2003 Silverado Modified

[Cipher]

I recently swap out my 4.3l Vortec to a LS III, 6.0. However, I left the old 4l60E in it since it was pretty much brand new. I did the pinout for the 4l80E harness to the 4l60E that I found here:

. However, I have encountered a few issues that I will share.

1. Swapped the flywheel from the 4.3 to a 5.3 to match up
2. Had to remove the spacer from the flex plate to align the starter to the flywheel.
3. Reflashed ECM to accommodate the 6 cyl to 8 cyl swap along with Stage 1 CAM and cold air intake.
4. Removed the CATS
5. Installed long tube headers.
6. After the swap I had to replace the shifter cable to the 131" (only used the rear cable portion) but

Problem: After the swap the torque converter seems to lock up only after the fluid builds pressure. Looking for suggestions on the problem since I am not good with transmissions.

 

[shady]

Not sure what you mean by build pressure. But the converter won't lock up until your trans fluid reaches 85* in a normal 4l80e truck.
Maybe that's what's going on...

 

[Blue85]

Scan it to see if lockup is being commanded. A better scanner will let you command lockup to see what that does. You can also see what the pressure is and if there's any faults affecting it. If you didn't have fluid pressure it would be in neutral no matter which gear you select.

 

[Cipher]

Here's what it's doing. I jump in, start it, throw it in gear, and then have to wait a few seconds before I feel the tranny catch. If I Rev it, it will move but like it's slipping and not transferring all of the power.

 

[Blue85]

So we're not talking about the torque converter clutch then. That's only used to stop the slip at high speed cruising.

First thing, make sure you have the right dipstick for the application and set the level while running.

 

[Cipher]

Ok. Have enough fluid in it but still no joy. Latest issue is that sometime I have a hard time removing the key

 

[Blue85]

Can you borrow a transmission pressure gauge?

This is the dipstick tube and dipstick original to the transmission, with the same mounting?

Talk to us about wiring and which year transmission you segment swapped to. The connector and wiring changed at some point, which could mean the pressure solenoid is not being commanded correctly. For sure don't drive around if it's slipping.

 

[Cipher]

Need to ask mechanic about stick and tube. The tranny is brand new from 2022. 4l60e for a 2003 Silverado. The pinout was taken from here:

 

[Blue85]

What scanner are you using?

 

[ZooMad75]

Here's what it's doing. I jump in, start it, throw it in gear, and then have to wait a few seconds before I feel the tranny catch. If I Rev it, it will move but like it's slipping and not transferring all of the power.

Does this do that every time you start the truck or only after letting it sit for a longer amount of time? Like a few hours or overnight. I’ve seen some have a drain back issue when it sits overnight where enough fluid drains out of the converter and you fire the engine up and jam it into a gear right away it won’t move. Revving the engine up (spinning the pump faster) will fill the converter and allow it to drive.

Have you tried to just let the engine idle after it first start for a minute or so before putting the trans into gear?

Was the trans doing this with the previous 4.3?

I’m not real strong on the inner workings of a 4L60, but there can be some minor differences between the version for a 4.3 and any V8 SBC or LS. The converter would be one that for sure isn’t the same on a 4.3 as on a 5.3 much less a 6.0 with or without a aftermarket cam.

If the trans wasn’t doing this before I bet it’s something to do with that difference in the torque converter for a 4.3 truck.

Ok. Have enough fluid in it but still no joy. Latest issue is that sometime I have a hard time removing the key

That’s pretty common to those trucks. It’s mostly because the key and tumblers in the lock are worn down. I’ve had decent luck having a fresh key cut by the key code at a dealer. Trace cutting a key won’t help as it’s just tracing a worn key.

If the key is super worn the tumblers might be just as bad and a fresh key won’t fix it. At that point it’s time to get a new ignition lock cylinder. Aftermarket lock cylinders come with keys already coded to it. Your door locks won’t match if that matters. A dealer can sell you a uncoded lock and code it to match your existing key code.

 

[Cipher]

What scanner are you using?

Checked Wiring and it looks good. Had some oil in the connector so cleaned it out. Code reader had 3 codes. 740, 758, and 1860.