fieroguru

iTrader: (1)

I have come to the conclusion (or fear) that for DoD to work with my LS4/F40 6 speed manual swap, I need to keep the TCM happy and trick into thinking it is still on a 4T65e-hd.

The reason I need to do this is several DoD enablers happen in the TCM and only the GMLAN Serial Data Bus communicates it between the TCM and the ECM.

Now as I try to get the system to work with a manual transmission, these are the 4 enabler functions that are my biggest concerns.

9. Transmission gear incorrect
10. Transmission range incorrect
11. Transmission gear shift in progress
*** Vehicle Speed Sensor

My concern about the VSS is that the two VSS wires go to the VSS and only a single VSS wire goes from the TCM to ECM (stock E67 LS4 calibration). Many other swaps using the E67 in a manual configuration were able to run both VSS wires directly to the ECM and get the Speedo to work, but the vehicle speed within the ECM (from a scanner) wouldn't show vehicle speed. The concern is if the ECM doesn't show the vehicle speed, will it enable DoD, or is it even looking for the VSS approval from the ECM, or does it come from the TCM through the High Speed GMLAN Serial Data Bus...

Probably the safest bet it to plan on installing the TCM in the center console area...

The electrical circuit side is one of my weaknesses... so as I look at what I can do to fool the TCM into thinking the 4T65e-hd is still present and working, I am taking a rather simplistic approach... and likely doing some things wrong. Any TCM circuit experts feel free to provide other suggestions.

The major unknown right now is how much of the TCM functions have to be correct in order for the TCM to give the ECM the go ahead for DoD activation. So at this point I am planning to error on the side of doing too much (I can always remove them later) vs. not doing enough and having to revisit the issue. The chart below has the majority of my thoughts/plans, but a high level plan of action:

1: Hard wire the inputs from the Range Selections so the TCM see's the transmission in DRIVE
2: All solenoid circuits wired up with fiero side marker light bulbs so they will see a load.
3: Wire up the fluid Temp with a resistor so the TCM thinks the transmission is at about 175 degrees
4: Connect all the normal wires between the TCM/ECM and external inputs as normal

Once those are done, I am down to two issues.
The VSS could be connected from the F40 to the TCM.... But then the TCM will see the 60Kppm vs 24K... Might just add a 30 tooth reluctor on the tripod housing or intermediate shaft (unless I can just progam the TCM to look for the 60K ppm input).
The ISS... only way to mimic this signal is to add a reluctor to the transmission input shaft... which won't be easy. I could added it to the engine crankshaft (possibly mill the OD of the flywheel or bolt it on the balancer), but not sure if the TCM will go nuts with the ISS seeing speed while the VSS is stationary (when stopped and the clutch in). The only time the 4T65e-hd sees this in Park/Neutral, but the TCM will not see the transmission in Park/Neutral).

Here is the updated TCM wiring details:


Any thoughts/guidance from the TCM tuner experts?

91parkave

iTrader: (4)

Have u thought about just using a silverado e67 with the 5.3 dod with a manual? Do u really need the dod and assosiated issues?

fieroguru

iTrader: (1)

To my knowledge, GM has never offered any vehicle with DoD/AFM and a manual transmission. It most likely is due to the harshness when going from 8 cly to 4cyl and back. In the autos they can make this transition smooth by unlocking the TCC, but you can't do that with a manual.

There are very few "needs" in life. I want DoD with a manual transmission (only between 55 and 80 mph) for fuel efficiency purposes. I think with the Fieros 2900 lb weight, the low internal losses from the F40 (vs. the 4T65e-hd), and DoD I could see 32 to 35 mpg on the highway.

Plus I like R&D and this has been a fun challange to get figured out.

fieroguru

iTrader: (1)

Anyone know if you can change the reluctor wheel size for the Input Shaft Speed (ISS) sensor in the TCM programming?

It looks like the stock ISS reluctor is 25 teeth and the output shaft gear on the F40 is 22. I am wanting to know if I could change the program to accept the 22 tooth input for the Input Shaft Speed Sensor.

DaytonaTA

iTrader: (6)

Looks like this thread died about 8 years ago, but I’ve been trying to solve the same problem. Did you ever figure it out?

fieroguru

iTrader: (1)

The swap fired up in 2/10/2013 and ran largely issue free for 6.5 years and 55K miles. In Sept 2019 had a DoD lifter collapse, so I took the engine down for more upgrades.

With the resistors, I was able to make the TCM think it was still connected to the auto. When I would scan, you could see the TCM doing gear changes. There were a couple of DTC for the auto that HP tuners could not turn off, but a friend with Tuner Cat was able to turn them off.

With my current round up upgrades, I have given up on DoD (finally removed it) and switching to a manual transmission OS. Starting with a manual transmission OS is what I recommend these days.