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Old 11-13-2015, 06:21 PM   #1
solidaxel
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2003 5.3 4L60E Down shifting

When downshifting from 3rd to second and 2nd to 1st there is a noticeable "hard" down shift'
Is this something that is corrected with the computer tuning or is it in the transmission?
Up shifts are smooth and positive for all four shifts, but when slowing down for a light the 3rd to second is a bit too harsh???
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Old 11-13-2015, 06:54 PM   #2
boostedc10
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Re: 2003 5.3 4L60E Down shifting

Stock trans, how many miles, what's the fluid look like, where's the fluid level at, stock converter?

It's much easier to diagnose a trans in person where you can look at pressure and/or log it to see what's going on. Answering the above questions may help myself or other point you in a direction though.
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Old 11-13-2015, 07:00 PM   #3
solidaxel
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Re: 2003 5.3 4L60E Down shifting

Quote:
Originally Posted by boostedc10 View Post
Stock trans, how many miles, what's the fluid look like, where's the fluid level at, stock converter?

It's much easier to diagnose a trans in person where you can look at pressure and/or log it to see what's going on. Answering the above questions may help myself or other point you in a direction though.
Stock trans 75K miles, fluid and filter fresh, top of stick ,converter is factory

Thanks
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53 TuTone Extended Cab 350 4-Spd 3:08 (SOLD)
53 Chevy Moldy pearl green ZZ-4 4L60E 9" 3:25
55 GMC 1st Black Mll (ZZ4) ZZ6 TKO 600 5 sp 3:73
62 Solidaxle Corvette Roman Red (327
340hp 4spd 3:36) C4 & C5 suspension tube chassis
LS 3 4L70E
65 Corvette Coupe 327 350hp 4spd 4:11
78 Black Silverado SWB (350/350) 5.3 & 4L60E 3:42
2000 S-Type 3.0 (wife cruiser)
2003 GMC SCSB 5.3 4L60E 3:42
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Old 11-13-2015, 11:22 PM   #4
clinebarger
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Re: 2003 5.3 4L60E Down shifting

Do you have a different PCM laying around with the VATS deleted? Try that just to prove out that it is Tune/PCM related or not.

Anytime the Throttle is Closed the PCM will command the Lowest Line Pressure via the EPC solenoid. Which is 1.0 Amps of DC Current, Full Line Pressure is Zero Amps. This can be manually read with any Meter that can read Amps on the Positive(High) & Negative(Low) EPC wires.
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Old 11-14-2015, 05:07 PM   #5
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Re: 2003 5.3 4L60E Down shifting

Yes we did switch computers first thing..........no change
O K, I am not sure where the EPC is located?
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53 Chevy Moldy pearl green ZZ-4 4L60E 9" 3:25
55 GMC 1st Black Mll (ZZ4) ZZ6 TKO 600 5 sp 3:73
62 Solidaxle Corvette Roman Red (327
340hp 4spd 3:36) C4 & C5 suspension tube chassis
LS 3 4L70E
65 Corvette Coupe 327 350hp 4spd 4:11
78 Black Silverado SWB (350/350) 5.3 & 4L60E 3:42
2000 S-Type 3.0 (wife cruiser)
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Old 11-14-2015, 06:07 PM   #6
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Re: 2003 5.3 4L60E Down shifting

The EPC is in the transmission but you can read it on pins c (high) and d (low) of the transmission plug.
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Old 11-14-2015, 07:09 PM   #7
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Re: 2003 5.3 4L60E Down shifting

Is this only when you manually downshift, or does it happen on kickdown?
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Old 11-14-2015, 11:13 PM   #8
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Re: 2003 5.3 4L60E Down shifting

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Originally Posted by BR3W CITY View Post
Is this only when you manually downshift, or does it happen on kickdown?
Normal! driving when you come up to a stop sign 3rd.....clunk 2nd 1st the rpm increase "a bit" and then seems like the (torque converter did not unlock)
but nice idle 700 rpm................. upshift through the gears throttle controlled and up into the torque kicking in 45+ mph just like my other truck 2003/ 5.3 4L60E
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53 TuTone Extended Cab 350 4-Spd 3:08 (SOLD)
53 Chevy Moldy pearl green ZZ-4 4L60E 9" 3:25
55 GMC 1st Black Mll (ZZ4) ZZ6 TKO 600 5 sp 3:73
62 Solidaxle Corvette Roman Red (327
340hp 4spd 3:36) C4 & C5 suspension tube chassis
LS 3 4L70E
65 Corvette Coupe 327 350hp 4spd 4:11
78 Black Silverado SWB (350/350) 5.3 & 4L60E 3:42
2000 S-Type 3.0 (wife cruiser)
2003 GMC SCSB 5.3 4L60E 3:42
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Old 11-14-2015, 11:14 PM   #9
solidaxel
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Re: 2003 5.3 4L60E Down shifting

Quote:
Originally Posted by boostedc10 View Post
The EPC is in the transmission but you can read it on pins c (high) and d (low) of the transmission plug.
Thanks, I will have to wait on the empty rack to check that
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53 TuTone Extended Cab 350 4-Spd 3:08 (SOLD)
53 Chevy Moldy pearl green ZZ-4 4L60E 9" 3:25
55 GMC 1st Black Mll (ZZ4) ZZ6 TKO 600 5 sp 3:73
62 Solidaxle Corvette Roman Red (327
340hp 4spd 3:36) C4 & C5 suspension tube chassis
LS 3 4L70E
65 Corvette Coupe 327 350hp 4spd 4:11
78 Black Silverado SWB (350/350) 5.3 & 4L60E 3:42
2000 S-Type 3.0 (wife cruiser)
2003 GMC SCSB 5.3 4L60E 3:42
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Old 11-15-2015, 12:12 AM   #10
clinebarger
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Re: 2003 5.3 4L60E Down shifting

Do you have the TCC Brake wire hooked up/wired correctly?
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Old 11-15-2015, 12:36 AM   #11
solidaxel
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Re: 2003 5.3 4L60E Down shifting

Quote:
Originally Posted by clinebarger View Post
Do you have the TCC Brake wire hooked up/wired correctly?
Power to TCC until the brake is pushed
I will re check the cruise control wiring also
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53 TuTone Extended Cab 350 4-Spd 3:08 (SOLD)
53 Chevy Moldy pearl green ZZ-4 4L60E 9" 3:25
55 GMC 1st Black Mll (ZZ4) ZZ6 TKO 600 5 sp 3:73
62 Solidaxle Corvette Roman Red (327
340hp 4spd 3:36) C4 & C5 suspension tube chassis
LS 3 4L70E
65 Corvette Coupe 327 350hp 4spd 4:11
78 Black Silverado SWB (350/350) 5.3 & 4L60E 3:42
2000 S-Type 3.0 (wife cruiser)
2003 GMC SCSB 5.3 4L60E 3:42
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Old 11-15-2015, 12:39 AM   #12
solidaxel
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Re: 2003 5.3 4L60E Down shifting

The tail lights are LED, if that makes any difference
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53 TuTone Extended Cab 350 4-Spd 3:08 (SOLD)
53 Chevy Moldy pearl green ZZ-4 4L60E 9" 3:25
55 GMC 1st Black Mll (ZZ4) ZZ6 TKO 600 5 sp 3:73
62 Solidaxle Corvette Roman Red (327
340hp 4spd 3:36) C4 & C5 suspension tube chassis
LS 3 4L70E
65 Corvette Coupe 327 350hp 4spd 4:11
78 Black Silverado SWB (350/350) 5.3 & 4L60E 3:42
2000 S-Type 3.0 (wife cruiser)
2003 GMC SCSB 5.3 4L60E 3:42
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