6l80e with tap shift no BCM

[gbg]

I looked over your tune file and couldn't find any issues. I did notice that both gbg and DHC OS's vary from mine though. Mine for the T43, GM A6 is 24265260.

I don't like to flash entire OS as I've seen too many horror stories on this forum about bricking ECM/TCM's, but it could be that your OS does not support hardwire TUTD. I can't confirm nor deny that this is true, but have heard a lot of people claim this is case. Before flashing a new OS that has been confirmed that TUTD works, I would try a few things.

Change these settings:
Up/Down Req: Disabled
Range Select: Enabled
Range Active: D6

Then write the calibration, with the engine off, key on, shift into drive. It should immediately indicate TUTD for shift mode in VCM Scanner (just looked at this and in v 4.0.6, it is showing "unknown: 14200" instead of "Trans Shift Mode").
If this doesn't work, I would write Entire.
I tested this on my vehicle and it immediately goes into TUTD mode when D6 is selected. See the attached log.

If none of this works, I would write another OS. Mine is attached, but you will need to figure out if these are compatible. Please do your research before killing something.

This is what I tried last night with no success, it just stays in normal shift mode. Thanks for the log! It is nice to see what I should be looking for to confirm that it is not working right.

For writing a new OS I have never done that and do not want to brick anything. I have seen two tunes now that are working with TUTD and they both have the 24265260 OS however I am running the 24261871 and do not know if I can make the switch safely.

Thanks for all the help!

[gbg]

I did eventually get mine to work. Because the Lokar shifter would not allow for a detent change I had to get creative with the TUTD shift schedule for this particular project. I had another project up after that one that I used a corvette shifter in, which allowed the detent change and everything worked awesome. Down side to the Lokar shifter was no detent change so I had to keep the TUTD fairly tame in the shift schedule, now the corvette shifter allowed me to get nasty with the TUTD schedule. Attached are both tunes for each.
The tune named final was for Lokar shifter without detent change and the Maf1_spark1_trans1 is for the corvette shifter. It took a while trying things to make the Lokar work.

Hope this helps a little

Interesting, this tune uses the same T43 OS as I am running!

[gbg]

to clarify the Maf1_spark1_trans1 tune you posted has the same T43 OS 24261871 that I have in mine and you are saying this one worked fine?

[DHC]

gbg,
the tune attached in this post was the final one I wrote for this vehicle. This was using a corvette shifter which allowed detent change to D5 and worked like a champ. Be careful very aggressive on TUTD. Make sure in the scanner you watch the PRNDL for status change and shift mode will say TUTD once a TU or TD command has been performed, takes a change on the resistance ladder to initiate the shift mode to change. attached is a log showing the change. PRNDL change at time right after 4min 21 sec into log and then the mode changes at 4min 23sec.

let me know if this works for you.

[gbg]

gbg,
the tune attached in this post was the final one I wrote for this vehicle. This was using a corvette shifter which allowed detent change to D5 and worked like a champ. Be careful very aggressive on TUTD. Make sure in the scanner you watch the PRNDL for status change and shift mode will say TUTD once a TU or TD command has been performed, takes a change on the resistance ladder to initiate the shift mode to change. attached is a log showing the change. PRNDL change at time right after 4min 21 sec into log and then the mode changes at 4min 23sec.

let me know if this works for you.

The comparison file shows a LOT of differences, any guidance on what areas to focus on to copy over?

[DHC]

gbg,
For shits and giggles, try copying over everything transmission related as it is in my tune. Make sure that you don't change speedometer related stuff, also make sure the MPH in the scanner is within 1 mph of GPS speed. Use the comparison log, ctrl+5, and then copy all trans only parameters over and test. This trans tune is changed a lot for shift feel and schedule. It is in a series 80 land cruiser with offroad in mind for TUTD.

[gbg]

gbg,
For shits and giggles, try copying over everything transmission related as it is in my tune. Make sure that you don't change speedometer related stuff, also make sure the MPH in the scanner is within 1 mph of GPS speed. Use the comparison log, ctrl+5, and then copy all trans only parameters over and test. This trans tune is changed a lot for shift feel and schedule. It is in a series 80 land cruiser with offroad in mind for TUTD.

This one is a land cruiser too! A custom stretched Fj40 made into a 4 door on 42 inch tires. So it may actually be appropriate for my needs. I just don’t want to hurt reliability of the trans.

[DHC]

Ive got several of these trans is heavy 4x4 stuff with big tires and haven't had an issue with life, so far knock on wood. I leave torque management alone and get the crisp feel from the inertias, pressures and time of shifts for all my 6, 8 and 10x stuff. I do sometimes modify the minimum spark table in the ECM side, mostly on light fast revving stuff. The difference between most of my trans cals are shift schedule which I use bluecat to get me close and tweak specific needs from there. Make sure to have enough trans cooler. Derale 13870 is our go to cooler.

[gt1guy]

Keep this going guys. This is good stuff.

I'm building a 4dr Jeep JK with a LS3 crate/6l90. Stand alone LS harness and all the Jeep wiring replaced with a Painless kit. I have a Winters shifter that hits all 7 detents in the trans (PRN4321), also have a Twist Machine paddle setup for TUTD duties.

Just trying to absorb all the information I can before I get close to firing up my rig.

[gbg]

Well I copied everything from the trans section over using the compare logs and it still isn’t working :/

[gbg]

Just for due diligence I want to check resistance again, can someone confirm what I should see at the trans connector pin?

[87skier]

Just for due diligence I want to check resistance again, can someone confirm what I should see at the trans connector pin?

Well, you will get 12 V at the pin with the ignition on. Your switch should be 12 V hot with the key on and since the wire is open you will get 12 V. To check the wire, you will need another resistor between 1k and 10k.

First measure open circuit voltage at the harness (V_oc), then use your meter to measure your resistor (R_gnd). Now, connect the meter directly to the pin in the transmission harness. Also connect the transmission to the resistor then to battery negative. Set the multimeter to volts.

You should measure:
Switch neutral: V_oc*R_gnd/(R_gnd + 8.85k)
Switch down: V_oc*R_gnd/(R_gnd + 1.27k)
Switch up: V_oc*R_gnd/(R_gnd + 2.878k)

Which if you have 12V at pin and a 1K resistance to ground
Switch neutral: 1.30 volts
Switch down: 5.29 volts
Switch up: 3.09 volts

[gbg]

My resistances are

Neutral (8.25k)
Down (1.27k)
Up (2.87k)


Your chart says neutrL should be 8.85k?

For the voltage test I am not understanding the use of the 1k resistor or how to test with the meter. Wouldn’t you just connect the meter to the transmission pin and the other end of the meter to ground? Maybe I am missing something obvious .

Thanks!

[jpndave]

The 8.25 should be correct. I would go from the "Reference Ground" not a chassis ground just in case. Here is a close up of the OEM resistance diagram.

6L80E TUTD.png

[jpndave]

And the whole diagram. This is 08 Corvette.
08 Corvette Engine TCM Conns to do tap shifting.pdf

[jpndave]

I have an L20 (4.8L with VVT) with e38 and 6L90E with T43 controller and using veee8's info it works exactly as it should. This engine was out of a van if anyone is curious.


If anyone is looking to make their own harness you'll need:

6L80/90 connector: Mouser
Cable seal: EFI Connection

8.25k ohm 1% tolerance resistor: Digi-key
4.42k ohm 1% tolerance resistor: Digi-key
1.5k ohm 1% tolerance resistor: Digi-key

You'll also need either two switches or a momentary on-off-on switch. I recommend the second so that up and down can't be requested at the same time. I know this is from 3 different places, but all the part numbers are here. The kostal connectors for the transmission are hard to find.

Here is the info earlier in the thread starting at post 31. 87skier did a good job on clarifying this.

Remember if you are measuring these in parallel it adds up like this 1 / R = 1 / R1 + 1 / R2 or 8.25K manual "on", 2.87K "up" and 1.09K "down" if my math is right through the complete combined circuit. So in the factory drawing close-up above from #3 at the top to #5 at the bottom. If you measure voltage, it would be based on your starting voltage and apply the appropriate resistance. I don't have the shifter in hand to check with my meter but that should be correct.

[87skier]

My resistances are

Neutral (8.25k)
Down (1.27k)
Up (2.87k)


Your chart says neutrL should be 8.85k?

For the voltage test I am not understanding the use of the 1k resistor or how to test with the meter. Wouldn?t you just connect the meter to the transmission pin and the other end of the meter to ground? Maybe I am missing something obvious .

Thanks!

8.25k is correct.

This test is for if you have the switch wired in and only want to check at the transmission. The other wire on your switch should be connected to 12v, switched power.
In this case, if you were to connect the meter to the pin at the transmission, and the other end to ground, you will measuring a bunch of combined resistances of all the stuff in your vehicle and the battery.

If you have easy access to the switch wiring, just check the resistance. If you don't, you will need to do what I posted earlier, or what follows.

The additional resistor is used since you need to measure voltage. Connecting the meter to the pin and ground without providing a separate path you will only get open circuit voltage instead of actual readings, this is why you need the resistor. If you don't have one, you can measure current.
It is possible to do all of this in current measurement, which would require connecting the meter from the pin to ground.

If you have 12v at the switch, then:
Neutral: 1.36 mA = 12v/8.25k
Up: 4.18 mA
Down: 9.45 mA

[gbg]

8.25k is correct.

This test is for if you have the switch wired in and only want to check at the transmission. The other wire on your switch should be connected to 12v, switched power.
In this case, if you were to connect the meter to the pin at the transmission, and the other end to ground, you will measuring a bunch of combined resistances of all the stuff in your vehicle and the battery.

If you have easy access to the switch wiring, just check the resistance. If you don't, you will need to do what I posted earlier, or what follows.

The additional resistor is used since you need to measure voltage. Connecting the meter to the pin and ground without providing a separate path you will only get open circuit voltage instead of actual readings, this is why you need the resistor. If you don't have one, you can measure current.
It is possible to do all of this in current measurement, which would require connecting the meter from the pin to ground.

If you have 12v at the switch, then:
Neutral: 1.36 mA = 12v/8.25k
Up: 4.18 mA
Down: 9.45 mA

So I checked the resistance values at the pin, I did not check the voltage or current. I am not really clear on how to verify that my wiring is functioning correctly. The voltage values of course vary depending on engine running or not.

I loaded a known working program running the same OS as my T43 and it still did not work. The shift mode never changes from normal in the scanner, this is why I am trying to double check the circuit. What else could be keeping this from working?

I appreciate all the detailed feedback you all have given,
Thanks!

[ntilley52]

87Skier here is my file, it took me a bit cuz my laptop crapped out. Had to get a new one. Please have a look. thanks

[ntilley52]

Success! i got it working, just some settings in the NORMAL TUTD SPEED charts. Works like i want now. Thanks for the help guys, especially 87skier. I guess i just need more hands on time with the software to learn the order of operations