4l80e swap help

[05chevy]

i just did i 4l80e swap on my brother 99 1500.
He purchased a conversion harness off of the internet. Came with the adapter and new pig tail and pins to install the second speed sensor. we also installed a 243c transfer case that bolted right up to the 4l80e. almost every sensor on the transfer case is different except for the 6 pin plug on the motor. this transfer case only has 1 speed sensor also.

My main issue is that the truck feels like its in high gear. Hardly moves forward. I copied the transmission files from a 12212156 o.s. Truck still did the same thing. Hardly moves forward. I also recieved a P0740 and P0785. I think I have read that i have to shut those codes off to make this transmission function? Is this true? Here is the stock 4l60E tune from his truck. 17996

Any help with be appricatied. thank you

[05chevy]

Any help?

[joecar]

When it's in gear (Drive) what does the pid GM.GEAR show...?

What DTC's do you get...?

[joecar]

Disable P0785 and P0740 (in the Engine Diagnostics and the Transmission Diagnostics segments) and see what happens.

[05chevy]

D3. And will go from unknown to D3 when changing gears on the column.

I hooked a modis to it and can control all the solenoids. In the trans. It's almost like something is holding the truck back

[joecar]

Set D0961 and D0962 to 100% in all cells.

[joecar]

I don't think this matters, but set the correct ratios in D1201-5.

Also:
- set D0925-7 to be below D0910-2,
- set D0930-2 to be below D0915-7.

[joecar]

D3. And will go from unknown to D3 when changing gears on the column.

I hooked a modis to it and can control all the solenoids. In the trans. It's almost like something is holding the truck back
That's the wrong pid (GM.PRND)...

look at the pid GM.GEAR, it shows the actual gear being commanded by the PCM (i.e. it shows one of: 1st, 2nd, 3rd, 4th).

Also, check the manual gear switch on the side of the case, make sure the switch and/or harness are ok.

[5.7ute]

Was the trans segment you swapped in for a 4l80e?

[05chevy]

I copied and pasted from the 12212156 O.S. I got off of holdencrazy.com. into the stock tune off of the truck

[joecar]

But was it for a 4L80E...?

( I have a link to one somewhere here )

[05chevy]

Yes 2002 6.0l with 4l80e

[Taz]

... purchased a conversion harness off of the internet. Came with the adapter and new pig tail and pins to install the second speed sensor ...

Was it intended for use with a 4L80 tune ? Or did it include a relay (intended for use with a 4L60 tune) ?


... I copied the transmission files from a 12212156 o.s. ...

Simply copying the parameters from a 4L80 tune into a 4L60 tune won't make the tune compatible with a 4L80 ... the solenoid logic and TCC function are different. This requires an actual 4L80 tune, or a transmission segment swap into your current tune.

[05chevy]

Was it intended for use with a 4L80 tune ? Or did it include a relay (intended for use with a 4L60 tune) ?



Simply copying the parameters from a 4L80 tune into a 4L60 tune won't make the tune compatible with a 4L80 ... the solenoid logic and TCC function are different. This requires an actual 4L80 tune, or a transmission segment swap into your current tune.

The harness came with only the adapter plug and new vss wire to pin into the pcm.

How do I do a segment swap. Upgrade the 5.3/4l60e O.S. with a 6.0/4l80e O.S.?

[05chevy]

I also have the pcm from the 02 truck that this trans came out of. Could I just switch the pcm and vin number in the truck?

[05chevy]

I'm to the point now. I will pay someone to do the segment swap for me because I have to get my brothers truck back up and running. His other truck broke also. So he has nothing to drive.

[joecar]

When you do the segment swap you also have to repin a few wires... you need to check how the harness is pinned.

[05chevy]

When you do the segment swap you also have to repin a few wires... you need to check how the harness is pinned.

Even with a conversion harness?

[Taz]

These are some of the difficulties that can be encountered when people fail to do sufficient research and planning prior to going ahead with conversion projects.

By your description, it would appear that the adapter harness you purchased was intended for use with a 4L80 calibration.

You attached your original tune in post #1 of this thread.

Attached below is this same tune, but with 4L80 segments inserted.

Hopefully this will get you (and your brother) going again.

[05chevy]

I tried everything that you all suggested and had no luck. I have not tried your tune Taz. I ended up swapping in a pcm out of a 6.0/4l80e truck. And it shifts perfect. I know I said the truck is a 99 but I'm wondering if it has a 98 pcm. What I have read was the 98s are not compatible with a 4l80e. And I would have had more time to research this project but the pump went out of his dodge so we tried to get his chevy back up and running.

Thanks for all the help

Taz I will put the other pcm out and see if your tune works. And report back. Once again thank you

[Taz]

Glad to hear you got it going ... using the 2002 LQ4 / 4L80 PCM tells you that the wiring (adapter harness) is correct for use with a 4L80 tune. Other than some DTCs for the Alternator, Oxygen Sensors, and perhaps the EGR and Air Pump - that tune should work OK for now in your 1999 truck. The Injector Flow Rate is different, so the Fuel Trims may eventually cause DTCs.

The original PCM must have been a 1999, if you were able to install the 2002 PCM - the 1998 truck PCMs had 4 connectors (not 2 like your truck).

[MikeOD]

You can't segment swap a 2002 trans segment into a 99 OS...that's probably why it didn't work...it probably didn't copy anything to begin with. You can only segment swap (most of the time) when you have the same base OS.

There have been some occasional post production OS replacements from GM to solve TSB issues, and in some of those instances, while the OS changed, some segments did not...and in those cases, all of the segments can be used with either OS...but that's very rare.