The 1947 - Present Chevrolet & GMC Truck Message Board Network

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- LSx Swaps (https://67-72chevytrucks.com/vboard/forumdisplay.php?f=206)

- - 4.8L/6L90E swap??? (https://67-72chevytrucks.com/vboard/showthread.php?t=732532)

Re: 4.8L/6L90E swap???

Ok.
If I don’t have the blue/white strip wire connected to anything I get a yes on the status. I connected the blue/white strip wire to my relay with no resister and it reads no. I touch brake and I get a yes. This is without the truck running just key on. When I start the truck the status reads NO when unplugged and stays a NO no matter what.
Always a NO. When running.
I shut truck off and it goes back to working YES pedal depressed and NO pedal released.

Not sure what to try.

Re: 4.8L/6L90E swap???

Hey 87skier,
I followed the attached and had no luck. When I dropped into the M position which is just below the normal drive. Is that D4? If you follow the list in the range drop down it’s
1,p,r,n,d6,d5,d4,d3,d2,d1.

I have a Dakota digital dash and when I drop into M it’s just reads “second” and the trans shifts like I was in drive and the TUTD switch does not work.
Any ideas?

Quote:

Originally Posted by 87Skier (Post 8157668)

It took longer than I expected to get around to this. If anyone is curious about the TUTD for the 6L80/90 you don't have to do a lot to get it working if you are doing a swap. Here's what you'll need to do:

1. Run a new wire

Parts:
Wire (18-20 awg)
Weatherpack/Metripack crimper: Amazon
6L80/90 connector: Mouser
Cable seal: EFI Connection

GM didn't hardwire the TUTD. You'll need to add a connector and wire to the transmission harness. See this document from Speartech: Speartech

2. Use a prebuilt switch, like this one: Speartech

OR save yourself about $130 and do it yourself

Parts:
8.25k ohm 1% tolerance resistor: Digi-key
4.42k ohm 1% tolerance resistor: Digi-key
1.5k ohm 1% tolerance resistor: Digi-key
Momentary rocker switch (anything will do here): Digi-key

Wire it up according to the attached schematic. I'll let you decide if you want it all inline and clean or if you want to hot glue the components into the small box or something, but solder everything.

3. Retune your transmission:
You need to tell your computer you are running a 'Hardwire' TUTD, and setup the forced shift speeds. I used HPTuners. Also, these numbers are for a tall geared vehicle, setup your speeds for your vehicle. See the hptuners pictures.

I set mine to engage TUTD when the gear select is D4 (second position for my transmission), and a button press is detected.

Re: 4.8L/6L90E swap???

Open up VCM scanner and log "PRNDL status" and "Trans Shift Mode".

Shift into gear you want TUTD to work, and look at PRNDL status. Mine says D4 for example. Yours might be D5, D3, etc...

Whatever it says, make sure Trans > Auto Shift Properties > General > TUTD > Range Active, shows exactly the same.

Also make sure your settings match the ones in the pictures. Let me know if everything matches.

Re: 4.8L/6L90E swap???

Hey 87skier. My truck is d5.
Do I adjust the tap up/tap down as mine doesn’t show force shifts.

Re: 4.8L/6L90E swap???

If it shows "D5" in the scanner then make sure it says D5 in VCM Editor.

Those tables are just the maximum's, so it will shift regardless of input. It may prevent the TUTD system from enabling if the tables are set incorrectly. For now you can set all the upshift speeds to 100, and all the downshift speeds to 0 to rule this out.

Re: 4.8L/6L90E swap???

First off I want the say thanks for the help.

I was able to use your numbers as a base line as for some reason my settings were at like 317. I checked yours against a 2012 Camero e38 ecm set up and they are almost exact.

I set them to your numbers and was able to get the tap up and tap down working. I do have to alter them as they want to auto shift earlier than I want. I am sure it’s rear gear and tire difference. But the TUTD works great.
I will be starting a thread about this TUTD set up. I would love for you to be part of it. Are you ok with me using your info?
Let me know or maybe you can just add to my thread.
Here is a teaser!!!

Re: 4.8L/6L90E swap???

I am glad you got it working.

Please use all the info you want, and I can add to the other if you want.

I like the shifter setup. I don't think I've seen anyone put a new style shifter in and use the buttons that way.