireless dongle route and pair with your phone. I think the BAFX phone version guys have luck with is cheaper than the one you linked.
BAFX Products Wireless WiFi (OBDII) OBD2 Code Reader & Scan Tool/Wireless Check Engine Light Diagnostic Scan Tool for Cars & Trucks/for iOS. iPhone & Android Devices (1) https://a.co/d/8gzePm9
BAFX Products Wireless WiFi (OBDII) OBD2 Code Reader & Scan Tool/Wireless Check Engine Light Diagnostic Scan Tool for Cars & Trucks/for iOS. iPhone & Android Devices (1) https://a.co/d/8gzePm9