2003 5.3 4L60E Down shifting - The 1947 - Present Chevrolet & GMC Truck Message Board Network

solidaxel · 11-13-2015, 06:21 PM

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???

boostedc10 · 11-13-2015, 06:54 PM

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.

solidaxel · 11-13-2015, 07:00 PM

Quote:

Originally Posted by boostedc10

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

clinebarger · 11-13-2015, 11:22 PM

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.

solidaxel · 11-14-2015, 05:07 PM

Yes we did switch computers first thing..........no change
O K, I am not sure where the EPC is located?

boostedc10 · 11-14-2015, 06:07 PM

The EPC is in the transmission but you can read it on pins c (high) and d (low) of the transmission plug.

BR3W CITY · 11-14-2015, 07:09 PM

Is this only when you manually downshift, or does it happen on kickdown?

solidaxel · 11-14-2015, 11:13 PM

Quote:

Originally Posted by BR3W CITY

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

solidaxel · 11-14-2015, 11:14 PM

Quote:

Originally Posted by boostedc10

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

clinebarger · 11-15-2015, 12:12 AM

Do you have the TCC Brake wire hooked up/wired correctly?

solidaxel · 11-15-2015, 12:36 AM

Quote:

Originally Posted by clinebarger

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

solidaxel · 11-15-2015, 12:39 AM

The tail lights are LED, if that makes any difference

11-13-2015, 06:21 PM	#1
solidaxel Registered User Join Date: Dec 2002 Location: Cactus Patch So. Az Posts: 4,749	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??? __________________ 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

11-13-2015, 06:54 PM	#2
boostedc10 Registered User Join Date: Oct 2012 Location: Detroit Posts: 748	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. __________________ Brandon Instagram: DRVFSTR Current Project: Beatrix - 1967 SWB LQ4/78mm Turbo/4L80e/ on bags Build thread: http://67-72chevytrucks.com/vboard/s...d.php?t=634691

11-13-2015, 11:22 PM	#4
clinebarger Senior Member Join Date: May 2009 Location: Fort Worth, TX Posts: 6,370	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.

11-14-2015, 05:07 PM	#5
solidaxel Registered User Join Date: Dec 2002 Location: Cactus Patch So. Az Posts: 4,749	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? __________________ 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

11-14-2015, 06:07 PM	#6
boostedc10 Registered User Join Date: Oct 2012 Location: Detroit Posts: 748	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.

11-14-2015, 07:09 PM	#7
BR3W CITY meowMEOWmeowMEOW Join Date: Sep 2009 Location: MKE WI Posts: 7,128	Re: 2003 5.3 4L60E Down shifting Is this only when you manually downshift, or does it happen on kickdown? __________________ *'66 Short Step / SD Tuned / Big Cam LQ4 / Backhalfed /Built 4l80e / #REBUILDEVERYTHING* MY BUILD THE H8RDCPTR //\\ MY YOUTUBE CHANNEL REV J HD

11-15-2015, 12:12 AM	#10
clinebarger Senior Member Join Date: May 2009 Location: Fort Worth, TX Posts: 6,370	Re: 2003 5.3 4L60E Down shifting Do you have the TCC Brake wire hooked up/wired correctly?

11-15-2015, 12:39 AM	#12
solidaxel Registered User Join Date: Dec 2002 Location: Cactus Patch So. Az Posts: 4,749	Re: 2003 5.3 4L60E Down shifting The tail lights are LED, if that makes any difference __________________ 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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